1HTML::Form(3)         User Contributed Perl Documentation        HTML::Form(3)
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3
4

NAME

6       HTML::Form - Class that represents an HTML form element
7

VERSION

9       version 6.07
10

SYNOPSIS

12        use HTML::Form;
13        $form = HTML::Form->parse($html, $base_uri);
14        $form->value(query => "Perl");
15
16        use LWP::UserAgent;
17        $ua = LWP::UserAgent->new;
18        $response = $ua->request($form->click);
19

DESCRIPTION

21       Objects of the "HTML::Form" class represents a single HTML "<form> ...
22       </form>" instance.  A form consists of a sequence of inputs that
23       usually have names, and which can take on various values.  The state of
24       a form can be tweaked and it can then be asked to provide HTTP::Request
25       objects that can be passed to the request() method of LWP::UserAgent.
26
27       The following methods are available:
28
29       @forms = HTML::Form->parse( $html_document, $base_uri )
30       @forms = HTML::Form->parse( $html_document, base => $base_uri, %opt )
31       @forms = HTML::Form->parse( $response, %opt )
32           The parse() class method will parse an HTML document and build up
33           "HTML::Form" objects for each <form> element found.  If called in
34           scalar context only returns the first <form>.  Returns an empty
35           list if there are no forms to be found.
36
37           The required arguments is the HTML document to parse
38           ($html_document) and the URI used to retrieve the document
39           ($base_uri).  The base URI is needed to resolve relative action
40           URIs.  The provided HTML document should be a Unicode string (or
41           US-ASCII).
42
43           By default HTML::Form assumes that the original document was UTF-8
44           encoded and thus encode forms that don't specify an explicit
45           accept-charset as UTF-8.  The charset assumed can be overridden by
46           providing the "charset" option to parse().  It's a good idea to be
47           explicit about this parameter as well, thus the recommended
48           simplest invocation becomes:
49
50               my @forms = HTML::Form->parse(
51                   Encode::decode($encoding, $html_document_bytes),
52                   base => $base_uri,
53                   charset => $encoding,
54               );
55
56           If the document was retrieved with LWP then the response object
57           provide methods to obtain a proper value for "base" and "charset":
58
59               my $ua = LWP::UserAgent->new;
60               my $response = $ua->get("http://www.example.com/form.html");
61               my @forms = HTML::Form->parse($response->decoded_content,
62                   base => $response->base,
63                   charset => $response->content_charset,
64               );
65
66           In fact, the parse() method can parse from an HTTP::Response object
67           directly, so the example above can be more conveniently written as:
68
69               my $ua = LWP::UserAgent->new;
70               my $response = $ua->get("http://www.example.com/form.html");
71               my @forms = HTML::Form->parse($response);
72
73           Note that any object that implements a decoded_content(), base()
74           and content_charset() method with similar behaviour as
75           HTTP::Response will do.
76
77           Additional options might be passed in to control how the parse
78           method behaves.  The following are all the options currently
79           recognized:
80
81           "base => $uri"
82               This is the URI used to retrieve the original document.  This
83               option is not optional ;-)
84
85           "charset => $str"
86               Specify what charset the original document was encoded in.
87               This is used as the default for accept_charset.  If not
88               provided this defaults to "UTF-8".
89
90           "verbose => $bool"
91               Warn (print messages to STDERR) about any bad HTML form
92               constructs found.  You can trap these with $SIG{__WARN__}.  The
93               default is not to issue warnings.
94
95           "strict => $bool"
96               Initialize any form objects with the given strict attribute.
97               If the strict is turned on the methods that change values of
98               the form will croak if you try to set illegal values or modify
99               readonly fields.  The default is not to be strict.
100
101       $form->push_input( $type, \%attr, $verbose )
102           This method adds additional inputs to the form.  The first argument
103           is the type of input (e.g. hidden, option, etc.).  The second
104           argument is a reference to a hash of the input attributes.  The
105           third argument is optional, and will issue warnings about unknown
106           input types.
107
108           Example:
109
110               push_input( 'hidden', {
111                   name  => 'NewFormElement',
112                   id    => 'NewFormElementId',
113                   value => 'some value',
114               });
115
116       $method = $form->method
117       $form->method( $new_method )
118           This method is gets/sets the method name used for the HTTP::Request
119           generated.  It is a string like "GET" or "POST".
120
121       $action = $form->action
122       $form->action( $new_action )
123           This method gets/sets the URI which we want to apply the request
124           method to.
125
126       $enctype = $form->enctype
127       $form->enctype( $new_enctype )
128           This method gets/sets the encoding type for the form data.  It is a
129           string like "application/x-www-form-urlencoded" or
130           "multipart/form-data".
131
132       $accept = $form->accept_charset
133       $form->accept_charset( $new_accept )
134           This method gets/sets the list of charset encodings that the server
135           processing the form accepts. Current implementation supports only
136           one-element lists.  Default value is "UNKNOWN" which we interpret
137           as a request to use document charset as specified by the 'charset'
138           parameter of the parse() method.
139
140       $value = $form->attr( $name )
141       $form->attr( $name, $new_value )
142           This method give access to the original HTML attributes of the
143           <form> tag.  The $name should always be passed in lower case.
144
145           Example:
146
147              @f = HTML::Form->parse( $html, $foo );
148              @f = grep $_->attr("id") eq "foo", @f;
149              die "No form named 'foo' found" unless @f;
150              $foo = shift @f;
151
152       $bool = $form->strict
153       $form->strict( $bool )
154           Gets/sets the strict attribute of a form.  If the strict is turned
155           on the methods that change values of the form will croak if you try
156           to set illegal values or modify readonly fields.  The default is
157           not to be strict.
158
159       @inputs = $form->inputs
160           This method returns the list of inputs in the form.  If called in
161           scalar context it returns the number of inputs contained in the
162           form.  See "INPUTS" for what methods are available for the input
163           objects returned.
164
165       $input = $form->find_input( $selector )
166       $input = $form->find_input( $selector, $type )
167       $input = $form->find_input( $selector, $type, $index )
168       @inputs = $form->find_input( $selector )
169       @inputs = $form->find_input( $selector, $type )
170           This method is used to locate specific inputs within the form.  All
171           inputs that match the arguments given are returned.  In scalar
172           context only the first is returned, or "undef" if none match.
173
174           If $selector is not "undef", then the input's name, id, class
175           attribute must match.  A selector prefixed with '#' must match the
176           id attribute of the input.  A selector prefixed with '.' matches
177           the class attribute.  A selector prefixed with '^' or with no
178           prefix matches the name attribute.
179
180           If $type is not "undef", then the input must have the specified
181           type.  The following type names are used: "text", "password",
182           "hidden", "textarea", "file", "image", "submit", "radio",
183           "checkbox" and "option".
184
185           The $index is the sequence number of the input matched where 1 is
186           the first.  If combined with $name and/or $type, then it selects
187           the nth input with the given name and/or type.
188
189       $value = $form->value( $selector )
190       $form->value( $selector, $new_value )
191           The value() method can be used to get/set the value of some input.
192           If strict is enabled and no input has the indicated name, then this
193           method will croak.
194
195           If multiple inputs have the same name, only the first one will be
196           affected.
197
198           The call:
199
200               $form->value('foo')
201
202           is basically a short-hand for:
203
204               $form->find_input('foo')->value;
205
206       @names = $form->param
207       @values = $form->param( $name )
208       $form->param( $name, $value, ... )
209       $form->param( $name, \@values )
210           Alternative interface to examining and setting the values of the
211           form.
212
213           If called without arguments then it returns the names of all the
214           inputs in the form.  The names will not repeat even if multiple
215           inputs have the same name.  In scalar context the number of
216           different names is returned.
217
218           If called with a single argument then it returns the value or
219           values of inputs with the given name.  If called in scalar context
220           only the first value is returned.  If no input exists with the
221           given name, then "undef" is returned.
222
223           If called with 2 or more arguments then it will set values of the
224           named inputs.  This form will croak if no inputs have the given
225           name or if any of the values provided does not fit.  Values can
226           also be provided as a reference to an array.  This form will allow
227           unsetting all values with the given name as well.
228
229           This interface resembles that of the param() function of the CGI
230           module.
231
232       $form->try_others( \&callback )
233           This method will iterate over all permutations of unvisited
234           enumerated values (<select>, <radio>, <checkbox>) and invoke the
235           callback for each.  The callback is passed the $form as argument.
236           The return value from the callback is ignored and the try_others()
237           method itself does not return anything.
238
239       $request = $form->make_request
240           Will return an HTTP::Request object that reflects the current
241           setting of the form.  You might want to use the click() method
242           instead.
243
244       $request = $form->click
245       $request = $form->click( $selector )
246       $request = $form->click( $x, $y )
247       $request = $form->click( $selector, $x, $y )
248           Will "click" on the first clickable input (which will be of type
249           "submit" or "image").  The result of clicking is an HTTP::Request
250           object that can then be passed to LWP::UserAgent if you want to
251           obtain the server response.
252
253           If a $selector is specified, we will click on the first clickable
254           input matching the selector, and the method will croak if no
255           matching clickable input is found.  If $selector is not specified,
256           then it is ok if the form contains no clickable inputs.  In this
257           case the click() method returns the same request as the
258           make_request() method would do.  See description of the
259           find_input() method above for how the $selector is specified.
260
261           If there are multiple clickable inputs with the same name, then
262           there is no way to get the click() method of the "HTML::Form" to
263           click on any but the first.  If you need this you would have to
264           locate the input with find_input() and invoke the click() method on
265           the given input yourself.
266
267           A click coordinate pair can also be provided, but this only makes a
268           difference if you clicked on an image.  The default coordinate is
269           (1,1).  The upper-left corner of the image is (0,0), but some badly
270           coded CGI scripts are known to not recognize this.  Therefore (1,1)
271           was selected as a safer default.
272
273       @kw = $form->form
274           Returns the current setting as a sequence of key/value pairs.  Note
275           that keys might be repeated, which means that some values might be
276           lost if the return values are assigned to a hash.
277
278           In scalar context this method returns the number of key/value pairs
279           generated.
280
281       $form->dump
282           Returns a textual representation of current state of the form.
283           Mainly useful for debugging.  If called in void context, then the
284           dump is printed on STDERR.
285

INPUTS

287       An "HTML::Form" objects contains a sequence of inputs.  References to
288       the inputs can be obtained with the $form->inputs or $form->find_input
289       methods.
290
291       Note that there is not a one-to-one correspondence between input
292       objects and <input> elements in the HTML document.  An input object
293       basically represents a name/value pair, so when multiple HTML elements
294       contribute to the same name/value pair in the submitted form they are
295       combined.
296
297       The input elements that are mapped one-to-one are "text", "textarea",
298       "password", "hidden", "file", "image", "submit" and "checkbox".  For
299       the "radio" and "option" inputs the story is not as simple: All <input
300       type="radio"> elements with the same name will contribute to the same
301       input radio object.  The number of radio input objects will be the same
302       as the number of distinct names used for the <input type="radio">
303       elements.  For a <select> element without the "multiple" attribute
304       there will be one input object of type of "option".  For a <select
305       multiple> element there will be one input object for each contained
306       <option> element.  Each one of these option objects will have the same
307       name.
308
309       The following methods are available for the input objects:
310
311       $input->type
312           Returns the type of this input.  The type is one of the following
313           strings: "text", "password", "hidden", "textarea", "file", "image",
314           "submit", "radio", "checkbox" or "option".
315
316       $name = $input->name
317       $input->name( $new_name )
318           This method can be used to get/set the current name of the input.
319
320       $input->id
321       $input->class
322           These methods can be used to get/set the current id or class
323           attribute for the input.
324
325       $input->selected( $selector )
326           Returns TRUE if the given selector matched the input.  See the
327           description of the find_input() method above for a description of
328           the selector syntax.
329
330       $value = $input->value
331       $input->value( $new_value )
332           This method can be used to get/set the current value of an input.
333
334           If strict is enabled and the input only can take an enumerated list
335           of values, then it is an error to try to set it to something else
336           and the method will croak if you try.
337
338           You will also be able to set the value of read-only inputs, but a
339           warning will be generated if running under "perl -w".
340
341       $autocomplete = $input->autocomplete
342       $input->autocomplete( $new_autocomplete )
343           This method can be used to get/set the current value (if any) of
344           "autcomplete" for the input.
345
346       $input->possible_values
347           Returns a list of all values that an input can take.  For inputs
348           that do not have discrete values, this returns an empty list.
349
350       $input->other_possible_values
351           Returns a list of all values not tried yet.
352
353       $input->value_names
354           For some inputs the values can have names that are different from
355           the values themselves.  The number of names returned by this method
356           will match the number of values reported by
357           $input->possible_values.
358
359           When setting values using the value() method it is also possible to
360           use the value names in place of the value itself.
361
362       $bool = $input->readonly
363       $input->readonly( $bool )
364           This method is used to get/set the value of the readonly attribute.
365           You are allowed to modify the value of readonly inputs, but setting
366           the value will generate some noise when warnings are enabled.
367           Hidden fields always start out readonly.
368
369       $bool = $input->disabled
370       $input->disabled( $bool )
371           This method is used to get/set the value of the disabled attribute.
372           Disabled inputs do not contribute any key/value pairs for the form
373           value.
374
375       $input->form_name_value
376           Returns a (possible empty) list of key/value pairs that should be
377           incorporated in the form value from this input.
378
379       $input->check
380           Some input types represent toggles that can be turned on/off.  This
381           includes "checkbox" and "option" inputs.  Calling this method turns
382           this input on without having to know the value name.  If the input
383           is already on, then nothing happens.
384
385           This has the same effect as:
386
387               $input->value($input->possible_values[1]);
388
389           The input can be turned off with:
390
391               $input->value(undef);
392
393       $input->click($form, $x, $y)
394           Some input types (currently "submit" buttons and "images") can be
395           clicked to submit the form.  The click() method returns the
396           corresponding HTTP::Request object.
397
398       If the input is of type "file", then it has these additional methods:
399
400       $input->file
401           This is just an alias for the value() method.  It sets the filename
402           to read data from.
403
404           For security reasons this field will never be initialized from the
405           parsing of a form.  This prevents the server from triggering
406           stealth uploads of arbitrary files from the client machine.
407
408       $filename = $input->filename
409       $input->filename( $new_filename )
410           This get/sets the filename reported to the server during file
411           upload.  This attribute defaults to the value reported by the
412           file() method.
413
414       $content = $input->content
415       $input->content( $new_content )
416           This get/sets the file content provided to the server during file
417           upload.  This method can be used if you do not want the content to
418           be read from an actual file.
419
420       @headers = $input->headers
421       input->headers($key => $value, .... )
422           This get/set additional header fields describing the file uploaded.
423           This can for instance be used to set the "Content-Type" reported
424           for the file.
425

SEE ALSO

427       LWP, LWP::UserAgent, HTML::Parser
428

AUTHOR

430       Gisle Aas <gisle@activestate.com>
431
433       This software is copyright (c) 1998 by Gisle Aas.
434
435       This is free software; you can redistribute it and/or modify it under
436       the same terms as the Perl 5 programming language system itself.
437
438
439
440perl v5.34.0                      2021-07-22                     HTML::Form(3)
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