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HTML::Form(3)                        User Contributed Perl Documentation                       HTML::Form(3)



NAME
       HTML::Form - Class that represents an HTML form element

SYNOPSIS
        use HTML::Form;
        $form = HTML::Form->parse($html, $base_uri);
        $form->value(query => "Perl");

        use LWP::UserAgent;
        $ua = LWP::UserAgent->new;
        $response = $ua->request($form->click);

DESCRIPTION
       Objects of the "HTML::Form" class represents a single HTML "<form> ... </form>" instance.  A form
       consists of a sequence of inputs that usually have names, and which can take on various values.  The
       state of a form can be tweaked and it can then be asked to provide "HTTP::Request" objects that can
       be passed to the request() method of "LWP::UserAgent".

       The following methods are available:

       @forms = HTML::Form->parse( $html_document, $base_uri )
       @forms = HTML::Form->parse( $html_document, base => $base_uri, %opt )
       @forms = HTML::Form->parse( $response, %opt )
           The parse() class method will parse an HTML document and build up "HTML::Form" objects for each
           <form> element found.  If called in scalar context only returns the first <form>.  Returns an
           empty list if there are no forms to be found.

           The required arguments is the HTML document to parse ($html_document) and the URI used to
           retrieve the document ($base_uri).  The base URI is needed to resolve relative action URIs.  The
           provided HTML document should be a Unicode string (or US-ASCII).

           By default HTML::Form assumes that the original document was UTF-8 encoded and thus encode forms
           that don't specify an explicit accept-charset as UTF-8.  The charset assumed can be overridden by
           providing the "charset" option to parse().  It's a good idea to be explicit about this parameter
           as well, thus the recommended simplest invocation becomes:

               my @forms = HTML::Form->parse(
                   Encode::decode($encoding, $html_document_bytes),
                   base => $base_uri,
                   charset => $encoding,
               );

           If the document was retrieved with LWP then the response object provide methods to obtain a
           proper value for "base" and "charset":

               my $ua = LWP::UserAgent->new;
               my $response = $ua->get("http://www.example.com/form.html");
               my @forms = HTML::Form->parse($response->decoded_content,
                   base => $response->base,
                   charset => $response->content_charset,
               );

           In fact, the parse() method can parse from an "HTTP::Response" object directly, so the example
           above can be more conveniently written as:

               my $ua = LWP::UserAgent->new;
               my $response = $ua->get("http://www.example.com/form.html");
               my @forms = HTML::Form->parse($response);

           Note that any object that implements a decoded_content(), base() and content_charset() method
           with similar behaviour as "HTTP::Response" will do.

           Additional options might be passed in to control how the parse method behaves.  The following are
           all the options currently recognized:

           "base => $uri"
               This is the URI used to retrive the original document.  This option is not optional ;-)

           "charset => $str"
               Specify what charset the original document was encoded in.  This is used as the default for
               accept_charset.  If not provided this defaults to "UTF-8".

           "verbose => $bool"
               Warn (print messages to STDERR) about any bad HTML form constructs found.  You can trap these
               with $SIG{__WARN__}.  The default is not to issue warnings.

           "strict => $bool"
               Initialize any form objects with the given strict attribute.  If the strict is turned on the
               methods that change values of the form will croak if you try to set illegal values or modify
               readonly fields.  The default is not to be strict.

       $method = $form->method
       $form->method( $new_method )
           This method is gets/sets the method name used for the "HTTP::Request" generated.  It is a string
           like "GET" or "POST".

       $action = $form->action
       $form->action( $new_action )
           This method gets/sets the URI which we want to apply the request method to.

       $enctype = $form->enctype
       $form->enctype( $new_enctype )
           This method gets/sets the encoding type for the form data.  It is a string like
           "application/x-www-form-urlencoded" or "multipart/form-data".

       $accept = $form->accept_charset
       $form->accept_charset( $new_accept )
           This method gets/sets the list of charset encodings that the server processing the form accepts.
           Current implementation supports only one-element lists.  Default value is "UNKNOWN" which we
           interpret as a request to use document charset as specified by the 'charset' parameter of the
           parse() method.

       $value = $form->attr( $name )
       $form->attr( $name, $new_value )
           This method give access to the original HTML attributes of the <form> tag.  The $name should
           always be passed in lower case.

           Example:

              @f = HTML::Form->parse( $html, $foo );
              @f = grep $_->attr("id") eq "foo", @f;
              die "No form named 'foo' found" unless @f;
              $foo = shift @f;

       $bool = $form->strict
       $form->strict( $bool )
           Gets/sets the strict attribute of a form.  If the strict is turned on the methods that change
           values of the form will croak if you try to set illegal values or modify readonly fields.  The
           default is not to be strict.

       @inputs = $form->inputs
           This method returns the list of inputs in the form.  If called in scalar context it returns the
           number of inputs contained in the form.  See "INPUTS" for what methods are available for the
           input objects returned.

       $input = $form->find_input( $selector )
       $input = $form->find_input( $selector, $type )
       $input = $form->find_input( $selector, $type, $index )
           This method is used to locate specific inputs within the form.  All inputs that match the
           arguments given are returned.  In scalar context only the first is returned, or "undef" if none
           match.

           If $selector is specified, then the input's name, id, class attribute must match.  A selector
           prefixed with '#' must match the id attribute of the input.  A selector prefixed with '.' matches
           the class attribute.  A selector prefixed with '^' or with no prefix matches the name attribute.

           If $type is specified, then the input must have the specified type.  The following type names are
           used: "text", "password", "hidden", "textarea", "file", "image", "submit", "radio", "checkbox"
           and "option".

           The $index is the sequence number of the input matched where 1 is the first.  If combined with
           $name and/or $type then it select the nth input with the given name and/or type.

       $value = $form->value( $selector )
       $form->value( $selector, $new_value )
           The value() method can be used to get/set the value of some input.  If strict is enabled and no
           input has the indicated name, then this method will croak.

           If multiple inputs have the same name, only the first one will be affected.

           The call:

               $form->value('foo')

           is basically a short-hand for:

               $form->find_input('foo')->value;

       @names = $form->param
       @values = $form->param( $name )
       $form->param( $name, $value, ... )
       $form->param( $name, \@values )
           Alternative interface to examining and setting the values of the form.

           If called without arguments then it returns the names of all the inputs in the form.  The names
           will not repeat even if multiple inputs have the same name.  In scalar context the number of
           different names is returned.

           If called with a single argument then it returns the value or values of inputs with the given
           name.  If called in scalar context only the first value is returned.  If no input exists with the
           given name, then "undef" is returned.

           If called with 2 or more arguments then it will set values of the named inputs.  This form will
           croak if no inputs have the given name or if any of the values provided does not fit.  Values can
           also be provided as a reference to an array.  This form will allow unsetting all values with the
           given name as well.

           This interface resembles that of the param() function of the CGI module.

       $form->try_others( \&callback )
           This method will iterate over all permutations of unvisited enumerated values (<select>, <radio>,
           <checkbox>) and invoke the callback for each.  The callback is passed the $form as argument.  The
           return value from the callback is ignored and the try_others() method itself does not return
           anything.

       $request = $form->make_request
           Will return an "HTTP::Request" object that reflects the current setting of the form.  You might
           want to use the click() method instead.

       $request = $form->click
       $request = $form->click( $selector )
       $request = $form->click( $x, $y )
       $request = $form->click( $selector, $x, $y )
           Will "click" on the first clickable input (which will be of type "submit" or "image").  The
           result of clicking is an "HTTP::Request" object that can then be passed to "LWP::UserAgent" if
           you want to obtain the server response.

           If a $selector is specified, we will click on the first clickable input matching the selector,
           and the method will croak if no matching clickable input is found.  If $selector is not
           specified, then it is ok if the form contains no clickable inputs.  In this case the click()
           method returns the same request as the make_request() method would do.  See description of the
           find_input() method above for how the $selector is specified.

           If there are multiple clickable inputs with the same name, then there is no way to get the
           click() method of the "HTML::Form" to click on any but the first.  If you need this you would
           have to locate the input with find_input() and invoke the click() method on the given input
           yourself.

           A click coordinate pair can also be provided, but this only makes a difference if you clicked on
           an image.  The default coordinate is (1,1).  The upper-left corner of the image is (0,0), but
           some badly coded CGI scripts are known to not recognize this.  Therefore (1,1) was selected as a
           safer default.

       @kw = $form->form
           Returns the current setting as a sequence of key/value pairs.  Note that keys might be repeated,
           which means that some values might be lost if the return values are assigned to a hash.

           In scalar context this method returns the number of key/value pairs generated.

       $form->dump
           Returns a textual representation of current state of the form.  Mainly useful for debugging.  If
           called in void context, then the dump is printed on STDERR.

INPUTS
       An "HTML::Form" objects contains a sequence of inputs.  References to the inputs can be obtained with
       the $form->inputs or $form->find_input methods.

       Note that there is not a one-to-one correspondence between input objects and <input> elements in the
       HTML document.  An input object basically represents a name/value pair, so when multiple HTML
       elements contribute to the same name/value pair in the submitted form they are combined.

       The input elements that are mapped one-to-one are "text", "textarea", "password", "hidden", "file",
       "image", "submit" and "checkbox".  For the "radio" and "option" inputs the story is not as simple:
       All <input type="radio"> elements with the same name will contribute to the same input radio object.
       The number of radio input objects will be the same as the number of distinct names used for the
       <input type="radio"> elements.  For a <select> element without the "multiple" attribute there will be
       one input object of type of "option".  For a <select multiple> element there will be one input object
       for each contained <option> element.  Each one of these option objects will have the same name.

       The following methods are available for the input objects:

       $input->type
           Returns the type of this input.  The type is one of the following strings: "text", "password",
           "hidden", "textarea", "file", "image", "submit", "radio", "checkbox" or "option".

       $name = $input->name
       $input->name( $new_name )
           This method can be used to get/set the current name of the input.

       $input->id
       $input->class
           These methods can be used to get/set the current id or class attribute for the input.

       $input->selected( $selector )
           Returns TRUE if the given selector matched the input.  See the description of the find_input()
           method above for a description of the selector syntax.

       $value = $input->value
       $input->value( $new_value )
           This method can be used to get/set the current value of an input.

           If strict is enabled and the input only can take an enumerated list of values, then it is an
           error to try to set it to something else and the method will croak if you try.

           You will also be able to set the value of read-only inputs, but a warning will be generated if
           running under "perl -w".

       $input->possible_values
           Returns a list of all values that an input can take.  For inputs that do not have discrete
           values, this returns an empty list.

       $input->other_possible_values
           Returns a list of all values not tried yet.

       $input->value_names
           For some inputs the values can have names that are different from the values themselves.  The
           number of names returned by this method will match the number of values reported by
           $input->possible_values.

           When setting values using the value() method it is also possible to use the value names in place
           of the value itself.

       $bool = $input->readonly
       $input->readonly( $bool )
           This method is used to get/set the value of the readonly attribute.  You are allowed to modify
           the value of readonly inputs, but setting the value will generate some noise when warnings are
           enabled.  Hidden fields always start out readonly.

       $bool = $input->disabled
       $input->disabled( $bool )
           This method is used to get/set the value of the disabled attribute.  Disabled inputs do not
           contribute any key/value pairs for the form value.

       $input->form_name_value
           Returns a (possible empty) list of key/value pairs that should be incorporated in the form value
           from this input.

       $input->check
           Some input types represent toggles that can be turned on/off.  This includes "checkbox" and
           "option" inputs.  Calling this method turns this input on without having to know the value name.
           If the input is already on, then nothing happens.

           This has the same effect as:

               $input->value($input->possible_values[1]);

           The input can be turned off with:

               $input->value(undef);

       $input->click($form, $x, $y)
           Some input types (currently "submit" buttons and "images") can be clicked to submit the form.
           The click() method returns the corresponding "HTTP::Request" object.

       If the input is of type "file", then it has these additional methods:

       $input->file
           This is just an alias for the value() method.  It sets the filename to read data from.

           For security reasons this field will never be initialized from the parsing of a form.  This
           prevents the server from triggering stealth uploads of arbitrary files from the client machine.

       $filename = $input->filename
       $input->filename( $new_filename )
           This get/sets the filename reported to the server during file upload.  This attribute defaults to
           the value reported by the file() method.

       $content = $input->content
       $input->content( $new_content )
           This get/sets the file content provided to the server during file upload.  This method can be
           used if you do not want the content to be read from an actual file.

       @headers = $input->headers
       input->headers($key => $value, .... )
           This get/set additional header fields describing the file uploaded.  This can for instance be
           used to set the "Content-Type" reported for the file.

SEE ALSO
       LWP, LWP::UserAgent, HTML::Parser

COPYRIGHT
       Copyright 1998-2008 Gisle Aas.

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.



perl v5.16.2                                     2012-03-30                                    HTML::Form(3)