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

NAME

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

SYNOPSIS

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

DESCRIPTION

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

INPUTS

269       An "HTML::Form" objects contains a sequence of inputs.  References to
270       the inputs can be obtained with the $form->inputs or $form->find_input
271       methods.
272
273       Note that there is not a one-to-one correspondence between input
274       objects and <input> elements in the HTML document.  An input object
275       basically represents a name/value pair, so when multiple HTML elements
276       contribute to the same name/value pair in the submitted form they are
277       combined.
278
279       The input elements that are mapped one-to-one are "text", "textarea",
280       "password", "hidden", "file", "image", "submit" and "checkbox".  For
281       the "radio" and "option" inputs the story is not as simple: All <input
282       type="radio"> elements with the same name will contribute to the same
283       input radio object.  The number of radio input objects will be the same
284       as the number of distinct names used for the <input type="radio">
285       elements.  For a <select> element without the "multiple" attribute
286       there will be one input object of type of "option".  For a <select
287       multiple> element there will be one input object for each contained
288       <option> element.  Each one of these option objects will have the same
289       name.
290
291       The following methods are available for the input objects:
292
293       $input->type
294           Returns the type of this input.  The type is one of the following
295           strings: "text", "password", "hidden", "textarea", "file", "image",
296           "submit", "radio", "checkbox" or "option".
297
298       $name = $input->name
299       $input->name( $new_name )
300           This method can be used to get/set the current name of the input.
301
302       $input->id
303       $input->class
304           These methods can be used to get/set the current id or class
305           attribute for the input.
306
307       $input->selected( $selector )
308           Returns TRUE if the given selector matched the input.  See the
309           description of the find_input() method above for a description of
310           the selector syntax.
311
312       $value = $input->value
313       $input->value( $new_value )
314           This method can be used to get/set the current value of an input.
315
316           If strict is enabled and the input only can take an enumerated list
317           of values, then it is an error to try to set it to something else
318           and the method will croak if you try.
319
320           You will also be able to set the value of read-only inputs, but a
321           warning will be generated if running under "perl -w".
322
323       $autocomplete = $input->autocomplete
324       $input->autocomplete( $new_autocomplete )
325           This method can be used to get/set the current value (if any) of
326           "autcomplete" for the input.
327
328       $input->possible_values
329           Returns a list of all values that an input can take.  For inputs
330           that do not have discrete values, this returns an empty list.
331
332       $input->other_possible_values
333           Returns a list of all values not tried yet.
334
335       $input->value_names
336           For some inputs the values can have names that are different from
337           the values themselves.  The number of names returned by this method
338           will match the number of values reported by
339           $input->possible_values.
340
341           When setting values using the value() method it is also possible to
342           use the value names in place of the value itself.
343
344       $bool = $input->readonly
345       $input->readonly( $bool )
346           This method is used to get/set the value of the readonly attribute.
347           You are allowed to modify the value of readonly inputs, but setting
348           the value will generate some noise when warnings are enabled.
349           Hidden fields always start out readonly.
350
351       $bool = $input->disabled
352       $input->disabled( $bool )
353           This method is used to get/set the value of the disabled attribute.
354           Disabled inputs do not contribute any key/value pairs for the form
355           value.
356
357       $input->form_name_value
358           Returns a (possible empty) list of key/value pairs that should be
359           incorporated in the form value from this input.
360
361       $input->check
362           Some input types represent toggles that can be turned on/off.  This
363           includes "checkbox" and "option" inputs.  Calling this method turns
364           this input on without having to know the value name.  If the input
365           is already on, then nothing happens.
366
367           This has the same effect as:
368
369               $input->value($input->possible_values[1]);
370
371           The input can be turned off with:
372
373               $input->value(undef);
374
375       $input->click($form, $x, $y)
376           Some input types (currently "submit" buttons and "images") can be
377           clicked to submit the form.  The click() method returns the
378           corresponding "HTTP::Request" object.
379
380       If the input is of type "file", then it has these additional methods:
381
382       $input->file
383           This is just an alias for the value() method.  It sets the filename
384           to read data from.
385
386           For security reasons this field will never be initialized from the
387           parsing of a form.  This prevents the server from triggering
388           stealth uploads of arbitrary files from the client machine.
389
390       $filename = $input->filename
391       $input->filename( $new_filename )
392           This get/sets the filename reported to the server during file
393           upload.  This attribute defaults to the value reported by the
394           file() method.
395
396       $content = $input->content
397       $input->content( $new_content )
398           This get/sets the file content provided to the server during file
399           upload.  This method can be used if you do not want the content to
400           be read from an actual file.
401
402       @headers = $input->headers
403       input->headers($key => $value, .... )
404           This get/set additional header fields describing the file uploaded.
405           This can for instance be used to set the "Content-Type" reported
406           for the file.
407

SEE ALSO

409       LWP, LWP::UserAgent, HTML::Parser
410
412       Copyright 1998-2008 Gisle Aas.
413
414       This library is free software; you can redistribute it and/or modify it
415       under the same terms as Perl itself.
416
417
418
419perl v5.30.0                      2019-07-26                     HTML::Form(3)
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