1HTML::Form(3) User Contributed Perl Documentation HTML::Form(3)
2
6 HTML::Form - Class that represents an HTML form element
7
9 use HTML::Form;
10 $form = HTML::Form->parse($html, $base_uri);
11 $form->value(query => "Perl");
12 use LWP::UserAgent;
14 $ua = LWP::UserAgent->new;
15 $response = $ua->request($form->click);
16
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 The following methods are available:
26 @forms = HTML::Form->parse( $html_document, $base_uri )
28 @forms = HTML::Form->parse( $html_document, base => $base_uri, %opt )
29 @forms = HTML::Form->parse( $response, %opt )
30 The parse() class method will parse an HTML document and build up
31 "HTML::Form" objects for each <form> element found. If called in
32 scalar context only returns the first <form>. Returns an empty
33 list if there are no forms to be found.
34 The required arguments is the HTML document to parse
36 ($html_document) and the URI used to retrieve the document
37 ($base_uri). The base URI is needed to resolve relative action
38 URIs. The provided HTML document should be a Unicode string (or
39 US-ASCII).
40 By default HTML::Form assumes that the original document was UTF-8
42 encoded and thus encode forms that don't specify an explicit
43 accept-charset as UTF-8. The charset assumed can be overridden by
44 providing the "charset" option to parse(). It's a good idea to be
45 explicit about this parameter as well, thus the recommended
46 simplest invocation becomes:
47 my @forms = HTML::Form->parse(
49 Encode::decode($encoding, $html_document_bytes),
50 base => $base_uri,
51 charset => $encoding,
52 );
53 If the document was retrieved with LWP then the response object
55 provide methods to obtain a proper value for "base" and "charset":
56 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 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 my $ua = LWP::UserAgent->new;
69 my $response = $ua->get("http://www.example.com/form.html");
70 my @forms = HTML::Form->parse($response);
71 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 Additional options might be passed in to control how the parse
77 method behaves. The following are all the options currently
78 recognized:
79 "base => $uri"
81 This is the URI used to retrieve the original document. This
82 option is not optional ;-)
83 "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 "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 "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 $form->push_input( $type, \%attr, $verbose )
101 This method adds additional inputs to the form. The first argument
102 is the type of input (e.g. hidden, option, etc.). The second
103 argument is a reference to a hash of the input attributes. The
104 third argument is optional, and will issue warnings about unknown
105 input types.
106 Example:
108 push_input( 'hidden', {
110 name => 'NewFormElement',
111 id => 'NewFormElementId',
112 value => 'some value',
113 });
114 $method = $form->method
116 $form->method( $new_method )
117 This method is gets/sets the method name used for the
118 "HTTP::Request" generated. It is a string like "GET" or "POST".
119 $action = $form->action
121 $form->action( $new_action )
122 This method gets/sets the URI which we want to apply the request
123 method to.
124 $enctype = $form->enctype
126 $form->enctype( $new_enctype )
127 This method gets/sets the encoding type for the form data. It is a
128 string like "application/x-www-form-urlencoded" or
129 "multipart/form-data".
130 $accept = $form->accept_charset
132 $form->accept_charset( $new_accept )
133 This method gets/sets the list of charset encodings that the server
134 processing the form accepts. Current implementation supports only
135 one-element lists. Default value is "UNKNOWN" which we interpret
136 as a request to use document charset as specified by the 'charset'
137 parameter of the parse() method.
138 $value = $form->attr( $name )
140 $form->attr( $name, $new_value )
141 This method give access to the original HTML attributes of the
142 <form> tag. The $name should always be passed in lower case.
143 Example:
145 @f = HTML::Form->parse( $html, $foo );
147 @f = grep $_->attr("id") eq "foo", @f;
148 die "No form named 'foo' found" unless @f;
149 $foo = shift @f;
150 $bool = $form->strict
152 $form->strict( $bool )
153 Gets/sets the strict attribute of a form. If the strict is turned
154 on the methods that change values of the form will croak if you try
155 to set illegal values or modify readonly fields. The default is
156 not to be strict.
157 @inputs = $form->inputs
159 This method returns the list of inputs in the form. If called in
160 scalar context it returns the number of inputs contained in the
161 form. See "INPUTS" for what methods are available for the input
162 objects returned.
163 $input = $form->find_input( $selector )
165 $input = $form->find_input( $selector, $type )
166 $input = $form->find_input( $selector, $type, $index )
167 This method is used to locate specific inputs within the form. All
168 inputs that match the arguments given are returned. In scalar
169 context only the first is returned, or "undef" if none match.
170 If $selector is not "undef", then the input's name, id, class
172 attribute must match. A selector prefixed with '#' must match the
173 id attribute of the input. A selector prefixed with '.' matches
174 the class attribute. A selector prefixed with '^' or with no
175 prefix matches the name attribute.
176 If $type is not "undef", then the input must have the specified
178 type. The following type names are used: "text", "password",
179 "hidden", "textarea", "file", "image", "submit", "radio",
180 "checkbox" and "option".
181 The $index is the sequence number of the input matched where 1 is
183 the first. If combined with $name and/or $type, then it selects
184 the nth input with the given name and/or type.
185 $value = $form->value( $selector )
187 $form->value( $selector, $new_value )
188 The value() method can be used to get/set the value of some input.
189 If strict is enabled and no input has the indicated name, then this
190 method will croak.
191 If multiple inputs have the same name, only the first one will be
193 affected.
194 The call:
196 $form->value('foo')
198 is basically a short-hand for:
200 $form->find_input('foo')->value;
202 @names = $form->param
204 @values = $form->param( $name )
205 $form->param( $name, $value, ... )
206 $form->param( $name, \@values )
207 Alternative interface to examining and setting the values of the
208 form.
209 If called without arguments then it returns the names of all the
211 inputs in the form. The names will not repeat even if multiple
212 inputs have the same name. In scalar context the number of
213 different names is returned.
214 If called with a single argument then it returns the value or
216 values of inputs with the given name. If called in scalar context
217 only the first value is returned. If no input exists with the
218 given name, then "undef" is returned.
219 If called with 2 or more arguments then it will set values of the
221 named inputs. This form will croak if no inputs have the given
222 name or if any of the values provided does not fit. Values can
223 also be provided as a reference to an array. This form will allow
224 unsetting all values with the given name as well.
225 This interface resembles that of the param() function of the CGI
227 module.
228 $form->try_others( \&callback )
230 This method will iterate over all permutations of unvisited
231 enumerated values (<select>, <radio>, <checkbox>) and invoke the
232 callback for each. The callback is passed the $form as argument.
233 The return value from the callback is ignored and the try_others()
234 method itself does not return anything.
235 $request = $form->make_request
237 Will return an "HTTP::Request" object that reflects the current
238 setting of the form. You might want to use the click() method
239 instead.
240 $request = $form->click
242 $request = $form->click( $selector )
243 $request = $form->click( $x, $y )
244 $request = $form->click( $selector, $x, $y )
245 Will "click" on the first clickable input (which will be of type
246 "submit" or "image"). The result of clicking is an "HTTP::Request"
247 object that can then be passed to "LWP::UserAgent" if you want to
248 obtain the server response.
249 If a $selector is specified, we will click on the first clickable
251 input matching the selector, and the method will croak if no
252 matching clickable input is found. If $selector is not specified,
253 then it is ok if the form contains no clickable inputs. In this
254 case the click() method returns the same request as the
255 make_request() method would do. See description of the
256 find_input() method above for how the $selector is specified.
257 If there are multiple clickable inputs with the same name, then
259 there is no way to get the click() method of the "HTML::Form" to
260 click on any but the first. If you need this you would have to
261 locate the input with find_input() and invoke the click() method on
262 the given input yourself.
263 A click coordinate pair can also be provided, but this only makes a
265 difference if you clicked on an image. The default coordinate is
266 (1,1). The upper-left corner of the image is (0,0), but some badly
267 coded CGI scripts are known to not recognize this. Therefore (1,1)
268 was selected as a safer default.
269 @kw = $form->form
271 Returns the current setting as a sequence of key/value pairs. Note
272 that keys might be repeated, which means that some values might be
273 lost if the return values are assigned to a hash.
274 In scalar context this method returns the number of key/value pairs
276 generated.
277 $form->dump
279 Returns a textual representation of current state of the form.
280 Mainly useful for debugging. If called in void context, then the
281 dump is printed on STDERR.
282
284 An "HTML::Form" objects contains a sequence of inputs. References to
285 the inputs can be obtained with the $form->inputs or $form->find_input
286 methods.
287 Note that there is not a one-to-one correspondence between input
289 objects and <input> elements in the HTML document. An input object
290 basically represents a name/value pair, so when multiple HTML elements
291 contribute to the same name/value pair in the submitted form they are
292 combined.
293 The input elements that are mapped one-to-one are "text", "textarea",
295 "password", "hidden", "file", "image", "submit" and "checkbox". For
296 the "radio" and "option" inputs the story is not as simple: All <input
297 type="radio"> elements with the same name will contribute to the same
298 input radio object. The number of radio input objects will be the same
299 as the number of distinct names used for the <input type="radio">
300 elements. For a <select> element without the "multiple" attribute
301 there will be one input object of type of "option". For a <select
302 multiple> element there will be one input object for each contained
303 <option> element. Each one of these option objects will have the same
304 name.
305 The following methods are available for the input objects:
307 $input->type
309 Returns the type of this input. The type is one of the following
310 strings: "text", "password", "hidden", "textarea", "file", "image",
311 "submit", "radio", "checkbox" or "option".
312 $name = $input->name
314 $input->name( $new_name )
315 This method can be used to get/set the current name of the input.
316 $input->id
318 $input->class
319 These methods can be used to get/set the current id or class
320 attribute for the input.
321 $input->selected( $selector )
323 Returns TRUE if the given selector matched the input. See the
324 description of the find_input() method above for a description of
325 the selector syntax.
326 $value = $input->value
328 $input->value( $new_value )
329 This method can be used to get/set the current value of an input.
330 If strict is enabled and the input only can take an enumerated list
332 of values, then it is an error to try to set it to something else
333 and the method will croak if you try.
334 You will also be able to set the value of read-only inputs, but a
336 warning will be generated if running under "perl -w".
337 $autocomplete = $input->autocomplete
339 $input->autocomplete( $new_autocomplete )
340 This method can be used to get/set the current value (if any) of
341 "autcomplete" for the input.
342 $input->possible_values
344 Returns a list of all values that an input can take. For inputs
345 that do not have discrete values, this returns an empty list.
346 $input->other_possible_values
348 Returns a list of all values not tried yet.
349 $input->value_names
351 For some inputs the values can have names that are different from
352 the values themselves. The number of names returned by this method
353 will match the number of values reported by
354 $input->possible_values.
355 When setting values using the value() method it is also possible to
357 use the value names in place of the value itself.
358 $bool = $input->readonly
360 $input->readonly( $bool )
361 This method is used to get/set the value of the readonly attribute.
362 You are allowed to modify the value of readonly inputs, but setting
363 the value will generate some noise when warnings are enabled.
364 Hidden fields always start out readonly.
365 $bool = $input->disabled
367 $input->disabled( $bool )
368 This method is used to get/set the value of the disabled attribute.
369 Disabled inputs do not contribute any key/value pairs for the form
370 value.
371 $input->form_name_value
373 Returns a (possible empty) list of key/value pairs that should be
374 incorporated in the form value from this input.
375 $input->check
377 Some input types represent toggles that can be turned on/off. This
378 includes "checkbox" and "option" inputs. Calling this method turns
379 this input on without having to know the value name. If the input
380 is already on, then nothing happens.
381 This has the same effect as:
383 $input->value($input->possible_values[1]);
385 The input can be turned off with:
387 $input->value(undef);
389 $input->click($form, $x, $y)
391 Some input types (currently "submit" buttons and "images") can be
392 clicked to submit the form. The click() method returns the
393 corresponding "HTTP::Request" object.
394 If the input is of type "file", then it has these additional methods:
396 $input->file
398 This is just an alias for the value() method. It sets the filename
399 to read data from.
400 For security reasons this field will never be initialized from the
402 parsing of a form. This prevents the server from triggering
403 stealth uploads of arbitrary files from the client machine.
404 $filename = $input->filename
406 $input->filename( $new_filename )
407 This get/sets the filename reported to the server during file
408 upload. This attribute defaults to the value reported by the
409 file() method.
410 $content = $input->content
412 $input->content( $new_content )
413 This get/sets the file content provided to the server during file
414 upload. This method can be used if you do not want the content to
415 be read from an actual file.
416 @headers = $input->headers
418 input->headers($key => $value, .... )
419 This get/set additional header fields describing the file uploaded.
420 This can for instance be used to set the "Content-Type" reported
421 for the file.
422
424 LWP, LWP::UserAgent, HTML::Parser
425
427 Copyright 1998-2008 Gisle Aas.
428 This library is free software; you can redistribute it and/or modify it
430 under the same terms as Perl itself.
431perl v5.30.1 2020-01-30 HTML::Form(3)