CGI.pm - a Perl5 CGI Library

Abstract

Everything is done through a ``CGI'' object. When you create one of these objects it examines the environment for a query string, parses it, and stores the results. You can then ask the CGI object to return or modify the query values. CGI objects handle POST and GET methods correctly, and correctly distinguish between scripts called from <ISINDEX> documents and form-based documents. In fact you can debug your script from the command line without worrying about setting up environment variables.

A script to create a fill-out form that remembers its state each time it's invoked is very easy to write with CGI.pm:

#!/usr/local/bin/perl

use CGI qw(:standard);

print header;
print start_html('A Simple Example'),
    h1('A Simple Example'),
    start_form,
    "What's your name? ",textfield('name'),
    p,
    "What's the combination?",
    p,
    checkbox_group(-name=>'words',
		   -values=>['eenie','meenie','minie','moe'],
		   -defaults=>['eenie','minie']),
    p,
    "What's your favorite color? ",
    popup_menu(-name=>'color',
	       -values=>['red','green','blue','chartreuse']),
    p,
    submit,
    end_form,
    hr;

if (param()) {
    print 
	"Your name is",em(param('name')),
	p,
	"The keywords are: ",em(join(", ",param('words'))),
	p,
	"Your favorite color is ",em(param('color')),
	hr;
}
print end_html;

Contents

Downloads

• Download gzip tar archive (Unix)
• Download pkzip archive (Windows)
• Download sit archive (Macintosh)
• Download just the CGI module (uncompressed)
• Archive of Old Versions

Installation

• Download gzip tar archive (Unix)
• Download pkzip archive (Windows)
• Download sit archive (Macintosh)
• Download just the CGI module (uncompressed)

The current version of the software can always be downloaded from the master copy of this document maintained at http://stein.cshl.org/WWW/software/CGI/.

This package requires perl 5.004 or higher. Earlier versions of Perl may work, but CGI.pm has not been tested with them. If you're really stuck, edit the source code to remove the line that says "require 5.004", but don't be surprised if you run into problems.

If you are using a Unix system, you should have perl do the installation for you. Move to the directory containing CGI.pm and type the following commands:

   % perl Makefile.PL
   % make
   % make install

This will create two new files in your Perl library. CGI.pm is the main library file. Carp.pm (in the subdirectory "CGI") contains some optional utility routines for writing nicely formatted error messages into your server logs. See the Carp.pm man page for more details.

If you get error messages when you try to install, then you are either:

1. Running a Windows NT or Macintosh port of Perl that doesn't have make or the MakeMaker program built into it.
2. Have an old version of Perl. Upgrade to 5.004 or higher.

  > cd CGI.pm-2.73
  > copy CGI.pm C:\Perl\lib
  > mkdir C:\Perl\lib\CGI
  > copy CGI\*.pm C:\Perl\lib\CGI

For Macintosh users, just drag the file named CGI.pm into the folder where your other Perl .pm files are stored. Also drag the subfolder named "CGI".

If you do not have sufficient privileges to install into /usr/local/lib/perl5, you can still use CGI.pm. Modify the installation recipe as follows:

   % perl Makefile.PL INSTALLDIRS=site INSTALLSITELIB=/home/your/private/dir
   % make
   % make install

use lib '/home/your/private/dir';
use CGI;

Notes on using CGI.pm in NT and other non-Unix platforms

Function-Oriented vs Object-Oriented Use

#!/usr/local/bin/perl
use CGI qw/:standard/;
print header(),
      start_html(-title=>'Wow!'),
      h1('Wow!'),
      'Look Ma, no hands!',
      end_html();

In addition to the standard set, there are many optional sets of less frequently used CGI functions. See Importing CGI Methods for full details.

In the object-oriented mode, you use CGI; without specifying any functions or function sets to import. In this case, you communicate with CGI.pm via a CGI object. The object is created by a call to CGI::new() and encapsulates all the state information about the current CGI transaction, such as values of the CGI parameters passed to your script. Although more verbose, this coding style has the advantage of allowing you to create multiple CGI objects, save their state to disk or to a database, and otherwise manipulate them to achieve neat effects.

The same script written using the object-oriented style looks like this:

#!/usr/local/bin/perl
use CGI;
$q = new CGI;
print $q->header(),
      $q->start_html(-title=>'Wow!'),
      $q->h1('Wow!'),
      'Look Ma, no hands!',
      $q->end_html();

Many of the code examples below show the object-oriented coding style. Mentally translate them into the function-oriented style if you prefer.

Creating a new CGI object

    use CGI;
    $query = new CGI;

An alternative form of the new() method allows you to read script parameters from a previously-opened file handle:

    $query = new CGI(FILEHANDLE)

open (IN,"test.in") || die;
while (!eof(IN)) {
    my $q = new CGI(IN);
    push(@queries,$q);
}

    my $q = new CGI(\*IN);

If you are using the function-oriented interface and want to initialize CGI state from a file handle, the way to do this is with restore_parameters(). This will (re)initialize the default CGI object from the indicated file handle.

open (IN,"test.in") || die;
restore_parameters(IN);
close IN;

You can initialize a CGI object from an associative-array reference. Values can be either single- or multivalued:

$query = new CGI({'dinosaur'=>'barney',
                  'song'=>'I love you',
                  'friends'=>[qw/Jessica George Nancy/]});

$query = new CGI('dinosaur=barney&color=purple');

$old_query = new CGI;
$new_query = new CGI($old_query);

This form also allows you to create a CGI object that is initially empty:

$empty_query = new CGI('');

If you are using mod_perl, you can initialize a CGI object at any stage of the request by passing the request object to CGI->new:

$q = CGI->new($r);

To do this with the function-oriented interface, set Apache->request($r) before calling the first CGI function.

Finally, you can pass code reference to new() in order to install an upload_hook function that will be called regularly while a long file is being uploaded. See Creating a File Upload Field for details.

See advanced techniques for more information.

Fetching A List Of Keywords From The Query

    @keywords = $query->keywords

Fetching The Names Of All The Parameters Passed To Your Script

    @names = $query->param 

Fetching The Value(s) Of A Named Parameter

   @values = $query->param('foo');
             -or-
   $value = $query->param('foo');

If a value is not given in the query string, as in the queries "name1=&name2=" or "name1&name2", it will be returned as an empty string (not undef). This feature is new in 2.63, and was introduced to avoid multiple "undefined value" warnings when running with the -w switch.

If the parameter does not exist at all, then param() will return undef in a scalar context, and the empty list in a list context.

Setting The Value(s) Of A Named Parameter

   $query->param('foo','an','array','of','values');
                   -or-
   $query->param(-name=>'foo',-values=>['an','array','of','values']);

The second example shows an alternative "named parameter" style of function call that is accepted by most of the CGI methods. See Calling CGI functions that Take Multiple Arguments for an explanation of this style.

Appending a Parameter

   $query->append(-name=>'foo',-values=>['yet','more','values']);

Deleting a Named Parameter Entirely

   $query->delete('foo');

Deleting all Parameters

   $query->delete_all();

Handling non-URLencoded Arguments

If POSTed data is not of type application/x-www-form-urlencoded or multipart/form-data, then the POSTed data will not be processed, but instead be returned as-is in a parameter named POSTDATA. To retrieve it, use code like this:

   my $data = $query->param('POSTDATA');

Importing parameters into a namespace

   $query->import_names('R');
   print "Your name is $R::name\n"
   print "Your favorite colors are @R::colors\n";

If you don't specify a name space, this method assumes namespace "Q".

An optional second argument to import_names, if present and non-zero, will delete the contents of the namespace before loading it. This may be useful for environments like mod_perl in which the script does not exit after processing a request.

Warning: do not import into namespace 'main'. This represents a major security risk, as evil people could then use this feature to redefine central variables such as @INC. CGI.pm will exit with an error if you try to do this.

NOTE: Variable names are transformed as necessary into legal Perl variable names. All non-legal characters are transformed into underscores. If you need to keep the original names, you should use the param() method instead to access CGI variables by name.

Direct Access to the Parameter List

$q->param_fetch('address')->[1] = '1313 Mockingbird Lane';
unshift @{$q->param_fetch(-name=>'address')},'George Munster';

You may call param_fetch() with the name of the CGI parameter, or with the -name argument, which has the same meaning as elsewhere.

Fetching the Parameter List as a Hash

$params = $q->Vars;
print $params->{'address'};
@foo = split("\0",$params->{'foo'});
%params = $q->Vars;

use CGI ':cgi-lib';
$params = Vars;

Many people want to fetch the entire parameter list as a hash in which the keys are the names of the CGI parameters, and the values are the parameters' values. The Vars() method does this. Called in a scalar context, it returns the parameter list as a tied hash reference. Changing a key changes the value of the parameter in the underlying CGI parameter list. Called in an list context, it returns the parameter list as an ordinary hash. This allows you to read the contents of the parameter list, but not to change it.

When using this, the thing you must watch out for are multivalued CGI parameters. Because a hash cannot distinguish between scalar and list context, multivalued parameters will be returned as a packed string, separated by the "\0" (null) character. You must split this packed string in order to get at the individual values. This is the convention introduced long ago by Steve Brenner in his cgi-lib.pl module for Perl version 4.

If you wish to use Vars() as a function, import the :cgi-lib set of function calls (also see the section on CGI-LIB compatibility).

RETRIEVING CGI ERRORS

Errors can occur while processing user input, particularly when processing uploaded files. When these errors occur, CGI will stop processing and return an empty parameter list. You can test for the existence and nature of errors using the cgi_error() function. The error messages are formatted as HTTP status codes. You can either incorporate the error text into an HTML page, or use it as the value of the HTTP status:

    my $error = $q->cgi_error;
    if ($error) {
	print $q->header(-status=>$error),
	      $q->start_html('Problems'),
              $q->h2('Request not processed'),
	      $q->strong($error);
        exit 0;
    }

When using the function-oriented interface (see the next section), errors may only occur the first time you call param(). Be prepared for this! Table of contents

Saving the Current State of a Form

Saving the State to a File

   $query->save(FILEHANDLE)

If you wish to use this method from the function-oriented (non-OO) interface, the exported name for this method is save_parameters(). See advanced techniques for more information.

Saving the State in a Self-Referencing URL

   $my_url=$query->self_url

If you'd like to get the URL without the entire query string appended to it, use the url() method:

   $my_self=$query->url

Obtaining the Script's URL

    $full_url      = $query->url();
    $full_url      = $query->url(-full=>1);  #alternative syntax
    $relative_url  = $query->url(-relative=>1);
    $absolute_url  = $query->url(-absolute=>1);
    $url_with_path = $query->url(-path_info=>1);
    $url_with_path_and_query = $query->url(-path_info=>1,-query=>1);

http://your.host.com/path/to/script.cgi

-absolute

If true, produce an absolute URL, e.g.

/path/to/script.cgi
      

-relative

Produce a relative URL. This is useful if you want to reinvoke your script with different parameters. For example:

    script.cgi

-full

Produce the full URL, exactly as if called without any arguments. This overrides the -relative and -absolute arguments.

-path,-path_info

Append the additional path information to the URL. This can be combined with -full, -absolute or -relative. -path_info is provided as a synonym.

-query (-query_string)

Append the query string to the URL. This can be combined with -full, -absolute or -relative. -query_string is provided as a synonym.

Mixing POST and URL Parameters

   $color = $query->url_param('color');

Under no circumstances will the contents of the URL query string interfere with similarly-named CGI parameters in POSTed forms. If you try to mix a URL query string with a form submitted with the GET method, the results will not be what you expect.

Table of contents

Calling CGI Functions that Take Multiple Arguments

   $field = $query->radio_group(-name=>'OS',
                                -values=>[Unix,Windows,Macintosh],
                                -default=>'Unix');

   $field = $query->textfield(-name=>'State',
                              -default=>'gaseous',
                              -justification=>'RIGHT');

   <INPUT TYPE="textfield" NAME="State" VALUE="gaseous"
          JUSTIFICATION="RIGHT">

HTML/HTTP parameters that contain internal hyphens, such as -Content-language can be passed by putting quotes around them, or by using an underscore for the second hyphen, e.g. -Content_language.

The fact that you must use curly {} braces around the attributes passed to functions that create simple HTML tags but don't use them around the arguments passed to all other functions has many people, including myself, confused. As of 2.37b7, the syntax is extended to allow you to use curly braces for all function calls:

   $field = $query->radio_group({-name=>'OS',
                                -values=>[Unix,Windows,Macintosh],
                                -default=>'Unix'});

Creating the HTTP Header

Creating the Standard Header for a Virtual Document

   print $query->header('image/gif');

An extended form of this method allows you to specify a status code and a message to pass back to the browser:

   print $query->header(-type=>'image/gif',
                        -status=>'204 No Response');

Several other named parameters are recognized. Here's a contrived example that uses them all:

   print $query->header(-type=>'image/gif',
                        -status=>'402 Payment Required',
                        -expires=>'+3d',
                        -cookie=>$my_cookie,
                        -charset=>'UTF-7',
                        -attachment=>'foo.gif',
                        -Cost=>'$0.02');

-expires

	+30s                              30 seconds from now
	+10m                              ten minutes from now
	+1h	                          one hour from now
        -1d                               yesterday (i.e. "ASAP!")
	now                               immediately
	+3M                               in three months
        +10y                              in ten years time
	Thu, 25-Apr-1999 00:40:33 GMT     at the indicated time & date

CGI::expires() is the static function call used internally that turns relative time intervals into HTTP dates. You can call it directly if you wish.

-cookie

-nph

print $query->header(-nph=>1,
                        -status=>'200 OK',
                        -type=>'text/html');

1. You are using Microsoft Internet Information Server.
2. If you need to create unbuffered output, for example for use in a "server push" script.
3. To take advantage of HTTP extensions not supported by your server.

-charset

-attachment

-p3p

print header(-p3p=>[qw(CAO DSP LAW CURa)]);
print header(-p3p=>'CAO DSP LAW CURa');

P3P: policyref="/w3c/p3p.xml" cp="CAO DSP LAW CURa"

Other header fields

   Cost: $0.02

Creating the Header for a Redirection Request

   print $query->redirect('http://somewhere.else/in/the/world');

You can add your own headers to this as in the header() method.

You should always use full URLs (including the http: or ftp: part) in redirection requests. Relative URLs will not work correctly.

An alternative syntax for redirect() is:

print $query->redirect(-location=>'http://somewhere.else/',
                          -nph=>1,
                          -status=>301);

The -nph parameter, if non-zero tells CGI.pm that this script is running as a no-parsed-header script. See Using NPH Scripts for more information.

The -status parameter will set the status of the redirect. HTTP defines three different possible redirection status codes:

301 Moved Permanently
302 Found
303 See Other

The default if not specified is 302, which means "moved temporarily." You may change the status to another status code if you wish. Be advised that changing the status to anything other than 301, 302 or 303 will probably break redirection.

The -method parameter tells the browser what method to use for redirection. This is handy if, for example, your script was called from a fill-out form POST operation, but you want to redirect the browser to a static page that requires a GET.

All other parameters recognized by the header() method are also valid in redirect. Table of contents

HTML Shortcuts

Creating an HTML Header

   named parameter style
   print $query->start_html(-title=>'Secrets of the Pyramids',
                            -author=>'fred@capricorn.org',
                            -base=>'true',
			    -meta=>{'keywords'=>'pharoah secret mummy',
                                    'copyright'=>'copyright 1996 King Tut'},
			    -style=>{'src'=>'/styles/style1.css'},
                            -dtd=>1,
                            -BGCOLOR=>'blue');

   old style
   print $query->start_html('Secrets of the Pyramids',
                            'fred@capricorn.org','true');

• The title (-title)
• The author's e-mail address (will create a <LINK REV="MADE"> tag if present (-author)
• A true flag if you want to include a <BASE> tag in the header (-base). This helps resolve relative addresses to absolute ones when the document is moved, but makes the document hierarchy non-portable. Use with care!
• A -xbase parameter, if you want to include a <BASE> tag that points to some external location. Example:

        print $query->start_html(-title=>'Secrets of the Pyramids',
                                 -xbase=>'http://www.nile.eg/pyramid.html');
        

• A -target parameter, if you want to have all links and fill out forms on the page go to a different frame. Example:

        print $query->start_html(-title=>'Secrets of the Pyramids',
                                 -target=>'answer_frame');
        

  -target can be used with either -xbase or -base.
• A -meta parameter to define one or more <META> tags. Pass this parameter a reference to an associative array containing key/value pairs. Each pair becomes a <META> tag in a format similar to this one.

        <META NAME="keywords" CONTENT="pharoah secret mummy">
        <META NAME="description" CONTENT="copyright 1996 King Tut">
        

  To create an HTTP-EQUIV tag, use the -head argument as described below.
• The -encoding argument can be used to specify the character set for XHTML. It defaults to iso-8859-1 if not specified.
• A -lang> argument is used to incorporate a language attribute into the <HTM>> tag. The default if not specified is "en-US" for US English. For example:

      print $q->start_html(-lang=>'fr-CA');
  

  To leave off the lang attribute, as you must do if you want to generate legal HTML 3.2 or earlier, pass the empty string (-lang=>'').
• A -dtd parameter to make start_html() generate an SGML document type definition for the document. This is used by SGML editors and high-end Web publishing systems to determine the type of the document. However, it breaks some browsers, in particular AOL's. The value of this parameter can be one of:
  1. A valid DTD (see http://ugweb.cs.ualberta.ca/%7egerald/validate/lib/catalog for a list). Example:

     -dtd=>'-//W3C//DTD HTML 3.2//EN'

  2. A true value that does not begin with "-//", in which case you will get the standard default DTD (valid for HTML 2.0).
  You can change the default DTD by calling default_dtd() with the preferred value.
• A -style parameter to define a cascading stylesheet. More information on this can be found in Limited Support for Cascading Style Sheets
• A -head parameter to define other arbitrary elements of the <HEAD> section. For example:

        print start_html(-head=>Link({-rel=>'next',
                         -href=>'http://www.capricorn.com/s2.html'}));
  
        

  or even

        print start_html(-head=>[ Link({-rel=>'next',
  			                 -href=>'http://www.capricorn.com/s2.html'}),
  			           Link({-rel=>'previous',
  				         -href=>'http://www.capricorn.com/s1.html'})
  			      ]
  		      );
        

  To create an HTTP-EQUIV tag, use something like this:

        print start_html(-head=>meta({-http_equiv=>'Content-Type',
                                         -content=>'text/html'}))
        

• A -script parameter to define Netscape JavaScript functions to incorporate into the HTML page. This is the preferred way to define a library of JavaScript functions that will be called from elsewhere within the page. CGI.pm will attempt to format the JavaScript code in such a way that non-Netscape browsers won't try to display the JavaScript code. Unfortunately some browsers get confused nevertheless. Here's an example of how to create a JavaScript library and incorporating it into the HTML code header:

        $query = new CGI;
        print $query->header;
        
        $JSCRIPT=<<END;
        // Ask a silly question
        function riddle_me_this() {
           var r = prompt("What walks on four legs in the morning, " +
                         "two legs in the afternoon, " +
                         "and three legs in the evening?");
           response(r);
        }
        // Get a silly answer
        function response(answer) {
           if (answer == "man")
              alert("Right you are!");
           else
              alert("Wrong!  Guess again.");
        }
        END
        
        print $query->start_html(-title=>'The Riddle of the Sphinx',
                                 -script=>$JSCRIPT);
        

  Netscape 3.0 and higher allows you to place the JavaScript code in an external document and refer to it by URL. This allows you to keep the JavaScript code in a file or CGI script rather than cluttering up each page with the source. Netscape 3.X-4.X and Internet Explorer 3.X-4.X also recognize a "language" parameter that allows you to use other languages, such as VBScript and PerlScript (yes indeed!) To use these attributes pass a HASH reference in the -script parameter containing one or more of the keys language, src, or code. Here's how to refer to an external script URL:

        print $q->start_html(-title=>'The Riddle of the Sphinx',
  			   -script=>{-language=>'JavaScript',
                                     -src=>'/javascript/sphinx.js'}
                                );
       

  Here's how to refer to scripting code incorporated directly into the page:

       print $q->start_html(-title=>'The Riddle of the Sphinx',
                            -script=>{-language=>'PerlScript',
                                      -code=>'print "hello world!\n;"'}
                               );
       

  A final feature allows you to incorporate multiple <SCRIPT> sections into the header. Just pass the list of script sections as an array reference. This allows you to specify different source files for different dialects of JavaScript. Example:

       print $q->start_html(-title=>'The Riddle of the Sphinx',
                            -script=>[
                                      { -language => 'JavaScript1.0',
                                        -src      => '/javascript/utilities10.js'
                                      },
                                      { -language => 'JavaScript1.1',
                                        -src      => '/javascript/utilities11.js'
                                      },
                                      { -language => 'JavaScript1.2',
                                        -src      => '/javascript/utilities12.js'
                                      },
                                      { -language => 'JavaScript28.2',
                                        -src      => '/javascript/utilities219.js'
                                      }
                                   ]
                               );
       

  (If this looks a bit extreme, take my advice and stick with straight CGI scripting.)

• A -noScript parameter to pass some HTML that will be displayed in browsers that do not have JavaScript (or have JavaScript turned off).
• -onLoad and -onUnload parameters to register JavaScript event handlers to be executed when the page generated by your script is opened and closed respectively. Example:

        print $query->start_html(-title=>'The Riddle of the Sphinx',
                                    -script=>$JSCRIPT,
                                    -onLoad=>'riddle_me_this()');
        

  See JavaScripting for more details.
• Any additional attributes you want to incorporate into the <BODY> tag (as many as you like). This is a good way to incorporate other Netscape extensions, such as background color and wallpaper pattern. (The example above sets the page background to a vibrant blue.) You can use this feature to take advantage of new HTML features without waiting for a CGI.pm release.

Ending an HTML Document

  print $query->end_html

Other HTML Tags

To see the list of HTML tags that are supported, open up the CGI.pm file and look at the functions defined in the %EXPORT_TAGS array.

Unpaired Tags

   print $query->hr;

Paired Tags

   print $query->em("What a silly art exhibit!");

You can pass as many text arguments as you like: they'll be concatenated together with spaces. This allows you to create nested tags easily:

   print $query->h3("The",$query->em("silly"),"art exhibit");

   <h3>The <em>silly</em> art exhibit</h3>

When used in conjunction with the import facility, the HTML shortcuts can make CGI scripts easier to read. For example:

   use CGI qw/:standard/;
   print h1("Road Guide"),
         ol(
          li(a({href=>"start.html"},"The beginning")),
          li(a({href=>"middle.html"},"The middle")),
          li(a({href=>"end.html"},"The end"))
         );

Most HTML tags are represented as lowercase function calls. There are a few exceptions:

1. The <tr> tag used to start a new table row conflicts with the perl translate function tr(). Use TR() or Tr() instead.
2. The <param> tag used to pass parameters to an applet conflicts with CGI's own param() method. Use PARAM() instead.
3. The <select> tag used to create selection lists conflicts with Perl's select() function. Use Select() instead.
4. The <sub> tag used to create subscripts conflicts wit Perl's operator for creating subroutines. Use Sub() instead.

Tags with Attributes

   use CGI qw/:standard/;
   print a({-href=>"bad_art.html"},"Jump to the silly exhibit");

   <A HREF="bad_art.html">Jump to the silly exhibit</A>

   print img {src=>'fred.gif',align=>'LEFT'};

   <IMG ALIGN="LEFT" SRC="fred.gif">

   print ol({compact=>undef},li('one'),li('two'),li('three'));

Distributive HTML Tags and Tables

print ul(
        li({-type=>'disc'},['Sneezy','Doc','Sleepy','Happy']);
      );

<UL>
  <LI TYPE="disc">Sneezy</LI>
  <LI TYPE="disc">Doc</LI>
  <LI TYPE="disc">Sleepy</LI>
  <LI TYPE="disc">Happy</LI>
</UL>

use CGI qw/:standard :html3/;
print table({-border=>undef},
        caption(strong('When Should You Eat Your Vegetables?')),
        Tr({-align=>CENTER,-valign=>TOP},
        [
           th(['','Breakfast','Lunch','Dinner']),
           th('Tomatoes').td(['no','yes','yes']),
           th('Broccoli').td(['no','no','yes']),
           th('Onions').td(['yes','yes','yes'])
        ]
      )
);

If you want to produce tables programatically, you can do it this way:

use CGI qw/:standard :html3/;
@values = (1..5);

@headings = ('N','N'.sup('2'),'N'.sup('3'));
@rows = th(\@headings);
foreach $n (@values) {
   push(@rows,td([$n,$n**2,$n**3]));
}
print table({-border=>undef,-width=>'25%'},
            caption(b('Wow.  I can multiply!')),
            Tr(\@rows)
           );

Creating Forms

General note 2. The default values that you specify for the forms are only used the first time the script is invoked. If there are already values present in the query string, they are used, even if blank.

If you want to change the value of a field from its previous value, you have two choices:

1. call the param() method to set it.
2. use the -override (alias -force) parameter. (This is a new feature in 2.15) This forces the default value to be used, regardless of the previous value of the field:

          print $query->textfield(-name=>'favorite_color',
                                  -default=>'red',
   			       -override=>1);
          

1. Create a special defaults button using the defaults() method.
2. Create a hypertext link that calls your script without any parameters.

General note 4. By popular demand, the text and labels that you provide for form elements are escaped according to HTML rules. This means that you can safely use "<CLICK ME>" as the label for a button. However, this behavior may interfere with your ability to incorporate special HTML character sequences, such as &Aacute; (Á) into your fields. If you wish to turn off automatic escaping, call the autoEscape() method with a false value immediately after creating the CGI object:

     $query = new CGI;
     $query->autoEscape(0);

General note 5. Some of the form-element generating methods return multiple tags. In a scalar context, the tags will be concatenated together with spaces, or whatever is the current value of the $" global. In a list context, the methods will return a list of elements, allowing you to modify them if you wish. Usually you will not notice this behavior, but beware of this:

    printf("%s\n",$query->end_form())

Form Elements

Creating An Isindex Tag

   print $query->isindex($action);

Starting And Ending A Form

   print $query->startform($method,$action,$encoding);
     ...various form stuff...
   print $query->endform;

The form encoding supports the "file upload" feature of Netscape 2.0 (and higher) and Internet Explorer 4.0 (and higher). The form encoding tells the browser how to package up the contents of the form in order to transmit it across the Internet. There are two types of encoding that you can specify:

application/x-www-form-urlencoded

This is the type of encoding used by all browsers prior to Netscape 2.0. It is compatible with many CGI scripts and is suitable for short fields containing text data. For your convenience, CGI.pm stores the name of this encoding type in $CGI::URL_ENCODED.

multipart/form-data

This is the newer type of encoding introduced by Netscape 2.0. It is suitable for forms that contain very large fields or that are intended for transferring binary data. Most importantly, it enables the "file upload" feature of Netscape 2.0 forms. For your convenience, CGI.pm stores the name of this encoding type in CGI::MULTIPART()

Forms that use this type of encoding are not easily interpreted by CGI scripts unless they use CGI.pm or another library that knows how to handle them. Unless you are using the file upload feature, there's no particular reason to use this type of encoding.

If you plan to make use of the JavaScript features, you can provide startform() with the optional -name and/or -onSubmit parameters. -name has no effect on the display of the form, but can be used to give the form an identifier so that it can be manipulated by JavaScript functions. Provide the -onSubmit parameter in order to register some JavaScript code to be performed just before the form is submitted. This is useful for checking the validity of a form before submitting it. Your JavaScript code should return a value of "true" to let Netscape know that it can go ahead and submit the form, and "false" to abort the submission.

Starting a Form that Uses the "File Upload" Feature

   print $query->start_multipart_form($method,$action,$encoding);
     ...various form stuff...
   print $query->endform;

Creating A Text Field

  Named parameter style
  print $query->textfield(-name=>'field_name',
	                    -default=>'starting value',
	                    -size=>50,
	                    -maxlength=>80);

   Old style
  print $query->textfield('foo','starting value',50,80);

• The first parameter (-name) is the required name for the field.
• The optional second parameter (-default) is the starting value for the field contents.
• The optional third parameter (-size) is the size of the field in characters.
• The optional fourth parameter (-maxlength) is the maximum number of characters the field will accomodate.

When the form is processed, the value of the text field can be retrieved with:

      $value = $query->param('foo');

JavaScripting: You can also provide -onChange, -onFocus, -onBlur, -onMouseOver, -onMouseOut and -onSelect parameters to register JavaScript event handlers.

Creating A Big Text Field

   Named parameter style
   print $query->textarea(-name=>'foo',
	 		  -default=>'starting value',
	                  -rows=>10,
	                  -columns=>50);

   Old style
   print $query->textarea('foo','starting value',10,50);

JavaScripting: Like textfield(), you can provide -onChange, -onFocus, -onBlur, -onMouseOver, -onMouseOut and -onSelect parameters to register JavaScript event handlers.

Creating A Password Field

   Named parameter style
   print $query->password_field(-name=>'secret',
				-value=>'starting value',
				-size=>50,
				-maxlength=>80);

   Old style
   print $query->password_field('secret','starting value',50,80);

Creating a File Upload Field

    Named parameters style
    print $query->filefield(-name=>'uploaded_file',
	                    -default=>'starting value',
	                    -size=>50,
	 		    -maxlength=>80);

    Old style
    print $query->filefield('uploaded_file','starting value',50,80);

• The first parameter (-name) is the required name for the field.
• The optional second parameter (-default) is the starting value for the file name. This field is currently ignored by all browsers, but there's always hope!
• The optional third parameter (-size) is the size of the field in characters.
• The optional fourth parameter (-maxlength) is the maximum number of characters the field will accomodate.

In order to take full advantage of the file upload facility you must use the new multipart form encoding scheme. You can do this either by calling startform() and specify an encoding type of $CGI::MULTIPART or by using the new start_multipart_form() method. If you don't use multipart encoding, then you'll be able to retreive the name of the file selected by the remote user, but you won't be able to access its contents.

When the form is processed, you can retrieve the entered filename by calling param().

       $filename = $query->param('uploaded_file');

The filename returned is also a file handle. You can read the contents of the file using standard Perl file reading calls:

	# Read a text file and print it out
	while (<$filename>) {
	   print;
        }

        # Copy a binary file to somewhere safe
        open (OUTFILE,">>/usr/local/web/users/feedback");
	while ($bytesread=read($filename,$buffer,1024)) {
	   print OUTFILE $buffer;
        }
       close $filename;

There are problems with the dual nature of the upload fields. If you use strict, then Perl will complain when you try to use a string as a filehandle. You can get around this by placing the file reading code in a block containing the no strict pragma. More seriously, it is possible for the remote user to type garbage into the upload field, in which case what you get from param() is not a filehandle at all, but a string.

To be safe, use the upload() function (new in version 2.47). When called with the name of an upload field, upload() returns a filehandle, or undef if the parameter is not a valid filehandle.

     $fh = $query->upload('uploaded_file');
     while (<$fh>) {
	   print;
     }

In an list context, upload() will return an array of filehandles. This makes it possible to create forms that use the same name for multiple upload fields.

This is the recommended idiom.

You can have several file upload fields in the same form, and even give them the same name if you like (in the latter case param() will return a list of file names). However, if the user attempts to upload several files with exactly the same name, CGI.pm will only return the last of them. This is a known bug.

When processing an uploaded file, CGI.pm creates a temporary file on your hard disk and passes you a file handle to that file. After you are finished with the file handle, CGI.pm unlinks (deletes) the temporary file. If you need to you can access the temporary file directly. Its name is stored inside the CGI object's "private" data, and you can access it by passing the file name to the tmpFileName() method:

       $filename = $query->param('uploaded_file');
       $tmpfilename = $query->tmpFileName($filename);

The temporary file will be deleted automatically when your program exits unless you manually rename it. On some operating systems (such as Windows NT), you will need to close the temporary file's filehandle before your program exits. Otherwise the attempt to delete the temporary file will fail.

You can set up a callback that will be called whenever a file upload is being read during the form processing. This is much like the UPLOAD_HOOK facility available in Apache::Request, with the exception that the first argument to the callback is an Apache::Upload object, here it's the remote filename.

 $q = CGI->new(\&hook);
 sub hook  {
        my ($filename, $buffer, $bytes_read, $data) = @_;
        print  "Read $bytes_read bytes of $filename\n";         
 }

If using the function-oriented interface, call the CGI::upload_hook() method before calling param() or any other CGI functions: CGI::upload_hook(\&hook,$data);

This method is not exported by default. You will have to import it explicitly if you wish to use it without the CGI:: prefix.

A potential problem with the temporary file upload feature is that the temporary file is accessible to any local user on the system. In previous versions of this module, the temporary file was world readable, meaning that anyone could peak at what was being uploaded. As of version 2.36, the modes on the temp file have been changed to read/write by owner only. Only the Web server and its CGI scripts can access the temp file. Unfortunately this means that one CGI script can spy on another! To make the temporary files really private, set the CGI global variable $CGI::PRIVATE_TEMPFILES to 1. Alternatively, call the built-in function CGI::private_tempfiles(1), or just use CGI qw/-private_tempfiles. The temp file will now be unlinked as soon as it is created, making it inaccessible to other users. The downside of this is that you will be unable to access this temporary file directly (tmpFileName() will continue to return a string, but you will find no file at that location.) Further, since PRIVATE_TEMPFILES is a global variable, its setting will affect all instances of CGI.pm if you are running mod_perl. You can work around this limitation by declaring $CGI::PRIVATE_TEMPFILES as a local at the top of your script.

On Windows NT, it is impossible to make a temporary file private. This is because Windows doesn't allow you to delete a file before closing it.

Usually the browser sends along some header information along with the text of the file itself. Currently the headers contain only the original file name and the MIME content type (if known). Future browsers might send other information as well (such as modification date and size). To retrieve this information, call uploadInfo(). It returns a reference to an associative array containing all the document headers. For example, this code fragment retrieves the MIME type of the uploaded file (be careful to use the proper capitalization for "Content-Type"!):

       $filename = $query->param('uploaded_file');
       $type = $query->uploadInfo($filename)->{'Content-Type'};
       unless ($type eq 'text/html') {
	  die "HTML FILES ONLY!";
       }

You can set up a callback that will be called whenever a file upload is being read during the form processing. This is much like the UPLOAD_HOOK facility available in Apache::Request, with the exception that the first argument to the callback is an Apache::Upload object, here it's the remote filename.

 $q = CGI->new(undef, \&hook, $data);

 sub hook
 {
        my ($filename, $buffer, $bytes_read, $data) = @_;
        print  "Read $bytes_read bytes of $filename\n";         
 }

JavaScripting: Like textfield(), filefield() accepts -onChange, -onFocus, -onBlur, -onMouseOver, -onMouseOut and -onSelect parameters to register JavaScript event handlers. Caveats and potential problems in the file upload feature.

Creating A Popup Menu

  Named parameter style
  print $query->popup_menu(-name=>'menu_name',
                            -values=>[qw/eenie meenie minie/], 
			    -labels=>{'eenie'=>'one',
                                         'meenie'=>'two',
                                         'minie'=>'three'},
	                    -default=>'meenie');

  print $query->popup_menu(-name=>'menu_name',
			    -values=>['eenie','meenie','minie'],
	                    -default=>'meenie');
  
  Old style
  print $query->popup_menu('menu_name',
                              ['eenie','meenie','minie'],'meenie',
                              {'eenie'=>'one','meenie'=>'two','minie'=>'three'});

• The required first argument (-name) is the menu's name.
• The required second argument (-values) is an array reference containing the list of menu items in the menu. You can pass the method an anonymous array, as shown in the example, or a reference to a named array, such as \@foo. If you pass a HASH reference, the keys will be used for the menu values, and the values will be used for the menu labels (see -labels below). However, the menu values will be in arbitrary order.
• The optional third parameter (-default) is the name of the default menu choice. If not specified, the first item will be the default. The value of the previous choice will be maintained across queries.
• The optional fourth parameter (-labels) allows you to pass a reference to an associative array containing user-visible labels for one or more of the menu items. You can use this when you want the user to see one menu string, but have the browser return your program a different one. If you don't specify this, the value string will be used instead ("eenie", "meenie" and "minie" in this example). This is equivalent to using a hash reference for the -values parameter.

     $popup_menu_value = $query->param('menu_name');

Creating A Scrolling List

   Named parameter style
   print $query->scrolling_list(-name=>'list_name',
                                -values=>['eenie','meenie','minie','moe'],
                                -default=>['eenie','moe'],
	                        -size=>5,
	                        -multiple=>'true',
                                -labels=>\%labels);

   Old style
   print $query->scrolling_list('list_name',
                                ['eenie','meenie','minie','moe'],
                                ['eenie','moe'],5,'true',
                                \%labels);

• The first and second arguments (-name, -values)are the list name and values, respectively. As in the popup menu, the second argument should be an array reference or hash reference. In the latter case, the values of the hash are used as the human-readable labels in the list.
• The optional third argument (-default)can be either a reference to a list containing the values to be selected by default, or can be a single value to select. If this argument is missing or undefined, then nothing is selected when the list first appears.
• The optional fourth argument (-size) is the display size of the list.
• The optional fifth argument (-multiple) can be set to true to allow multiple simultaneous selections.
• The option sixth argument (-labels) can be used to assign user-visible labels to the list items different from the ones used for the values as above. This is equivalent to passing a hash reference to -values. In this example we assume that an associative array %labels has already been created.

     @selected = $query->param('list_name');

Creating A Group Of Related Checkboxes

   Named parameter style
   print $query->checkbox_group(-name=>'group_name',
                                -values=>['eenie','meenie','minie','moe'],
                                -default=>['eenie','moe'],
	                        -linebreak=>'true',
	                        -labels=>\%labels);

   Old Style
   print $query->checkbox_group('group_name',
                                ['eenie','meenie','minie','moe'],
                                ['eenie','moe'],'true',\%labels);

   HTML3 Browsers Only
   print $query->checkbox_group(-name=>'group_name',
                                -values=>['eenie','meenie','minie','moe'],
                                -rows=>2,-columns=>2);

• The first and second arguments (-name, -values) are the checkbox name and values, respectively. As in the popup menu, the second argument should be an array reference or a hash reference. These values are used for the user-readable labels printed next to the checkboxes as well as for the values passed to your script in the query string.
• The optional third argument (-default) can be either a reference to a list containing the values to be checked by default, or can be a single value to checked. If this argument is missing or undefined, then nothing is selected when the list first appears.
• The optional fourth argument (-linebreak) can be set to true to place line breaks between the checkboxes so that they appear as a vertical list. Otherwise, they will be strung together on a horizontal line. When the form is procesed, all checked boxes will be returned as a list under the parameter name 'group_name'. The values of the "on" checkboxes can be retrieved with:
• The optional fifth argument (-labels) is a reference to an hash of checkbox labels. This allows you to use different strings for the user-visible button labels and the values sent to your script. In this example we assume that an associative array %labels has previously been created. This is equivalent to passing a hash reference to -values. If you don't use -nolabels, CGI.pm will add HTML label tag around each checkbox and its label, so a browser can identify the text as form element label properly.
• The optional parameter -nolabels can be used to suppress the printing of labels next to the button. This is useful if you want to capture the button elements individually and use them inside labeled HTML3 tables.
• Browsers that understand HTML3 tables (such as Netscape) can take advantage of the optional parameters -rows, and -columns. These parameters cause checkbox_group() to return an HTML3 compatible table containing the checkbox group formatted with the specified number of rows and columns. You can provide just the -columns parameter if you wish; checkbox_group will calculate the correct number of rows for you.

  To include row and column headings in the returned table, you can use the -rowheaders and -colheaders parameters. Both of these accept a pointer to an array of headings to use. The headings are just decorative. They don't reorganize the interpetation of the checkboxes -- they're still a single named unit.

  When viewed with browsers that don't understand HTML3 tables, the -rows and -columns parameters will leave you with a group of buttons that may be awkwardly formatted but still useable. However, if you add row and/or column headings, the resulting text will be very hard to read.

     @turned_on = $query->param('group_name');

       @h = $query->checkbox_group(-name=>'choice',
                                    -value=>['fee','fie','foe'],
                                    -nolabels=>1);
       create_nice_table(@h);

Creating A Standalone Checkbox

   Named parameter list
   print $query->checkbox(-name=>'checkbox_name',
			   -checked=>'checked',
		           -value=>'TURNED ON',
		           -label=>'Turn me on');

   Old style
   print $query->checkbox('checkbox_name',1,'TURNED ON','Turn me on');

• The first parameter (-name is the required name for the checkbox. It will also be used for the user-readable label printed next to the checkbox.
• The optional second parameter (-checked specifies that the checkbox is turned on by default. Aliases for this parameter are -selected and -on.
• The optional third parameter (-value specifies the value of the checkbox when it is checked. If not provided, the word "on" is assumed.
• The optional fourth parameter (-label assigns a user-visible label to the button. If not provided, the checkbox's name will be used. CGI.pm will add HTML label tag around the checkbox and its label, so a browser can identify the text as form element label properly.

     $turned_on = $query->param('checkbox_name');

Creating A Radio Button Group

   Named parameter style
   print $query->radio_group(-name=>'group_name',
			     -values=>['eenie','meenie','minie'],
                             -default=>'meenie',
			     -linebreak=>'true',
			     -labels=>\%labels);

   Old style
   print $query->radio_group('group_name',['eenie','meenie','minie'],
                                          'meenie','true',\%labels);

   HTML3-compatible browsers only
   print $query->radio_group(-name=>'group_name',
                                -values=>['eenie','meenie','minie','moe'],
	                        -rows=>2,-columns=>2);

• The first argument (-name is the name of the group and is required.
• The second argument (-values is the list of values for the radio buttons. The values and the labels that appear on the page are identical. Pass an array reference in the second argument, either using an anonymous array, as shown, or by referencing a named array as in \@foo. You may also use a hash reference in order to produce human-readable labels that are different from the values that will be returned as parameters to the CGI script.
• The optional third parameter (-default is the value of the default button to turn on. If not specified, the first item will be the default. Specify some nonexistent value, such as "-" if you don't want any button to be turned on.
• The optional fourth parameter (-linebreak can be set to 'true' to put line breaks between the buttons, creating a vertical list.
• The optional fifth parameter (-labels specifies an associative array containing labels to be printed next to each button. If not provided the button value will be used instead. This example assumes that the associative array %labels has already been defined. This is equivalent to passing a hash reference to -values. If you don't use -nolabels, CGI.pm will add HTML label tag around each radio button and its label, so a browser can identify the text as form element label properly.
• The optional parameter -nolabels can be used to suppress the printing of labels next to the button. This is useful if you want to capture the button elements individually and use them inside labeled HTML3 tables.
• Browsers that understand HTML3 tables (such as Netscape) can take advantage of the optional parameters -rows, and -columns. These parameters cause radio_group() to return an HTML3 compatible table containing the radio cluster formatted with the specified number of rows and columns. You can provide just the -columns parameter if you wish; radio_group will calculate the correct number of rows for you.

  To include row and column headings in the returned table, you can use the -rowheader and -colheader parameters. Both of these accept a pointer to an array of headings to use. The headings are just decorative. They don't reorganize the interpetation of the radio buttons -- they're still a single named unit.

  When viewed with browsers that don't understand HTML3 tables, the -rows and -columns parameters will leave you with a group of buttons that may be awkwardly formatted but still useable. However, if you add row and/or column headings, the resulting text will be very hard to read.

       $which_radio_button = $query->param('group_name');

       @h = $query->radio_group(-name=>'choice',
                                 -value=>['fee','fie','foe'],
                                 -nolabels=>1);
       create_nice_table(@h);

JavaScripting: You can provide an -onClick parameter to register some JavaScript code to be performed every time the user clicks on any of the buttons in the group.

Creating A Submit Button

   Named parameter style
   print $query->submit(-name=>'button_name',
		        -value=>'value');

  Old style
  print $query->submit('button_name','value');

• The first argument (-nameis optional. You can give the button a name if you have several submission buttons in your form and you want to distinguish between them.
• The second argument (-valueis also optional. This gives the button a value that will be passed to your script in the query string, and will also appear as the user-visible label.

  You can figure out which of several buttons was pressed by using different values for each one:

      $which_one = $query->param('button_name');
  

• You can use -label as an alias for -value. I always get confused about which of -name and -value changes the user-visible label on the button.

Creating A Reset Button

  print $query->reset

Creating A Defaults Button

  print $query->defaults('button_label')

Creating A Hidden Field

   Named parameter style
   print $query->hidden(-name=>'hidden_name',
                        -default=>['value1','value2'...]);

   Old style
   print $query->hidden('hidden_name','value1','value2'...);

• The first argument (-name) is required and specifies the name of this field.
• The second and subsequent arguments specify the value for the hidden field. This is a quick and dirty way of passing perl arrays through forms. If you use the named parameter style, you must provide the parameter -default and an array reference here.

As of version 2.0 I have changed the behavior of hidden fields once again. Read this if you use hidden fields.

Hidden fields used to behave differently from all other fields: the provided default values always overrode the "sticky" values. This was the behavior people seemed to expect, however it turns out to make it harder to write state-maintaining forms such as shopping cart programs. Therefore I have made the behavior consistent with other fields.

Just like all the other form elements, the value of a hidden field is "sticky". If you want to replace a hidden field with some other values after the script has been called once you'll have to do it manually before writing out the form element:

     $query->param('hidden_name','new','values','here');
     print $query->hidden('hidden_name');

    $hidden_value = $query->param('hidden_name');
            -or (for values created with arrays)-
    @hidden_values = $query->param('hidden_name');

Creating a Clickable Image Button

   Named parameter style
   print $query->image_button(-name=>'button_name',
                              -src=>'/images/NYNY.gif',
                              -align=>'MIDDLE');	

   Old style
   print $query->image_button('button_name','/source/URL','MIDDLE');

• The first argument(-name is required and specifies the name of this field.
• The second argument (-srcspecifies the URL of the image to display. It must be one of the types supported by inline images (e.g. GIF), but can be any local or remote URL.
• The third argument (-alignis anything you might want to use in the ALIGN attribute, such as TOP, BOTTOM, LEFT, RIGHT or MIDDLE. This field is optional.

    $x = $query->param('button_name.x');
    $y = $query->param('button_name.y');

Creating a JavaScript Button

   Named parameter style
   print $query->button(-name=>'button1',
                           -value=>'Click Me',
                           -onClick=>'doButton(this)');	

   Old style
   print $query->image_button('button1','Click Me','doButton(this)');

• The first argument(-name is required and specifies the name of this field.
• The second argument (-value gives the button a value, and will be used as the user-visible label on the button.
• The third argument (-onClick is any valid JavaScript code. It's usually a call to a JavaScript function defined somewhere else (see the start_html() method), but can be any JavaScript you like. Multiple lines are allowed, but you must be careful not to include any double quotes in the JavaScript text.

Controlling HTML Autoescaping

Use

    $query->autoEscape(0);

    $query->autoEscape(1);

Importing CGI Methods

use CGI qw(:standard);

use CGI;
$dinner = $query->param('entree');

use CGI qw(:standard);
$dinner = param('entree');

print $query->start_form,
      "Check here if you're happy: ",
      $query->checkbox(-name=>'happy',-value=>'Y',-checked=>1),
      "<P>",
      $query->submit,
      $query->end_form;

print start_form,
      "Check here if you're happy: ",
      checkbox(-name=>'happy',-value=>'Y',-checked=>1),
      p,
      submit,
      end_form;

$CGI::Q;

The use CGI statement is used to import method names into the current name space. There is a slight overhead for each name you import, but ordinarily is nothing to worry about. You can import selected method names like this:

   use CGI qw(header start_html end_html);

use CGI qw(:cgi :html2);

:cgi

These are all the tags that support one feature or another of the CGI protocol, including param(), path_info(), cookie(), request_method(), header() and the like.

:form

These are all the form element-generating methods, including start_form(), textfield(), etc.

:html2

These are HTML2-defined shortcuts such as br(), p() and head(). It also includes such things as start_html() and end_html() that aren't exactly HTML2, but are close enough.

:html3

These contain various HTML3 tags for tables, frames, super- and subscripts, applets and other objects.

:html4

These contain various HTML4 tags, including table headers and footers.

:netscape

These are Netscape extensions not included in the HTML3 category including blink() and center().

:html

These are all the HTML generating shortcuts, comprising the union of html2, html3, and netscape.

:multipart

These are various functions that simplify creating documents of the various multipart MIME types, and are useful for implementing server push.

:standard

This is the union of html2, html3, html4, form, and :cgi.

:all

This imports all the public methods into your namespace!

Pragmas

-any

When you use CGI -any, then any method that the query object doesn't recognize will be interpreted as a new HTML tag. This allows you to support the next ad hoc Netscape or Microsoft HTML extension. For example, to support Netscape's latest tag, <GRADIENT> (which causes the user's desktop to be flooded with a rotating gradient fill until his machine reboots), you can use something like this:

      use CGI qw(-any);
      $q=new CGI;
      print $q->gradient({speed=>'fast',start=>'red',end=>'blue'});
      

Since using any causes any mistyped method name to be interpreted as an HTML tag, use it with care or not at all.

-compile

This causes the indicated autoloaded methods to be compiled up front, rather than deferred to later. This is useful for scripts that run for an extended period of time under FastCGI or mod_perl, and for those destined to be crunched by Malcom Beattie's Perl compiler. Use it in conjunction with the methods or method familes you plan to use.

      use CGI qw(-compile :standard :html3);
      

or even

      use CGI qw(-compile :all);
      

Note that using the -compile pragma in this way will always have the effect of importing the compiled functions into the current namespace. If you want to compile without importing use the compile() method instead.

-autoload

Overrides the autoloader so that any function in your program that is not recognized is referred to CGI.pm for possible evaluation. This allows you to use all the CGI.pm functions without adding them to your symbol table, which is of concern for mod_perl users who are worried about memory consumption. Warning: when -autoload is in effect, you cannot use "poetry mode" (functions without the parenthesis). Use hr() rather than hr, or add something like use subs qw/hr p header/ to the top of your script.

-nosticky

Turns off "sticky" behavior in fill-out forms. Every form element will act as if you passed -override.

-no_xhtml

By default, CGI.pm versions 2.69 and higher emit XHTML (http://www.w3.org/TR/xhtml1/). The -no_xhtml pragma disables this feature. Thanks to Michalis Kabrianis <kabrianis@hellug.gr> for this feature.

-nph

This makes CGI.pm produce a header appropriate for an NPH (no parsed header) script. You may need to do other things as well to tell the server that the script is NPH. See the discussion of NPH scripts below.

-oldstyle_urls

Separate the name=value pairs in CGI parameter query strings emitted by self_url() and query_string() with ampersands. Otherwise, CGI.pm emits HTML-compliant semicolons. If you use this form, be sure to escape ampersands into HTML entities with escapeHTML. Example:

      $href = $q->self_url();
      $href = escapeHTML($href);
      print I'm talking to myself
      

-newstyle_urls

Separate the name=value pairs in CGI parameter query strings with semicolons rather than ampersands. For example:

      name=fred;age=24;favorite_color=3
      

As of version 2.64, this is the default style.

-no_debug

This turns off the command-line processing features. If you want to run a CGI.pm script from the command line to produce HTML, and you don't want it interpreting arguments on the command line as CGI name=value arguments, then use this pragma:

      use CGI qw(-no_debug :standard);
      

-debug

This turns on full debugging. In addition to reading CGI arguments from the command-line processing, CGI.pm will pause and try to read arguments from STDIN, producing the message "(offline mode: enter name=value pairs on standard input)" features.

See debugging for more details.

-private_tempfiles

CGI.pm can process uploaded file. Ordinarily it spools the uploaded file to a temporary directory, then deletes the file when done. However, this opens the risk of eavesdropping as described in the file upload section. Another CGI script author could peek at this data during the upload, even if it is confidential information. On Unix systems, the -private_tempfiles pragma will cause the temporary file to be unlinked as soon as it is opened and before any data is written into it, eliminating the risk of eavesdropping.

Special Forms for Importing HTML-Tag Functions

  print h1('Level 1 Header');

  <H1>Level 1 Header</H1>

  print start_h1,'Level 1 Header',end_h1;

Example:

  use CGI qw/:standard *table start_ul/;

1. start_table() (generates a <TABLE> tag)
2. end_table() (generates a </TABLE> tag)
3. start_ul() (generates a <UL> tag)
4. end_ul() (generates a </UL> tag)

AUTOESCAPING HTML

$escaped_string = escapeHTML("unescaped string");

Provided that you have specified a character set of ISO-8859-1 (the default), the standard HTML escaping rules will be used. The "<" character becomes "&lt;", ">" becomes "&gt;", "&" becomes "&amp;", and the quote character becomes "&quot;". In addition, the hexadecimal 0x8b and 0x9b characters, which many windows-based browsers interpret as the left and right angle-bracket characters, are replaced by their numeric HTML entities ("&#139" and "&#155;"). If you manually change the charset, either by calling the charset() method explicitly or by passing a -charset argument to header(), then all characters will be replaced by their numeric entities, since CGI.pm has no lookup table for all the possible encodings.

Autoescaping does not apply to other HTML-generating functions, such as h1(). You should call escapeHTML() yourself on any data that is passed in from the outside, such as nasty text that people may enter into guestbooks.

To change the character set, use charset(). To turn autoescaping off completely, use autoescape():

$charset = charset([$charset]);  # Get or set the current character set.

$flag = autoEscape([$flag]);     # Get or set the value of the autoescape flag.

PRETTY-PRINTING HTML

Optional Utility Functions

escape(), unescape()

use CGI qw/escape unescape/;
$q = escape('This $string contains ~wonderful~ characters');
$u = unescape($q);

escapeHTML(), unescapeHTML()

use CGI qw/escapeHTML unescapeHTML/;
$q = escapeHTML('This string is <illegal> html!');
$u = unescapeHTML($q);

compile()

use CGI ();
CGI->compile(':all');

Debugging

   my_script.pl keyword1 keyword2 keyword3

   my_script.pl keyword1+keyword2+keyword3

   my_script.pl name1=value1 name2=value2

   my_script.pl name1=value1&name2=value2

   % my_script.pl
   first_name=fred
   last_name=flintstone
   occupation='granite miner'
   ^D

When debugging, you can use quotation marks and the backslash character to escape spaces and other funny characters in exactly the way you would in the shell (which isn't surprising since CGI.pm uses "shellwords.pl" internally). This lets you do this sort of thing:

    my_script.pl 'name 1=I am a long value' name\ 2=two\ words

If you run a script that uses CGI.pm from the command line and fail to provide it with any arguments, it will print out the line

(offline mode: enter name=value pairs on standard input)

You can suppress this behavior in any of the following ways:

1. Call the script with an empty parameter.

Example:

      my_script.pl ''
      

2. Redirect standard input from /dev/null or an empty file.

Example:

      my_script.pl </dev/null
      

3. Include "-no_debug" in the list of symbols to import on the "use" line.

Example:

      use CGI qw/:standard -no_debug/;
      

Dumping Out All The Name/Value Pairs

   print $query->Dump

   <UL>
   <LI>name1
       <UL>
       <LI>value1
       <LI>value2
       </UL>
   <LI>name2
       <UL>
       <LI>value1
       </UL>
   </UL>

   print "<H2>Current Contents:</H2>\n$query\n";

HTTP Session Variables

Accept()

Return a list of MIME types that the remote browser accepts. If you give this method a single argument corresponding to a MIME type, as in $query->Accept('text/html'), it will return a floating point value corresponding to the browser's preference for this type from 0.0 (don't want) to 1.0. Glob types (e.g. text/*) in the browser's accept list are handled correctly. Note the capitalization of the initial letter. This avoids conflict with the Perl built-in accept().

auth_type()

Return the authorization type, if protection is active. Example "Basic".

raw_cookie()

Returns the "magic cookie" maintained by Netscape 1.1 and higher in a raw state. You'll probably want to use cookie() instead, which gives you a high-level interface to the cookie functions. Called with no parameters, raw_cookie() returns the entire cookie structure, which may consist of several cookies appended together (you can recover individual cookies by splitting on the "; " sequence. Called with the name of a cookie, returns the unescaped value of the cookie as set by the server. This may be useful for retrieving cookies that your script did not set.

path_info()

Returns additional path information from the script URL. E.G. fetching /cgi-bin/your_script/additional/stuff will result in $query->path_info() returning "/additional/stuff". In addition to reading the path information, you can set it by giving path_info() an optional string argument. The argument is expected to begin with a "/". If not present, one will be added for you. The new path information will be returned by subsequent calls to path_info(), and will be incorporated into the URL generated by self_url().

path_translated()

As per path_info() but returns the additional path information translated into a physical path, e.g. "/usr/local/etc/httpd/htdocs/additional/stuff". You cannot change the path_translated, nor will setting the additional path information change this value. The reason for this restriction is that the translation of path information into a physical path is ordinarily done by the server in a layer that is inaccessible to CGI scripts.

query_string()

Returns a query string suitable for maintaining state.

referer()

Return the URL of the page the browser was viewing prior to fetching your script. Not available for all browsers.

remote_addr()

Return the dotted IP address of the remote host.

remote_ident()

Return the identity-checking information from the remote host. Only available if the remote host has the identd daemon turned on.

remote_host()

Returns either the remote host name or IP address. if the former is unavailable.

remote_user()

Return the name given by the remote user during password authorization.

request_method()

Return the HTTP method used to request your script's URL, usually one of GET, POST, or HEAD.

script_name()

Return the script name as a partial URL, for self-refering scripts.

server_name()

Return the name of the WWW server the script is running under.

server_software()

Return the name and version of the server software.

virtual_host()

When using the virtual host feature of some servers, returns the name of the virtual host the browser is accessing.

server_port()

Return the communications port the server is using.

virtual_port()

Like server_port() except that it takes virtual hosts into account.

user_agent()

Returns the identity of the remote user's browser software, e.g. "Mozilla/1.1N (Macintosh; I; 68K)"

user_name()

Attempts to obtain the remote user's name, using a variety of environment variables. This only works with older browsers such as Mosaic. Netscape does not reliably report the user name!

http()

Called with no arguments returns the list of HTTP environment variables, including such things as HTTP_USER_AGENT, HTTP_ACCEPT_LANGUAGE, and HTTP_ACCEPT_CHARSET, corresponding to the like-named HTTP header fields in the request. Called with the name of an HTTP header field, returns its value. Capitalization and the use of hyphens versus underscores are not significant.

For example, all three of these examples are equivalent:

   $requested_language = $q->http('Accept-language');
   $requested_language = $q->http('Accept_language');
   $requested_language = $q->http('HTTP_ACCEPT_LANGUAGE');

https()

The same as http(), but operates on the HTTPS environment variables present when the SSL protocol is in effect. Can be used to determine whether SSL is turned on.

HTTP Cookies

A cookie is a name=value pair much like the named parameters in a CGI query string. CGI scripts create one or more cookies and send them to the browser in the HTTP header. The browser maintains a list of cookies that belong to a particular Web server, and returns them to the CGI script during subsequent interactions.

In addition to the required name=value pair, each cookie has several optional attributes:

an expiration time

This is a time/date string (in a special GMT format) that indicates when a cookie expires. The cookie will be saved and returned to your script until this expiration date is reached if the user exits the browser and restarts it. If an expiration date isn't specified, the cookie will remain active until the user quits the browser.

Negative expiration times (e.g. "-1d") cause some browsers to delete the cookie from its persistent store. This is a poorly documented feature.

a domain

This is a partial or complete domain name for which the cookie is valid. The browser will return the cookie to any host that matches the partial domain name. For example, if you specify a domain name of ".capricorn.com", then the browser will return the cookie to Web servers running on any of the machines "www.capricorn.com", "www2.capricorn.com", "feckless.capricorn.com", etc. Domain names must contain at least two periods to prevent attempts to match on top level domains like ".edu". If no domain is specified, then the browser will only return the cookie to servers on the host the cookie originated from.

a path

If you provide a cookie path attribute, the browser will check it against your script's URL before returning the cookie. For example, if you specify the path "/cgi-bin", then the cookie will be returned to each of the scripts "/cgi-bin/tally.pl", "/cgi-bin/order.pl", and "/cgi-bin/customer_service/complain.pl", but not to the script "/cgi-private/site_admin.pl". By default, path is set to "/", which causes the cookie to be sent to any CGI script on your site.

a "secure" flag

If the "secure" attribute is set, the cookie will only be sent to your script if the CGI request is occurring on a secure channel, such as SSL.

    $cookie = $query->cookie(-name=>'sessionID',
			     -value=>'xyzzy',
			     -expires=>'+1h',
			     -path=>'/cgi-bin/database',
			     -domain=>'.capricorn.org',
			     -secure=>1);
    print $query->header(-cookie=>$cookie);

-name

The name of the cookie (required). This can be any string at all. Although Netscape limits its cookie names to non-whitespace alphanumeric characters, CGI.pm removes this restriction by escaping and unescaping cookies behind the scenes.

-value

The value of the cookie. This can be any scalar value, array reference, or even associative array reference. For example, you can store an entire associative array into a cookie this way:

	$cookie=$query->cookie(-name=>'family information',
                               -value=>\%childrens_ages);

-path

The optional partial path for which this cookie will be valid, as described above.

-domain

The optional partial domain for which this cookie will be valid, as described above.

-expires

The optional expiration date for this cookie. The format is as described in the section on the header() method:

	"+1h"  one hour from now
      

-secure

If set to true, this cookie will only be used within a secure SSL session.

	print $query->header(-cookie=>$my_cookie);

	$cookie1 = $query->cookie(-name=>'riddle_name',
                                  -value=>"The Sphynx's Question");
        $cookie2 = $query->cookie(-name=>'answers',
                                  -value=>\%answers);
        print $query->header(-cookie=>[$cookie1,$cookie2]);

	use CGI;
	$query = new CGI;
	%answers = $query->cookie('answers');
	# $query->cookie(-name=>'answers') works too!

	foreach $name ($query->cookie()) {
            print $query->cookie($name);
        }

The cookie and CGI namespaces are separate. If you have a parameter named 'answers' and a cookie named 'answers', the values retrieved by param() and cookie() are independent of each other. However, it's simple to turn a CGI parameter into a cookie, and vice-versa:

   # turn a CGI parameter into a cookie
   $c=$q->cookie(-name=>'answers',-value=>[$q->param('answers')]);
   # vice-versa
   $q->param(-name=>'answers',-value=>[$q->cookie('answers')]);

See the cookie.cgi example script for some ideas on how to use cookies effectively.

NOTE: There are some limitations on cookies. Here is what RFC2109, section 6.3, states:

   Practical user agent implementations have limits on the number and
   size of cookies that they can store.  In general, user agents' cookie
   support should have no fixed limits.  They should strive to store as
   many frequently-used cookies as possible.  Furthermore, general-use
   user agents should provide each of the following minimum capabilities
   individually, although not necessarily simultaneously:

      * at least 300 cookies

      * at least 4096 bytes per cookie (as measured by the size of the
        characters that comprise the cookie non-terminal in the syntax
        description of the Set-Cookie header)

      * at least 20 cookies per unique host or domain name

   User agents created for specific purposes or for limited-capacity
   devices should provide at least 20 cookies of 4096 bytes, to ensure
   that the user can interact with a session-based origin server.

   The information in a Set-Cookie response header must be retained in
   its entirety.  If for some reason there is inadequate space to store
   the cookie, it must be discarded, not truncated.

   Applications should use as few and as small cookies as possible, and
   they should cope gracefully with the loss of a cookie.

Table of contents

Support for Frames

1. You can provide the name of a new or preexisting frame in the startform() and start_multipart_form() methods using the -target parameter. When the form is submitted, the output will be redirected to the indicated frame:

         print $query->start_form(-target=>'result_frame');
         

2. You can direct the output of a script into a new window or into a preexisting named frame by providing the name of the frame as a -target argument in the header method. For example, the following code will pop up a new window and display the script's output:

         $query = new CGI;
         print $query->header(-target=>'_blank');
         

   This feature is a non-standard extension to HTTP which is supported by Netscape browsers, but not by Internet Explorer.

The examples directory contains a script called popup.cgi that demonstrates a simple popup window. frameset.cgi provides a skeleton script for creating side-by-side query/result frame sets.

Support for JavaScript

You'll need to know JavaScript in order to use it. The Netscape JavaScript manual contains a good tutorial and reference guide to the JavaScript programming language.

The usual way to use JavaScript is to define a set of functions in a <SCRIPT> block inside the HTML header and then to register event handlers in the various elements of the page. Events include such things as the mouse passing over a form element, a button being clicked, the contents of a text field changing, or a form being submitted. When an event occurs that involves an element that has registered an event handler, its associated JavaScript code gets called.

The elements that can register event handlers include the <BODY> of an HTML document, hypertext links, all the various elements of a fill-out form, and the form itself. There are a large number of events, and each applies only to the elements for which it is relevant. Here is a partial list:

onLoad

The browser is loading the current document. Valid in:

• The HTML <BODY> section only.

onUnload

The browser is closing the current page or frame. Valid for:

• The HTML <BODY> section only.

onSubmit

The user has pressed the submit button of a form. This event happens just before the form is submitted, and your function can return a value of false in order to abort the submission. Valid for:

• Forms only.

onClick

The mouse has clicked on an item in a fill-out form. Valid for:

• Buttons (including submit, reset, and image buttons)
• Checkboxes
• Radio buttons

onChange

The user has changed the contents of a field. Valid for:

• Text fields
• Text areas
• Password fields
• File fields
• Popup Menus
• Scrolling lists

onFocus

The user has selected a field to work with. Valid for:

• Text fields
• Text areas
• Password fields
• File fields
• Popup Menus
• Scrolling lists

onBlur

The user has deselected a field (gone to work somewhere else). Valid for:

• Text fields
• Text areas
• Password fields
• File fields
• Popup Menus
• Scrolling lists

onSelect

The user has changed the part of a text field that is selected. Valid for:

• Text fields
• Text areas
• Password fields
• File fields

onMouseOver

The mouse has moved over an element.

• Text fields
• Text areas
• Password fields
• File fields
• Popup Menus
• Scrolling lists

onMouseOut

The mouse has moved off an element.

• Text fields
• Text areas
• Password fields
• File fields
• Popup Menus
• Scrolling lists

   print $q->textfield(-name=>'age',-onChange=>"validateAge(this)");

Similarly, you can create a form that checks itself over for consistency and alerts the user if some essential value is missing by creating it this way:

   print $q->startform(-onSubmit=>"validateMe(this)");

The JavaScript "standard" is still evolving, which means that new handlers may be added in the future, or may be present in some browsers and not in others. You do not need to wait for a new version of CGI.pm to use new event handlers. Just like any other tag attribute they will produce syntactically correct HTML. For instance, if Microsoft invents a new event handler called onInterplanetaryDisaster, you can install a handler for it with:

print button(-name=>'bail out',-onInterPlaneteryDisaster=>"alert('uh oh')");

Limited Support for Cascading Style Sheets

CGI.pm has limited support for HTML3's cascading style sheets (css). To incorporate a stylesheet into your document, pass the start_html() method a -style parameter. The value of this parameter may be a scalar, in which case it is incorporated directly into a <STYLE> section, or it may be a hash reference. In the latter case you should provide the hash with one or more of -src or -code. -src points to a URL where an externally-defined stylesheet can be found. -code points to a scalar value to be incorporated into a <STYLE> section. Style definitions in -code override similarly-named ones in -src, hence the name "cascading."

You may also specify the MIME type of the stylesheet by including an optional -type parameter in the hash pointed to by -style. If not specified, the type defaults to 'text/css'.

To refer to a style within the body of your document, add the -class parameter to any HTML element:

print h1({-class=>'Fancy'},'Welcome to the Party');

print h1({-style=>'Color: red;'},'Welcome to Hell');

print span({-style=>'Color: red;'},
	       h1('Welcome to Hell'),
	       "Where did that handbasket get to?"
          );

You won't be able to do much with this unless you understand the CSS specification. A more intuitive subclassable library for cascading style sheets in Perl is in the works, but until then, please read the CSS specification at http://www.w3.org/pub/WWW/Style/ to find out how to use these features. Here's a final example to get you started.

use CGI qw/:standard :html3/;

#here's a stylesheet incorporated directly into the page
$newStyle=<<END;
<!-- 
    P.Tip {
	margin-right: 50pt;
	margin-left: 50pt;
        color: red;
    }
    P.Alert {
	font-size: 30pt;
        font-family: sans-serif;
      color: red;
    }
-->
END
print header();
print start_html( -title=>'CGI with Style',
                  -style=>{-src=>'http://www.capricorn.com/style/st1.css',
                  -code=>$newStyle}
	         );
print h1('CGI with Style'),
      p({-class=>'Tip'},
        "Better read the cascading style sheet spec before playing with this!"
        ),
      span({-style=>'color: magenta'},"Look Mom, no hands!",
        p(),
        "Whooo wee!"
      );
print end_html;

Pass an array reference to -code or -srcin order to incorporate multiple stylesheets into your document.

Should you wish to incorporate a verbatim stylesheet that includes arbitrary formatting in the header, you may pass a -verbatim tag to the -style hash, as follows:

print $q->start_html (-STYLE  =>  {-verbatim => '@import
url("/server-common/css/'.$cssFile.'");',
                      -src      =>  '/server-common/css/core.css'});

This will generate HTML like this:

<link rel="stylesheet" type="text/css"
 href="/server-common/css/core.css">

   <style type="text/css">
   @import url("/server-common/css/main.css");
   </style>

Any additional arguments passed in the -style value will be incorporated into the <link> tag. For example:

 start_html(-style=>{-src=>['/styles/print.css','/styles/layout.css'],
			  -media => 'all'});

<link rel="stylesheet" type="text/css" href="/styles/print.css" media="all"/>
<link rel="stylesheet" type="text/css" href="/styles/layout.css" media="all"/>

To make more complicated <link> tags, use the Link() function and pass it to start_html() in the -head argument, as in:

  @h = (Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/ss.css',-media=>'all'}),
        Link({-rel=>'stylesheet',-type=>'text/css',-src=>'/ss/fred.css',-media=>'paper'}));
  print start_html({-head=>\@h})

Using NPH Scripts

Servers use a variety of conventions for designating CGI scripts as NPH. IIS and many Unix servers look at the beginning of the script's name for the prefix "nph-".

CGI.pm supports NPH scripts with a special NPH mode. When in this mode, CGI.pm will output the necessary extra header information when the header() and redirect() methods are called.

Important: If you use the Microsoft Internet Information Server, you must designate your script as an NPH script. Otherwise many of CGI.pm's features, such as redirection and the ability to output non-HTML files, will fail. However, after applying Service Pack 6, NPH scripts do not work at all on IIS without a special patch from Microsoft. See Knowledgebase article Q280/3/31 Non-Parsed Headers Stripped From CGI Applications That Have nph- Prefix in Name

There are a number of ways to put CGI.pm into NPH mode:

In the use statement:

Simply add "-nph" to the list of symbols to be imported into your script:

      use CGI qw(:standard -nph)
      

By calling the nph() method:

Call nph() with a non-zero parameter at any point after using CGI.pm in your program.

      CGI->nph(1)
      

By using -nph parameters in the header() and redirect() statements:

      print $q->header(-nph=>1);
      

Advanced Techniques

A Script that Saves Some Information to a File and Restores It

#!/usr/local/bin/perl

use CGI;
$query = new CGI;

print $query->header;
print $query->start_html("Save and Restore Example");
print "<H1>Save and Restore Example</H1>\n";

# Here's where we take action on the previous request
&save_parameters($query)              if $query->param('action') eq 'save';
$query = &restore_parameters($query)  if $query->param('action') eq 'restore';

# Here's where we create the form
print $query->startform;
print "Popup 1: ",$query->popup_menu('popup1',['eenie','meenie','minie']),"\n";
print "Popup 2: ",$query->popup_menu('popup2',['et','lux','perpetua']),"\n";
print "<P>";
print "Save/restore state from file: ",$query->textfield('savefile','state.sav'),"\n";
print "<P>";
print $query->submit('action','save'),$query->submit('action','restore');
print $query->submit('action','usual query');
print $query->endform;

# Here we print out a bit at the end
print $query->end_html;

sub save_parameters {
    local($query) = @_;
    local($filename) = &clean_name($query->param('savefile'));
    if (open(FILE,">$filename")) {
	$query->save(FILE);
	close FILE;
	print "<STRONG>State has been saved to file $filename</STRONG>\n";
    } else {
	print "<STRONG>Error:</STRONG> couldn't write to file $filename: $!\n";
    }
}

sub restore_parameters {
    local($query) = @_;
    local($filename) = &clean_name($query->param('savefile'));
    if (open(FILE,$filename)) {
	$query = new CGI(FILE);  # Throw out the old query, replace it with a new one
	close FILE;
	print "<STRONG>State has been restored from file $filename</STRONG>\n";
    } else {
	print "<STRONG>Error:</STRONG> couldn't restore file $filename: $!\n";
    }
    return $query;
}


# Very important subroutine -- get rid of all the naughty
# metacharacters from the file name. If there are, we
# complain bitterly and die.
sub clean_name {
   local($name) = @_;
   unless ($name=~/^[\w\._-]+$/) {
      print "<STRONG>$name has naughty characters.  Only ";
      print "alphanumerics are allowed.  You can't use absolute names.</STRONG>";
      die "Attempt to use naughty characters";
   }
   return $name;
}

http://stein.cshl.org/software/boulder/

A Script that Uses Self-Referencing URLs to Jump to Internal Links

Many people have experienced problems with internal links on pages that have forms. Jumping around within the document causes the state of the form to be reset. A partial solution is to use the self_url() method to generate a link that preserves state information. This script illustrates how this works.

#!/usr/local/bin/perl

use CGI;
$query = new CGI;

# We generate a regular HTML file containing a very long list
# and a popup menu that does nothing except to show that we
# don't lose the state information.
print $query->header;
print $query->start_html("Internal Links Example");
print "<H1>Internal Links Example</H1>\n";

print "<A NAME=\"start\"></A>\n"; # an anchor point at the top

# pick a default starting value;
$query->param('amenu','FOO1') unless $query->param('amenu');

print $query->startform;
print $query->popup_menu('amenu',[('FOO1'..'FOO9')]);
print $query->submit,$query->endform;

# We create a long boring list for the purposes of illustration.
$myself = $query->self_url;
print "<OL>\n";
for (1..100) {
    print qq{<LI>List item #$_<A HREF="$myself#start">Jump to top</A>\n};
}
print "</OL>\n";

print $query->end_html;

Multiple forms on the same page

There is, however, a problem with maintaining the states of multiple forms. Because the browser only sends your script the parameters from the form in which the submit button was pressed, the state of all the other forms will be lost. One way to get around this, suggested in this example, is to use hidden fields to pass as much information as possible regardless of which form the user submits.

#!/usr/local/bin/perl
use CGI;

$query=new CGI;
print $query->header;
print $query->start_html('Multiple forms');
print "<H1>Multiple forms</H1>\n";

# form 1
print "<HR>\n";
print $query->startform;
print $query->textfield('text1'),$query->submit('submit1');
print $query->hidden('text2');  # pass information from the other form
print $query->endform;
print "<HR>\n";

# form 2
print $query->startform;
print $query->textfield('text2'),$query->submit('submit2');
print $query->hidden('text1');  # pass information from the other form
print $query->endform;
print "<HR>\n";
print $query->end_html;

Table of contents

Subclassing CGI.pm

If you use standard subclassing techniques and restrict yourself to using CGI.pm and its subclasses in the object-oriented manner, you'll have no problems. However, if you wish to use the function-oriented calls with your subclass, follow this model:

package MySubclass;
use vars qw(@ISA $VERSION);
require CGI;
@ISA = qw(CGI);
$VERSION = 1.0;

$CGI::DefaultClass = __PACKAGE__;
$AutoloadClass = 'CGI';

sub new {
   ....
}
1;

The second trick is to set the package variable $AutoloadClass to the string "CGI". This tells the CGI autoloader where to look for functions that are not defined. If you wish to override CGI's autoloader, set this to the name of your own package.

More information on extending CGI.pm can be found in my new book, The Official Guide to CGI.pm, which was published by John Wiley & Sons in April 1998. Check out the book's Web site, which contains multiple useful coding examples.

Table of contents

Using CGI.pm with mod_perl and FastCGI

FastCGI

FastCGI modules are available for the Apache and NCSA servers as well as for OpenMarket's own server. In order to use FastCGI with Perl you have to run a specially-modified version of the Perl interpreter. Precompiled Binaries and a patch kit are all available on OpenMarket's FastCGI web site.

To use FastCGI with CGI.pm, change your scripts as follows:

Old Script

#!/usr/local/bin/perl
use CGI qw(:standard);
print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;

New Script

#!/usr/local/fcgi/bin/perl
use CGI::Fast qw(:standard);

# Do time-consuming initialization up here.
while (new CGI::Fast) {
   print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;
}

mod_perl

1. Server launches a new Perl interpreter every time it needs to interpret a Perl script. This speeds CGI scripts significantly because there's no overhead for launching a new Perl process.
2. A "fast" mode in which the server launches your script at initialization time. You can load all your favorite modules (like CGI.pm!) at initialization time, greatly speeding things up.

Old Script

#!/usr/local/bin/perl
use CGI qw(:standard);
print header,
      start_html("CGI Script"),
      h1("CGI Script"),
      "Not much to see here",
      hr,
      address(a({href=>'/'},"home page"),  
      end_html;

New Script

#!/usr/bin/perl
use CGI::Apache qw(:standard);

print header,
    start_html("CGI Script"),
    h1("CGI Script"),
    "Not much to see here",
    hr,
    address(a({href=>'/'},"home page"),  
    end_html;
}

mod_perl comes with a small wrapper library named CGI::Switch that selects dynamically between using CGI and CGI::Apache. This library is no longer needed. However users of CGI::Switch can continue to use it without risk. Note that the "simple" interface to the CGI.pm functions does not work with CGI::Switch. You'll have to use the object-oriented versions (or use the sfio version of Perl!)

If you use CGI.pm in many of your mod_perl scripts, you may want to preload CGI.pm and its methods at server startup time. To do this, add the following line to httpd.conf:

PerlScript /home/httpd/conf/startup.pl

#!/usr/local/bin/perl

use CGI ();
CGI->compile(':all');

Table of contents

Migrating from cgi-lib.pl

When you call ReadParse(), CGI.pm creates an associative array named %in that contains the named CGI parameters. Multi-valued parameters are separated by "\0" characters in exactly the same way cgi-lib.pl does it. The function result is the number of parameters parsed. You can use this to determine whether the script is being called from a fill out form or not.

To port an old script to CGI.pm, you have to make just two changes:

Old Script

    require "cgi-lib.pl";
    ReadParse();
    print "The price of your purchase is $in{price}.\n";

New Script

    use CGI qw(:cgi-lib);
    ReadParse();
    print "The price of your purchase is $in{price}.\n";

   ReadParse(*Q);
   @partners = split("\0",$Q{'golf_partners'});

The associative array created by CGI::ReadParse() contains a special key 'CGI', which returns the CGI query object itself:

    ReadParse();
    $q = $in{CGI};
    print $q->textfield(-name=>'wow',
                        -value=>'does this really work?');

This allows you to add the more interesting features of CGI.pm to your old scripts without rewriting them completely. As an added benefit, the %in variable is actually tie()'d to the CGI object. Changing the CGI object using param() will dynamically change %in, and vice-versa.

cgi-lib.pl's @in and $in variables are not supported. In addition, the extended version of ReadParse() that allows you to spool uploaded files to disk is not available. You are strongly encouraged to use CGI.pm's file upload interface instead.

See cgi-lib_porting.html for more details on porting cgi-lib.pl scripts to CGI.pm.

Using the File Upload Feature

Known problems include:

1. Large file uploads may fail when using SSL version 2.0. This affects the Netscape servers and possibly others that use the SSL library. I have received reports that WebSite Pro suffers from this problem. This is a documented bug in the Netscape implementation of SSL and not a problem with CGI.pm.
2. If you try to upload a directory path with Unix Netscape, the browser will hang until you hit the "stop" button. I haven't tried to figure this one out since I think it's dumb of Netscape to allow this to happen at all.
3. If you create the CGI object in one package (e.g. "main") and then obtain the filehandle in a different package (e.g. "foo"), the filehandle will be accessible through "main" but not "foo". In order to use the filehandle, try the following contortion:

         $file = $query->param('file to upload');
         $file = "main::$file";
             ...
         

   I haven't found a way to determine the correct caller in this situation. I might add a readFile() method to CGI if this problem bothers enough people.

Frequent Problems

When you run a script from the command line, it says "offline mode: enter name=value pairs on standard input". What do I do now?

    first_name=Fred
    last_name=Flintstone
    city=Bedrock

If you want to run a CGI script from a script or batch file, and don't want this behavior, just pass it an empty parameter list like this:

     my_script.pl ''

     my_script.pl </dev/null

use CGI qw/:standard -no_debug/;

CGI.pm breaks when you use "use integer"

Due to problems that integer.pm has with unary negation, calls to CGI.pm that use the -arg=>value format will break if you load the integer.pm module. This is fixed in Perl 5.005_61 and up.

A workaround is to put all arguments in quotes: '-arg'=>'value'

You can't retrieve the name of the uploaded file using the param() method

When you accidentally try to upload a directory name, the browser hangs

You can read the name of the uploaded file, but can't retrieve the data

If you're on a non-Unix system you may need to modify CGI.pm to point at a suitable temporary directory. This directory must be writable by the user ID under which the server runs (usually "nobody") and must have sufficient capacity to handle large file uploads. Open up CGI.pm, and find the line:

      package TempFile;
      foreach ('/usr/tmp','/tmp') {
         do {$TMPDIRECTORY = $_; last} if -d $_ && -w _;
      }

Alternatively, you can just skip the search entirely and force CGI.pm to store its temporary files in some logical location. Do this at the top of your script with a line like this one: $TempFile::TMPDIRECTORY='/WWW_ROOT';

On Windows Systems, the temporary file is never deleted, but hangs around in \temp, taking up space.

Unix users don't have this problem, because well designed operating systems make it possible to delete a file without closing it.

When you press the "back" button, the same page is loaded, not the previous one.

A workaround for this is to use additional path information to trick Netscape into thinking that the form and the response have different URLs. I recommend giving each form a sequence number and bumping the sequence up by one each time the form is accessed:

   my($s) = $query->path_info=~/(\d+)/; # get sequence
   $s++;                                #bump it up
   # Trick Netscape into thinking it's loading a new script:
   print $q->start_multipart_form(-action=>$q->script_name . "/$s");

You can't find the temporary file that CGI.pm creates

Server Push

CGI.pm provides four simple functions for producing multipart documents of the type needed to implement server push. To import these into your namespace, you must import the ":push" set. You are also advised to put the script into NPH mode and to set $| to 1 to avoid buffering problems.

Here is a simple script that demonstrates server push:

#!/usr/local/bin/perl
use CGI qw/:push -nph/;
$| = 1;
print multipart_init(-boundary=>'----------------here we go!');
foreach (0 .. 4) {
   print multipart_start(-type=>'text/plain'),
         "The current time is ",scalar(localtime),"\n";
   if ($_ < 4) {
      print multipart_end;
   } else {
      print multipart_final;
   }
   sleep 1;
}

This script initializes server push by calling multipart_init(). It then enters a loop in which it begins a new multipart section by calling multipart_start(), prints the current local time, and ends a multipart section with multipart_end(). It then sleeps a second, and begins again. On the final iteration, it ends the multipart section with multipart_final() rather than with multipart_end().

multipart_init()

multipart_init(-boundary=>$boundary);
      

Initialize the multipart system. The -boundary argument specifies what MIME boundary string to use to separate parts of the document. If not provided, CGI.pm chooses a reasonable boundary for you.

multipart_start()

multipart_start(-type=>$type)
      

Start a new part of the multipart document using the specified MIME type. If not specified, text/html is assumed.

multipart_end()

  multipart_end()
      

End a part. You must remember to call multipart_end() once for each multipart_start(), except at the end of the last part of the multipart document when multipart_final() should be called instead of multipart_end().

multipart_final()

  multipart_final()
      

End all parts. You should call multipart_final() rather than multipart_end() at the end of the last part of the multipart document.

Only Netscape Navigator supports server push. Internet Explorer browsers do not.

Table of contents

Avoiding Denial of Service Attacks

Another possible attack is for the remote user to force CGI.pm to accept a huge file upload. CGI.pm will accept the upload and store it in a temporary directory even if your script doesn't expect to receive an uploaded file. CGI.pm will delete the file automatically when it terminates, but in the meantime the remote user may have filled up the server's disk space, causing problems for other programs.

The best way to avoid denial of service attacks is to limit the amount of memory, CPU time and disk space that CGI scripts can use. Some Web servers come with built-in facilities to accomplish this. In other cases, you can use the shell limit or ulimit commands to put ceilings on CGI resource usage.

CGI.pm also has some simple built-in protections against denial of service attacks, but you must activate them before you can use them. These take the form of two global variables in the CGI name space:

$CGI::POST_MAX

If set to a non-negative integer, this variable puts a ceiling on the size of POSTings, in bytes. If CGI.pm detects a POST that is greater than the ceiling, it will immediately exit with an error message. This value will affect both ordinary POSTs and multipart POSTs, meaning that it limits the maximum size of file uploads as well. You should set this to a reasonably high value, such as 1 megabyte.

$CGI::DISABLE_UPLOADS

If set to a non-zero value, this will disable file uploads completely. Other fill-out form values will work as usual.

1. On a script-by-script basis. Set the variable at the top of the script, right after the "use" statement:

         use CGI qw/:standard/;
         use CGI::Carp 'fatalsToBrowser';
         $CGI::POST_MAX=1024 * 100;  # max 100K posts
         $CGI::DISABLE_UPLOADS = 1;  # no uploads
         

2. Globally for all scripts. Open up CGI.pm, find the definitions for $POST_MAX and $DISABLE_UPLOADS, and set them to the desired values. You'll find them towards the top of the file in a subroutine named initialize_globals.

An attempt to send a POST larger than $POST_MAX bytes will cause param() to return an empty CGI parameter list. You can test for this event by checking cgi_error(), either after you create the CGI object or, if you are using the function-oriented interface, call param() for the first time. If the POST was intercepted, then cgi_error() will return the message "413 POST too large".

This error message is actually defined by the HTTP protocol, and is designed to be returned to the browser as the CGI script's status code. For example:

$uploaded_file = param('upload');
   if (!$uploaded_file && cgi_error()) {
      print header(-status=>cgi_error());
      exit 0;
   }

Some browsers may not know what to do with this status code. It may be better just to create an HTML page that warns the user of the problem. Table of contents

Using CGI.pm on non-Unix Platforms

There are a number of differences in file name and text processing conventions on different platforms. By default, CGI.pm is set up to work properly on a Unix (or Linux) system. During load, it will attempt to guess the correct operating system using the Config module. Currently it guesses correctly; however if the operating system names change it may not work right. The main symptom will be that file upload does not work correctly. If this happens, find the place at the top of the script where the OS is defined, and uncomment the correct definition:

   # CHANGE THIS VARIABLE FOR YOUR OPERATING SYSTEM
   # $OS = 'UNIX';
   # $OS = 'MACINTOSH';
   # $OS = 'WINDOWS';
   # $OS = 'VMS';

Windows NT

http://www.activestate.com/

WebSite uses a slightly different cgi-bin directory structure than the standard. For this server, place the scripts in the cgi-shl directory. CGI.pm appears to work correctly in both the Windows95 and WindowsNT versions of WebSite.

Old Netscape Communications Server technical notes recommended placing perl.exe in cgi-bin. This a very bad idea because it opens up a gaping security hole. Put a C .exe wrapper around the perl script until such time as Netscape recognizes NT file manager associations, or provides a Perl-compatible DLL library for its servers.

If you find that binary files get slightly larger when uploaded but that text files remain the same, then binary made is not correctly activated. Be sure to set the $OS variable to 'NT' or 'WINDOWS'. If you continue to have problems, make sure you're calling binmode() on the filehandle that you use to write the uploaded file to disk.

VMS

Macintosh

ftp://err.ethz.ch/pub/neeri/MacPerl/

1. The perl compiler will object to the use of -values in named parameters. Put single quotes around this parameter ('-values') or use the singular form ('-value') instead.
2. File upload isn't working in my hands (Perl goes into an endless loop). Other people have gotten it to work.

The Relation of this Library to the CGI Modules

The CGI::* modules are being reworked to be interoperable with the excellent LWP modules. Stay tuned.

The current version of CGI.pm can be found at:

  
http://www.genome.wi.mit.edu/ftp/pub/software/WWW/

You are encouraged to look at these other Web-related modules:

CGI::Base,CGI::Form,CGI::MiniSrv,CGI::Request and CGI::URI::URL

Modules for parsing script input, manipulating URLs, creating forms and even launching a miniature Web server.

libwww-perl

Modules for fetching Web resources from within Perl, writing Web robots, and much more.

GD.html

A module for creating GIF images on the fly, using Tom Boutell's gd graphics library.

qd.pl

A library for creating Macintosh PICT files on the fly (which can be converted to GIF or JPEG using NetPBM).

For a collection of CGI scripts of various levels of complexity, see the companion pages for my book How to Set Up and Maintain a World Wide Web Site

Distribution Information:

The CGI.pm Book

http://www.wiley.com/compbooks/stein/

CGI.pm and the Year 2000 Problem

The CGI-perl mailing list

Bug Reports

• the version of CGI.pm (perl -MCGI -e 'print $CGI::VERSION')
• the version of Perl (perl -v)
• the name and version of your Web server
• the name and version of the operating system you are using
• if applicable, the name and version of the browser you are using
• a short test script that reproduces the problem (30 lines or less)

Up to table of contents

Revision History

Version 3.05

1. Fixed uninitialized variable warning on start_form() when running from command line.
2. Fixed CGI::_set_attributes so that attributes with a - are handled correctly.
3. Fixed CGI::Carp::die() so as to avoid problems from _longmess() clobbering @_.
4. If HTTP_X_FORWARDED_HOST is defined (i.e. running under a proxy), the various functions that return HOST will use that instead.
5. Fix for undefined utf8() call in CGI::Util.
6. Changed the call to warningsToBrowser() in CGI::Carp::fatalsToBrowser to call only after HTTP header is sent (thanks to Didier Lebrun for noticing).
7. Patches from Dan Harkless to make CGI.pm validatable against HTML 3.2.
8. Fixed an extraneous "foo=bar" appearing when extra style parameters passed to start_html;
9. Fixed potential cross-site scripting bug in startform().
10. Fixed documentation to discuss list context behavior of form-element generators explicitly.
11. Fixed incorrect results from end_form() when called in OO manner.
12. Fixed query string stripping in order to handle URLs containing escaped newlines.
13. During server push, set NPH to 0 rather than 1. This is supposed to fix problems with Apache.
14. Fixed incorrect processing of multipart form fields that contain embedded quotes. There's still the issue of how to handle ones that contain embedded semicolons, but no one has complained (yet).
15. Fixed documentation bug in -style argument to start_html()
16. Added -status argument to redirect().

Version 3.04

1. Fixed the problem with mod_perl crashing when "defaults" button pressed.

Version 3.03

1. Fix upload hook functionality
2. Workaround for CGI->unescape_html()
3. Bumped version numbers in CGI::Fast and CGI::Util for 5.8.3-tobe

Version 3.02

1. Bring in Apache::Response just in case.
2. File upload on EBCDIC systems now works.

Version 3.01

1. No fix yet for upload failures when running on EBCDIC server.
2. Fixed uninitialized glob warnings that appeared when file uploading under perl 5.8.2.
3. Added patch from Schlomi Fish to allow debugging of PATH_INFO from command line.
4. Added patch from Steve Hay to correctly unlink tmp files under mod_perl/windows
5. Added upload_hook functionality from Jamie LeTaul
6. Workarounds for mod_perl 2 IO issues. Check that file upload and state saving still working.
7. Added code for underreads.
8. Fixed misleading description of redirect() and relative URLs in the POD docs.
9. Workaround for weird interaction of CGI::Carp with Safe module reported by William McKee.
10. Added patches from Ilmari Karonen to improve behavior of CGI::Carp.
11. Fixed documentation error in -style argument.
12. Added virtual_port() method for finding out what port server is listening on in a virtual-host aware fashion.

Version 3.00

1. Patch from Randal Schwartz to fix bug introduced by cross-site scripting vulnerability "fix."
2. Patch from JFreeman to replace UTF-8 escape constant of 0xfe with 0xfc. Hope this is right!

Version 2.99

1. Patch from Steve Hay to fix extra Content-type: appearing on browser screen when FatalsToBrowser invoked.
2. Patch from Ewann Corvellec to fix cross-site scripting vulnerability.
3. Fixed tmpdir routine for file uploading to solve problem that occurs under mod_perl when tmpdir is writable at startup time, but not at session time.

Version 2.98

1. Fixed crash in Dump() function.

Version 2.97

1. Sigh. Uploaded wrong 2.96 to CPAN.

Version 2.96

1. More bugfixes to the -style argument.

Version 2.95

1. Fixed bugs in start_html(-style=>...) support introduced in 2.94.

Version 2.94

1. Removed warning from reset() method.
2. Moved and
3. Changed CGI::Carp to play with mod_perl2 and to (hopefully) restore reporting of compile-time errors.
4. Fixed potential deadlock between web server and CGI.pm when aborting a read due to POST_MAX (reported by Antti Lankila).
5. Fixed issue with tag-generating function not incorporating content when first variable undef.
6. Fixed cross-site scripting bug reported by obscure.
7. Fixed Dump() function to return correctly formed XHTML - bug reported by Ralph Siemsen.

Version 2.93

1. Fixed embarassing bug in mp1 support.

Version 2.92

1. Fix to be P3P compliant submitted from MPREWITT.
2. Added CGI->r() API for mod_perl1/mod_perl2.
3. Fixed bug in redirect() that was corrupting cookies.
4. Minor fix to behavior of reset() button to make it consistent with submit() button (first time this has been changed in 9 years).
5. Patch from Dan Kogai to handle UTF-8 correctly in 5.8 and higher.
6. Patch from Steve Hay to make CGI::Carp's error messages appear on MSIE browsers.
7. Added Yair Lenga's patch for non-urlencoded postings.
8. Added Stas Bekman's patches for mod_perl 2 compatibility.
9. Fixed uninitialized escape behavior submitted by William Campbell.
10. Fixed tied behavior so that you can pass arguments to tie()
11. Fixed incorrect generation of URLs when the path_info contains + and other odd characters.
12. Fixed redirect(-cookies=>$cookie) problem.
13. Fixed tag generation bug that affects -javascript passed to start_html().

Version 2.91

1. Attribute generation now correctly respects the value of autoEscape().
2. Fixed endofrm() syntax error introduced by Ben Edgington's patch.

Version 2.90

1. Fixed bug in redirect header handling.
2. Added P3P option to header().
3. Patches from Alexey Mahotkin to make CGI::Carp work correctly with object-oriented exceptions.
4. Removed inaccurate description of how to set multiple cookies from CGI::Cookie pod file.
5. Patch from Kevin Mahony to prevent running out of filehandles when uploading lots of files.
6. Documentation enhancement from Mark Fisher to note that the import_names() method transforms the parameter names into valid Perl names.
7. Patch from Dan Harkless to suppress lang attribute in <html> tag if specified as a null string.
8. Patch from Ben Edgington to fix broken XHTML-transitional 1.0 validation on endform().
9. Custom html header fix from Steffen Beyer (first letter correctly upcased now)
10. Added a -verbatim option to stylesheet generation from Michael Dickson
11. Faster delete() method from Neelam Gupta
12. Fixed broken Cygwin support.
13. Added empty charset support from Bradley Baetz
14. Patches from Doug Perham and Kevin Mahoney to fix file upload failures when uploaded file is a multiple of 4096.

Version 2.89

1. Fixed behavior of ACTION tag when POSTING to a URL that has a query string.
2. Added Patch from Michael Rommel to handle multipart/mixed uploads from Opera

Version 2.88

1. Fixed problem with uploads being refused under Perl 5.8 when under Taint mode.
2. Fixed uninitialized variable warnings under Perl 5.8.
3. Fixed CGI::Pretty regression test failures.

Version 2.87

1. Security hole patched: when processing multipart/form-data postings, most arguments were being untainted silently. Returned arguments are now tainted correctly. This may cause some scripts to fail that used to work (thanks to Nick Cleaton for pointing this out and persisting until it was fixed).
2. Update for mod_perl 2.0.
3. Pragmas such as -no_xhtml are now respected in mod_perl environment.

Version 2.86

1. Fixes for broken CGI::Cookie expiration dates introduced in 2.84.

Version 2.85

1. Fix for broken autoEscape function introduced in 2.84.

Version 2.84

1. Fix for failed file uploads on Cygwin platforms.
2. HTML escaping code now replaced 0x8b and 0x9b with unicode references ‹ and *#8250;

Version 2.83

1. Fixed autoEscape() documentation inconsistencies.
2. Patch from Ville Skyttä to fix a number of XHTML inconsistencies.
3. Added Max-Age to list of CGI::Cookie headers.

Version 2.82

1. Patch from Rudolf Troller to add attribute setting and option groups to form fields.
2. Patch from Simon Perreault for silent crashes when using CGI::Carp under mod_perl.
3. Patch from Scott Gifford allows you to set the program name for CGI::Carp.

Version 2.81

1. Removed extraneous slash from end of stylesheet tags generated by start_html in non-XHTML mode.
2. Changed behavior of CGI::Carp with respect to eval{} contexts so that output behaves properly in mod_perl environments.
3. Fixed default DTD so that it validates with W3C validator.

Version 2.80

1. Fixed broken messages in CGI::Carp.
2. Changed checked="1" to checked="checked" for real XHTML compatibility.
3. Resurrected REQUEST_URI code so that url() works correctly with multiviews.

Version 2.79

1. Changes to CGI::Carp to avoid "subroutine redefined" error messages.
2. Default DTD is now XHTML 1.0 Transitional
3. Patches to support all HTML4 tags.

Version 2.78

1. Added ability to change encoding in <?xml> assertion.
2. Fixed the old escapeHTML('CGI') ne "CGI" bug
3. In accordance with XHTML requirements, there are no longer any minimized attributes, such as "checked".
4. Patched bug which caused file uploads of exactly 4096 bytes to be truncated to 4094 (thanks to Kevin Mahony)
5. New tests and fixes to CGI::Pretty (thanks to Michael Schwern).

Version 2.77

1. No new features, but released in order to fix an apparent CPAN bug.

Version 2.76

1. New esc.t regression test for EBCDIC translations courtesy Peter Prymmer.
2. Patches from James Jurach to make compatible with FCGI-ProcManager
3. Additional fields passed to header() (like -Content_disposition) now honor initial capitalization.
4. Patch from Andrew McNaughton to handle utf-8 escapes (%uXXXX codes) in URLs.

Version 2.752

1. Syntax error in the autoloaded Fh::new() subroutine.
2. Better error reporting in autoloaded functions.

Version 2.751

1. Tiny tweak to filename regular expression function on line 3355.

Version 2.75

1. Fixed bug in server push boundary strings (CGI.pm and CGI::Push).
2. Fixed bug that occurs when uploading files with funny characters in the name
3. Fixed non-XHTML-compliant attributes produced by textfield()
4. Added EPOC support, courtesy Olaf Flebbe
5. Fixed minor XHTML bugs.
6. Made escape() and unescape() symmetric with respect to EBCDIC, courtesy Roca, Ignasi <ignasi.roca@fujitsu.siemens.es>
7. Removed uninitialized variable warning from CGI::Cookie, provided by Atipat Rojnuckarin <rojnuca@yahoo.com>
8. Fixed bug in CGI::Pretty that causes it to print partial end tags when the $INDENT global is changed.
9. Single quotes are changed to character entity ' for compatibility with URLs.

Version 2.74

September 13, 2000

1. Quashed one-character bug that caused CGI.pm to fail on file uploads.

Version 2.73

September 12, 2000

1. Added -base to the list of arguments accepted by url().
2. Fixes to XHTML support.
3. POST parameters no longer show up in the Location box.

Version 2.72

August 19, 2000

1. Fixed the defaults button so that it works again
2. Charset is now correctly saved and restored when saving to files
3. url() now works correctly when given scripts with %20 and other escapes in the additional path info. This undoes a patch introduced in version 2.47 that I no longer understand the rationale for.

Version 2.71

August 13, 2000

1. Newlines in the value attributes of hidden fields and other form elements are now escaped when using ISO-Latin.
2. Inline script and style sections are now protected as CDATA sections when XHTML mode is on (the default).

Version 2.70

August 4, 2000

1. Fixed bug in scrolling_list() which omitted a space in front of the "multiple" attribute.
2. Squashed the "useless use of string in void context" message from redirects.

Version 2.69

1. startform() now creates default ACTION for POSTs as well as GETs. This may break some browsers, but it no longer violates the HTML spec.
2. CGI.pm now emits XHTML by default. Disable with -no_xhtml.
3. We no longer interpret &#ddd sequences in non-latin character sets.

Version 2.68

1. No longer attempts to escape characters when dealing with non ISO-8861 character sets.
2. checkbox() function now defaults to using -value as its label, rather than -name. The current behavior is what has been documented from the beginning.
3. -style accepts array reference to incorporate multiple stylesheets into document.

1. Fixed two bugs that caused the -compile pragma to fail with a syntax error.

Version 2.67

1. Added XHTML support (incomplete; tags need to be lowercased).
2. Fixed CGI/Carp when running under mod_perl. Probably broke in other contexts.
3. Fixed problems when passing multiple cookies.
4. Suppress warnings from _tableize() that were appearing when using -w switch with radio_group() and checkbox_group().
5. Support for the header() -attachment argument, which can give pages a default file name when saving to disk.

Version 2.66

1. 2.65 changes in make_attributes() broke HTTP header functions (including redirect), so made it context sensitive.

Version 2.65

1. Fixed regression tests to skip tests that require implicit fork on machines without fork().
2. Changed make_attributes() to automatically escape any HTML reserved characters.
3. Minor documentation fix in javascript example.

Version 2.64

1. Changes introduced in 2.63 broke param() when retrieving parameter lists containing only a single argument. This is now fixed.
2. self_url() now defaults to returning parameters delimited with semicolon. Use the pragma -oldstyle_urls to get the old "&" delimiter.

Version 2.63

1. Fixed CGI::Push to pull out parameters correctly.
2. Fixed redirect() so that it works with default character set
3. Changed param() so as to returned empty string '' when referring to variables passed in query strings like 'name1=&name2'

Version 2.62

1. Fixed broken ReadParse() function, and added regression tests
2. Fixed broken CGI::Pretty, and added regression tests

Version 2.61

1. Moved more functions from CGI.pm proper into CGI/Util.pm. CGI/Cookie should now be standalone.
2. Disabled per-user temporary directories, which were causing grief.

Version 2.60

1. Fixed junk appearing in autogenerated HTML functions when using object-oriented mode.

Version 2.59

1. autoescape functionality breaks too much existing code, removed it.
2. use escapeHTML() manually

Version 2.58

Version 2.57

1. Added -debug pragma and turned off auto reading of STDIN.
2. Default DTD updated to HTML 4.01 transitional.
3. Added charset() method and the -charset argument to header().
4. Fixed behavior of escapeHTML() to respect charset() and to escape nasty Windows characters (thanks to Tom Christiansen).
5. Handle REDIRECT_QUERY_STRING correctly.
6. Removed use_named_parameters() because of dependency problems and general lameness.
7. Fixed problems with bad HREF links generated by url(-relative=>1) when the url is like /people/.
8. Silenced a warning on upload (patch provided by Jonas Liljegren)
9. Fixed race condition in CGI::Carp when errors occur during parsing (patch provided by Maurice Aubrey).
10. Fixed failure of url(-path_info=>1) when path contains % signs.
11. Fixed warning from CGI::Cookie when receiving foreign cookies that don't use name=value format.
12. Fixed incompatibilities with file uploading on VMS systems.

Version 2.56

1. Fixed bugs in file upload introduced in version 2.55
2. Fixed long-standing bug that prevented two files with identical names from being uploaded.

Version 2.55

1. Fixed cookie regression test so as not to produce an error.
2. Fixed path_info() and self_url() to work correctly together when path_info() modified.
3. Removed manify warnings from CGI::{Switch,Apache}.

Version 2.54

1. This will be the last release of the monolithic CGI.pm module. Later versions will be modularized and optimized.
2. DOMAIN tag no longer added to cookies by default. This will break some versions of Internet Explorer, but will avoid breaking networks which use host tables without fully qualified domain names. For compatibility, please always add the -domain tag when creating cookies.
3. Fixed escape() method so that +'s are treated correctly.
4. Updated CGI::Pretty module.

Version 2.53

1. Forgot to upgrade regression tests before releasing 2.52. NOTHING ELSE HAS CHANGED IN LIBRARY

Version 2.52

1. Spurious newline in checkbox() routine removed. (courtesy John Essen)
2. TEXTAREA linebreaks now respected in dump() routine. (courtesy John Essen)
3. Patches for DOS ports (courtesy Robert Davies)
4. Patches for VMS
5. More fixes for cookie problems
6. Fix CGI::Carp so that it doesn't affect eval{} blocks (courtesy Byron Brummer)

Version 2.51

1. Fixed problems with cookies not being remembered when sent to IE 5.0 (and Netscape 5.0 too?)
2. Numerous HTML compliance problems in cgi_docs.html; fixed thanks to Michael Leahy

Version 2.50

1. Added a new Vars() method to retrieve all parameters as a tied hash.
2. Untainted tainted tempfile name so that script doesn't fail on terminal unlink.
3. Made picking of upload tempfile name more intelligent so that doesn't fail in case of name collision.
4. Fixed handling of expire times when passed an absolute timestamp.
5. Changed dump() to Dump() to avoid name clashes.

Version 2.49

1. Fixes for FastCGI (globals not getting reset)
2. Fixed url() to correctly handle query string and path under MOD_PERL

Version 2.48

1. Reverted detection of MOD_PERL to avoid breaking PerlEX.

Version 2.47

1. Patch to fix file upload bug appearing in IE 3.01 for Macintosh/PowerPC.
2. Replaced use of $ENV{SCRIPT_NAME} with $ENV{REQUEST_URI} when running under Apache, to fix self-referencing URIs.
3. Fixed bug in escapeHTML() which caused certain constructs, such as CGI->image_button(), to fail.
4. Fixed bug which caused strong('CGI') to fail. Be careful to use CGI::strong('CGI') and not CGI->strong('CGI'). The latter will produce confusing results.
5. Added upload() function, as a preferred replacement for the "filehandle as string" feature.
6. Added cgi_error() function.
7. Rewrote file upload handling to return undef rather than dieing when an error is encountered. Be sure to call cgi_error() to find out what went wrong.

Version 2.46

1. Fix for failure of the "include" tests under mod_perl
2. Added end_multipart_form to prevent failures during qw(-compile :all)

Version 2.45

1. Multiple small documentation fixes
2. CGI::Pretty didn't get into 2.44. Fixed now.

Version 2.44

1. Fixed file descriptor leak in upload function.
2. Fixed bug in header() that prevented fields from containing double quotes.
3. Added Brian Paulsen's CGI::Pretty package for pretty-printing output HTML.
4. Removed CGI::Apache and CGI::Switch from the distribution.
5. Generated start_* shortcuts so that start_table(), end_table(), start_ol(), end_ol(), and so forth now work (see the docs on how to enable this feature).
6. Changed accept() to Accept(), sub() to Sub(). There's still a conflict with reset(), but this will break too many existing scripts!

Version 2.43

1. Fixed problem with "use strict" and file uploads (thanks to Peter Haworth)
2. Fixed problem with not MSIE 3.01 for the power_mac not doing file uploads right.
3. Fixed problem with file upload on IIS 4.0 when authorization in use.
4. -content_type and '-content-type' can now be provided to header() as synonyms for -type.
5. CGI::Carp now escapes the ampersand BEFORE escaping the > and < signs.
6. Fixed "not an array reference" error when passing a hash reference to radio_group().
7. Fixed non-removal of uploaded TMP files on NT platforms which occurs when server runs on non-C drive (thanks to Steve Kilbane for finding this one).

Version 2.42

1. Too many screams of anguish at changed behavior of url(). Is now back to its old behavior by default, with options to generate all the variants.
2. Added regression tests. "make test" now works.
3. Documentation fixes.
4. Fixes for Macintosh uploads, but uploads STILL do not work pending changes to MacPerl.

Version 2.41

1. url() method now includes the path info. Use script_name() to get it without path info().
2. Changed handling of empty attributes in HTML tag generation. Be warned! Use table({-border=>undef}) rather than table({-border=>''}).
3. Changes to allow uploaded filenames to be compared to other strings with "eq", "cmp" and "ne".
4. Changes to allow CGI.pm to coexist more peacefully with ActiveState PerlEX.
5. Changes to prevent exported variables from clashing when importing ":all" set in combination with cookies.

Version 2.40

1. CGI::Carp patched to work better with mod_perl (thanks to Chris Dean).
2. Uploads of files whose names begin with numbers or the Windows \\UNC\shared\file nomenclature should no longer fail.
3. The <STYLE> tag (for cascading style sheets) now generates the required TYPE attribute.
4. Server push primitives added, thanks to Ed Jordan.
5. Table and other HTML3 functions are now part of the :standard set.
6. Small documentation fixes.

1. Do something about the DTD mess. The module should generate correct DTDs, or at least offer the programmer a way to specify the correct one.
2. Split CGI.pm into CGI processing and HTML-generating modules.
3. More robust file upload (?still not working on the Macintosh?).
4. Bring in all the HTML4 functionality, particular the accessibility features.

Version 2.39

1. file uploads failing because of VMS patch; fixed.
2. -dtd parameter was not being properly processed.

Version 2.38

Version 2.37, various beta versions

1. Added a CGI::Cookie::parse() method for lucky mod_perl users.
2. No longer need separate -values and -labels arguments for multi-valued form elements.
3. Added better interface to raw cookies (fix courtesy Ken Fox, kfox@ford.com)
4. Added param_fetch() function for direct access to parameter list.
5. Fix to checkbox() to allow for multi-valued single checkboxes (weird problem).
6. Added a compile() method for those who want to compile without importing.
7. Documented the import pragmas a little better.
8. Added a -compile switch to the use clause for the long-suffering mod_perl and Perl compiler users.
9. Fixed initialization routines so that FileHandle and type globs work correctly (and hash initialization doesn't fail!).
10. Better deletion of temporary files on NT systems.
11. Added documentation on escape(), unescape(), unescapeHTML() and unescapeHTML() subroutines.
12. Added documentation on creating subclasses.
13. Fixed problem when calling $self->SUPER::foo() from inheriting subclasses.
14. Fixed problem using filehandles from within subroutines.
15. Fixed inability to use the string "CGI" as a parameter.
16. Fixed exponentially growing $FILLUNIT bug
17. Check for undef filehandle in read_from_client()
18. Now requires the UNIVERSAL.pm module, present in Perl 5.003_7 or higher.
19. Fixed problem with uppercase-only parameters being ignored.
20. Fixed vanishing cookie problem.
21. Fixed warning in initialize_globals() under mod_perl.
22. File uploads from Macintosh versions of MSIE should now work.
23. Pragmas now preceded by dashes (-nph) rather than colons (:nph). Old style is supported for backward compatability.
24. Can now pass arguments to all functions using {} brackets, resolving historical inconsistencies.
25. Removed autoloader warnings about absent MultipartBuffer::DESTROY.
26. Fixed non-sticky checkbox() when -name used without -value.
27. Hack to fix path_info() in IIS 2.0. Doesn't help with IIS 3.0.
28. Parameter syntax for debugging from command line now more straightforward.
29. Added $DISABLE_UPLOAD to disable file uploads.
30. Added $POST_MAX to error out if POSTings exceed some ceiling.
31. Fixed url_param(), which wasn't working at all.
32. Fixed variable suicide problem in s///e expressions, where the autoloader was needed during evaluation.
33. Removed excess spaces between elements of checkbox and radio groups
34. Can now create "valueless" submit buttons
35. Can now set path_info as well as read it.
36. ReadParse() now returns a useful function result.
37. import_names() now allows you to optionally clear out the namespace before importing (for mod_perl users)
38. Made it possible to have a popup menu or radio button with a value of "0".
39. link() changed to Link() to avoid overriding native link function.
40. Takes advantage of mod_perl's register_cleanup() function to clear globals.
41. <LAYER> and <ILAYER> added to :html3 functions.
42. Fixed problems with private tempfiles and NT/IIS systems.
43. No longer prints the DTD by default (I bet no one will complain).
44. Allow underscores to replace internal hyphens in parameter names.
45. CGI::Push supports heterogeneous MIME types and adjustable delays between pages.
46. url_param() method added for retrieving URL parameters even when a fill-out form is POSTed.
47. Got rid of warnings when radio_group() is called.
48. Cookies now moved to their very own module.
49. Fixed documentation bug in CGI::Fast.
50. Added a :no_debug pragma to the import list.

Version 2.36

1. Expanded JavaScript functionality
2. Preliminary support for cascading stylesheets
3. Security fixes for file uploads:
   • Module will bail out if its temporary file already exists
   • Temporary files can now be made completely private to avoid peeking by other users or CGI scripts.
4. use CGI qw/:nph/ wasn't working correctly. Now it is.
5. Cookie and HTTP date formats didn't meet spec. Thanks to Mark Fisher (fisherm@indy.tce.com) for catching and fixing this.

Version 2.35

1. Robustified multipart file upload against incorrect syntax in POST.
2. Fixed more problems with mod_perl.
3. Added -noScript parameter to start_html().
4. Documentation fixes.

Version 2.34

1. Stupid typo fix

Version 2.33

1. Fixed a warning about an undefined environment variable.
2. Doug's patch for redirect() under mod_perl
3. Partial fix for busted inheritence from CGI::Apache
4. Documentation fixes.

Version 2.32

1. Improved support for Apache's mod_perl.
2. Changes to better support inheritance.
3. Support for OS/2.

Version 2.31

1. New uploadInfo() method to obtain header information from uploaded files.
2. cookie() without any arguments returns all the cookies passed to a script.
3. Removed annoying warnings about $ENV{NPH} when running with the -w switch.
4. Removed operator overloading throughout to make compatible with new versions of perl.
5. -expires now implies the -date header, to avoid clock skew.
6. WebSite passes cookies in $ENV{COOKIE} rather than $ENV{HTTP_COOKIE}. We now handle this, even though it's O'Reilly's fault.
7. Tested successfully against new sfio I/O layer.
8. Documentation fixes.

Version 2.30

1. Automatic detection of operating system at load time.
2. Changed select() function to Select() in order to avoid conflict with Perl built-in.
3. Added Tr() as an alternative to TR(); some people think it looks better that way.
4. Fixed problem with autoloading of MultipartBuffer::DESTROY code.
5. Added the following methods:
   • virtual_host()
   • server_software()
6. Automatic NPH mode when running under Microsoft IIS server.

Version 2.29

1. Fixed cookie bugs
2. Fixed problems that cropped up when useNamedParameters was set to 1.
3. Prevent CGI::Carp::fatalsToBrowser() from crapping out when encountering a die() within an eval().
4. Fixed problems with filehandle initializers.

Version 2.28

1. Added support for NPH scripts; also fixes problems with Microsoft IIS.
2. Fixed a problem with checkbox() values not being correctly saved and restored.
3. Fixed a bug in which CGI objects created with empty string initializers took on default values from earlier CGI objects.
4. Documentation fixes.

Version 2.27

1. Small but important bug fix: the automatic capitalization of tag attributes was accidentally capitalizing the VALUES as well as the ATTRIBUTE names (oops).

Version 2.26

1. Changed behavior of scrolling_list(), checkbox() and checkbox_group() methods so that defaults are honored correctly. The "fix" causes endform() to generate additional <INPUT TYPE="HIDDEN"> tags -- don't be surpised.
2. Fixed bug involving the detection of the SSL protocol.
3. Fixed documentation error in position of the -meta argument in start_html().
4. HTML shortcuts now generate tags in ALL UPPERCASE.
5. start_html() now generates correct SGML header:

         <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
         

6. CGI::Carp no longer fails "use strict refs" pragma.

Version 2.25

1. Fixed bug that caused bad redirection on destination URLs with arguments.
2. Fixed bug involving use_named_parameters() followed by start_multipart_form()
3. Fixed bug that caused incorrect determination of binmode for Macintosh.
4. Spelling fixes on documentation.

Version 2.24

1. Fixed bug that caused generation of lousy HTML for some form elements
2. Fixed uploading bug in Windows NT
3. Some code cleanup (not enough)

Version 2.23

1. Fixed an obscure bug that caused scripts to fail mysteriously.
2. Fixed auto-caching bug.
3. Fixed bug that prevented HTML shortcuts from passing taint checks.
4. Fixed some -w warning problems.

Version 2.22

1. New CGI::Fast module for use with FastCGI protocol. See pod documentation for details.
2. Fixed problems with inheritance and autoloading.
3. Added TR() (<tr>) and PARAM() (<param>) methods to list of exported HTML tag-generating functions.
4. Moved all CGI-related I/O to a bottleneck method so that this can be overridden more easily in mod_perl (thanks to Doug MacEachern).
5. put() method as substitute for print() for use in mod_perl.
6. Fixed crash in tmpFileName() method.
7. Added tmpFileName(), startform() and endform() to export list.
8. Fixed problems with attributes in HTML shortcuts.
9. Functions that don't actually need access to the CGI object now no longer generate a default one. May speed things up slightly.
10. Aesthetic improvements in generated HTML.
11. New examples.

Version 2.21

1. Added the -meta argument to start_html().
2. Fixed hidden fields (again).
3. Radio_group() and checkbox_group() now return an appropriate scalar value when called in a scalar context, rather than returning a numeric value!
4. Cleaned up the formatting of form elements to avoid unesthetic extra spaces within the attributes.
5. HTML elements now correctly include the closing tag when parameters are present but null: em('')
6. Added password_field() to the export list.

Version 2.20

1. Dumped the SelfLoader because of problems with running with taint checks and rolled my own. Performance is now significantly improved.
2. Added HTML shortcuts.
3. import() now adheres to the Perl module conventions, allowing CGI.pm to import any or all method names into the user's name space.
4. Added the ability to initialize CGI objects from strings and associative arrays.
5. Made it possible to initialize CGI objects with filehandle references rather than filehandle strings.
6. Added the delete_all() and append() methods.
7. CGI objects correctly initialize from filehandles on NT/95 systems now.
8. Fixed the problem with binary file uploads on NT/95 systems.
9. Fixed bug in redirect().
10. Added '-Window-target' parameter to redirect().
11. Fixed import_names() so that parameter names containing funny characters work.
12. Broke the unfortunate connection between cookie and CGI parameter name space.
13. Fixed problems with hidden fields whose values are 0.
14. Cleaned up the documentation somewhat.

Version 2.19

1. Added cookie() support routines.
2. Added -expires parameter to header().
3. Added cgi-lib.pl compatability mode.
4. Made the module more configurable for different operating systems.
5. Fixed a dumb bug in JavaScript button() method.

Version 2.18

1. Fixed a bug that corrects a hang that occurs on some platforms when processing file uploads. Unfortunately this disables the check for bad Netscape uploads.
2. Fixed bizarre problem involving the inability to process uploaded files that begin with a non alphabetic character in the file name.
3. Fixed a bug in the hidden fields involving the -override directive being ignored when scalar defaults were passed.
4. Added documentation on how to disable the SelfLoader features.

Version 2.17

1. Added support for the SelfLoader module.
2. Added oodles of JavaScript support routines.
3. Fixed bad bug in query_string() method that caused some parameters to be silently dropped.
4. Robustified file upload code to handle premature termination by the client.
5. Exported temporary file names on file upload.
6. Removed spurious "uninitialized variable" warnings that appeared when running under 5.002.
7. Added the Carp.pm library to the standard distribution.
8. Fixed a number of errors in this documentation, and probably added a few more.
9. Checkbox_group() and radio_group() now return the buttons as arrays, so that you can incorporate the individual buttons into specialized tables.
10. Added the '-nolabels' option to checkbox_group() and radio_group(). Probably should be added to all the other HTML-generating routines.
11. Added the url() method to recover the URL without the entire query string appended.
12. Added request_method() to list of environment variables available.
13. Would you believe it? Fixed hidden fields again!

Version 2.16

1. Fixed hidden fields yet again.
2. Fixed subtle problems in the file upload method that caused intermittent failures (thanks to Keven Hendrick for this one).
3. Made file upload more robust in the face of bizarre behavior by the Macintosh and Windows Netscape clients.
4. Moved the POD documentation to the bottom of the module at the request of Stephen Dahmen.
5. Added the -xbase parameter to the start_html() method, also at the request of Stephen Dahmen.
6. Added JavaScript form buttons at Stephen's request. I'm not sure how to use this Netscape extension correctly, however, so for now the form() method is in the module as an undocumented feature. Use at your own risk!

Version 2.15

1. Added the -override parameter to all field-generating methods.
2. Documented the user_name() and remote_user() methods.
3. Fixed bugs that prevented empty strings from being recognized as valid textfield contents.
4. Documented the use of framesets and added a frameset example.

Version 2.14

Version 2.13

1. Fixed a bug that interfered with the value "0" being entered into text fields.

Version 2.01

1. Added -rows and -columns to the radio and checkbox groups. No doubt this will cause much grief because it seems to promise a level of meta-organization that it doesn't actually provide.
2. Fixed a bug in the redirect() method -- it was not truly HTTP/1.0 compliant.

Version 2.0

1. Support for named parameter style method calls. This turns out to be a big win for extending CGI.pm when Netscape adds new HTML "features".
2. Changed behavior of hidden fields back to the correct "sticky" behavior. This is going to break some programs, but it is for the best in the long run.
3. Netscape 2.0b2 broke the file upload feature. CGI.pm now handles both 2.0b1 and 2.0b2-style uploading. It will probably break again in 2.0b3.
4. There were still problems with library being unable to distinguish between a form being loaded for the first time, and a subsequent loading with all fields blank. We now forcibly create a default name for the Submit button (if not provided) so that there's always at least one parameter.
5. More workarounds to prevent annoying spurious warning messages when run under the -w switch. -w is seriously broken in perl 5.001!

Version 1.57

1. Support for the Netscape 2.0 "File upload" field.
2. The handling of defaults for selected items in scrolling lists and multiple checkboxes is now consistent.

Version 1.56

1. Created true "pod" documentation for the module.
2. Cleaned up the code to avoid many of the spurious "use of uninitialized variable" warnings when running with the -w switch.
3. Added the autoEscape() method. v
4. Added string interpolation of the CGI object.
5. Added the ability to pass additional parameters to the <BODY> tag.
6. Added the ability to specify the status code in the HTTP header.

Bug fixes in version 1.55

1. Every time self_url() was called, the parameter list would grow. This was a bad "feature".
2. Documented the fact that you can pass "-" to radio_group() in order to prevent any button from being highlighted by default.

Bug fixes in version 1.54

1. The user_agent() method is now documented;
2. A potential security hole in import() is now plugged.
3. Changed name of import() to import_names() for compatability with CGI:: modules.

Bug fixes in version 1.53

1. Fixed several typos in the code that were causing the following subroutines to fail in some circumstances
   1. checkbox()
   2. hidden()
2. No features added

New features added in version 1.52

1. Added backslashing, quotation marks, and other shell-style escape sequences to the parameters passed in during debugging off-line.
2. Changed the way that the hidden() method works so that the default value always overrides the current one.
3. Improved the handling of sticky values in forms. It's now less likely that sticky values will get stuck.
4. If you call server_name(), script_name() and several other methods when running offline, the methods now create "dummy" values to work with.

Bugs fixed in version 1.51

1. param() when called without arguments was returning an array of length 1 even when there were no parameters to be had. Bad bug! Bad!
2. The HTML code generated would break if input fields contained the forbidden characters ">< or &. You can now use these characters freely.

New features added in version 1.50

1. import() method allows all the parameters to be imported into a namespace in one fell swoop.
2. Parameters are now returned in the same order in which they were defined.

Bugs fixed in version 1.45

1. delete() method didn't work correctly. This is now fixed.
2. reset() method didn't allow you to set the name of the button. Fixed.

Bugs fixed in version 1.44

1. self_url() didn't include the path information. This is now fixed.

New features added in version 1.43

1. Added the delete() method.

New features added in version 1.42

1. The image_button() method to create clickable images.
2. A few bug fixes involving forms embedded in <PRE> blocks.

New features added in version 1.4

1. New header shortcut methods
   • redirect() to create HTTP redirection messages.
   • start_html() to create the HTML title, complete with the recommended <LINK> tag that no one ever remembers to include.
   • end_html() for completeness' sake.
2. A new save() method that allows you to write out the state of an script to a file or pipe.
3. An improved version of the new() method that allows you to restore the state of a script from a file or pipe. With (2) this gives you dump and restore capabilities! (Wow, you can put a "121,931 customers served" banner at the bottom of your pages!)
4. A self_url() method that allows you to create state-maintaining hypertext links. In addition to allowing you to maintain the state of your scripts between invocations, this lets you work around a problem that some browsers have when jumping to internal links in a document that contains a form -- the form information gets lost.
5. The user-visible labels in checkboxes, radio buttons, popup menus and scrolling lists have now been decoupled from the values sent to your CGI script. Your script can know a checkbox by the name of "cb1" while the user knows it by a more descriptive name. I've also added some parameters that were missing from the text fields, such as MAXLENGTH.
6. A whole bunch of methods have been added to get at environment variables involved in user verification and other obscure features.

Bug fixes

1. The problems with the hidden fields have (I hope at last) been fixed.
2. You can create multiple query objects and they will all be initialized correctly. This simplifies the creation of multiple forms on one page.
3. The URL unescaping code works correctly now.