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 ($base_uri). The base URI is needed to resolve relative action
38 URIs. The provided HTML document should be a Unicode string (or
39 US-ASCII).
40 By default HTML::Form assumes that the original document was UTF-8
42 encoded and thus encode forms that don't specify an explict accept-
43 charset as UTF-8. The charset assumed can be overridden by
44 providing the "charset" option to parse(). It's a good idea to be
45 explict about this parameter as well, thus the recommended simplest
46 invocation becomes:
47 my @forms = HTML::Form->parse(
49 Encode::decode($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 retrive 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__}.
92 "strict => $bool"
94 Initialize any form objects with the given strict attribute.
95 $method = $form->method
97 $form->method( $new_method )
98 This method is gets/sets the method name used for the
99 "HTTP::Request" generated. It is a string like "GET" or "POST".
100 $action = $form->action
102 $form->action( $new_action )
103 This method gets/sets the URI which we want to apply the request
104 method to.
105 $enctype = $form->enctype
107 $form->enctype( $new_enctype )
108 This method gets/sets the encoding type for the form data. It is a
109 string like "application/x-www-form-urlencoded" or
110 "multipart/form-data".
111 $accept = $form->accept_charset
113 $form->accept_charset( $new_accept )
114 This method gets/sets the list of charset encodings that the server
115 processing the form accepts. Current implementation supports only
116 one-element lists. Default value is "UNKNOWN" which we interpret
117 as a request to use document charset as specified by the 'charset'
118 parameter of the parse() method. To encode character strings you
119 should have modern perl with Encode module. On older perls the
120 setting of this attribute has no effect.
121 $value = $form->attr( $name )
123 $form->attr( $name, $new_value )
124 This method give access to the original HTML attributes of the
125 <form> tag. The $name should always be passed in lower case.
126 Example:
128 @f = HTML::Form->parse( $html, $foo );
130 @f = grep $_->attr("id") eq "foo", @f;
131 die "No form named 'foo' found" unless @f;
132 $foo = shift @f;
133 $bool = $form->strict
135 $form->strict( $bool )
136 Gets/sets the strict attribute of a form. If the strict is turned
137 on the methods that change values of the form will croak if you try
138 to set illegal values or modify readonly fields. The default is
139 not to be strict.
140 @inputs = $form->inputs
142 This method returns the list of inputs in the form. If called in
143 scalar context it returns the number of inputs contained in the
144 form. See "INPUTS" for what methods are available for the input
145 objects returned.
146 $input = $form->find_input( $selector )
148 $input = $form->find_input( $selector, $type )
149 $input = $form->find_input( $selector, $type, $index )
150 This method is used to locate specific inputs within the form. All
151 inputs that match the arguments given are returned. In scalar
152 context only the first is returned, or "undef" if none match.
153 If $selector is specified, then the input's name, id, class
155 attribute must match. A selector prefixed with '#' must match the
156 id attribute of the input. A selector prefixed with '.' matches
157 the class attribute. A selector prefixed with '^' or with no
158 prefix matches the name attribute.
159 If $type is specified, then the input must have the specified type.
161 The following type names are used: "text", "password", "hidden",
162 "textarea", "file", "image", "submit", "radio", "checkbox" and
163 "option".
164 The $index is the sequence number of the input matched where 1 is
166 the first. If combined with $name and/or $type then it select the
167 nth input with the given name and/or type.
168 $value = $form->value( $selector )
170 $form->value( $selector, $new_value )
171 The value() method can be used to get/set the value of some input.
172 If strict is enabled and no input has the indicated name, then this
173 method will croak.
174 If multiple inputs have the same name, only the first one will be
176 affected.
177 The call:
179 $form->value('foo')
181 is basically a short-hand for:
183 $form->find_input('foo')->value;
185 @names = $form->param
187 @values = $form->param( $name )
188 $form->param( $name, $value, ... )
189 $form->param( $name, \@values )
190 Alternative interface to examining and setting the values of the
191 form.
192 If called without arguments then it returns the names of all the
194 inputs in the form. The names will not repeat even if multiple
195 inputs have the same name. In scalar context the number of
196 different names is returned.
197 If called with a single argument then it returns the value or
199 values of inputs with the given name. If called in scalar context
200 only the first value is returned. If no input exists with the
201 given name, then "undef" is returned.
202 If called with 2 or more arguments then it will set values of the
204 named inputs. This form will croak if no inputs have the given
205 name or if any of the values provided does not fit. Values can
206 also be provided as a reference to an array. This form will allow
207 unsetting all values with the given name as well.
208 This interface resembles that of the param() function of the CGI
210 module.
211 $form->try_others( \&callback )
213 This method will iterate over all permutations of unvisited
214 enumerated values (<select>, <radio>, <checkbox>) and invoke the
215 callback for each. The callback is passed the $form as argument.
216 The return value from the callback is ignored and the try_others()
217 method itself does not return anything.
218 $request = $form->make_request
220 Will return an "HTTP::Request" object that reflects the current
221 setting of the form. You might want to use the click() method
222 instead.
223 $request = $form->click
225 $request = $form->click( $selector )
226 $request = $form->click( $x, $y )
227 $request = $form->click( $selector, $x, $y )
228 Will "click" on the first clickable input (which will be of type
229 "submit" or "image"). The result of clicking is an "HTTP::Request"
230 object that can then be passed to "LWP::UserAgent" if you want to
231 obtain the server response.
232 If a $selector is specified, we will click on the first clickable
234 input matching the selector, and the method will croak if no
235 matching clickable input is found. If $selector is not specified,
236 then it is ok if the form contains no clickable inputs. In this
237 case the click() method returns the same request as the
238 make_request() method would do. See description of the
239 find_input() method above for how the $selector is specified.
240 If there are multiple clickable inputs with the same name, then
242 there is no way to get the click() method of the "HTML::Form" to
243 click on any but the first. If you need this you would have to
244 locate the input with find_input() and invoke the click() method on
245 the given input yourself.
246 A click coordinate pair can also be provided, but this only makes a
248 difference if you clicked on an image. The default coordinate is
249 (1,1). The upper-left corner of the image is (0,0), but some badly
250 coded CGI scripts are known to not recognize this. Therefore (1,1)
251 was selected as a safer default.
252 @kw = $form->form
254 Returns the current setting as a sequence of key/value pairs. Note
255 that keys might be repeated, which means that some values might be
256 lost if the return values are assigned to a hash.
257 In scalar context this method returns the number of key/value pairs
259 generated.
260 $form->dump
262 Returns a textual representation of current state of the form.
263 Mainly useful for debugging. If called in void context, then the
264 dump is printed on STDERR.
265
267 An "HTML::Form" objects contains a sequence of inputs. References to
268 the inputs can be obtained with the $form->inputs or $form->find_input
269 methods.
270 Note that there is not a one-to-one correspondence between input
272 objects and <input> elements in the HTML document. An input object
273 basically represents a name/value pair, so when multiple HTML elements
274 contribute to the same name/value pair in the submitted form they are
275 combined.
276 The input elements that are mapped one-to-one are "text", "textarea",
278 "password", "hidden", "file", "image", "submit" and "checkbox". For
279 the "radio" and "option" inputs the story is not as simple: All <input
280 type="radio"> elements with the same name will contribute to the same
281 input radio object. The number of radio input objects will be the same
282 as the number of distinct names used for the <input type="radio">
283 elements. For a <select> element without the "multiple" attribute
284 there will be one input object of type of "option". For a <select
285 multiple> element there will be one input object for each contained
286 <option> element. Each one of these option objects will have the same
287 name.
288 The following methods are available for the input objects:
290 $input->type
292 Returns the type of this input. The type is one of the following
293 strings: "text", "password", "hidden", "textarea", "file", "image",
294 "submit", "radio", "checkbox" or "option".
295 $name = $input->name
297 $input->name( $new_name )
298 This method can be used to get/set the current name of the input.
299 $input->id
301 $input->class
302 These methods can be used to get/set the current id or class
303 attribute for the input.
304 $input->selected( $selector )
306 Returns TRUE if the given selector matched the input. See the
307 description of the find_input() method above for a description of
308 the selector syntax.
309 $value = $input->value
311 $input->value( $new_value )
312 This method can be used to get/set the current value of an input.
313 If strict is enabled and the input only can take an enumerated list
315 of values, then it is an error to try to set it to something else
316 and the method will croak if you try.
317 You will also be able to set the value of read-only inputs, but a
319 warning will be generated if running under "perl -w".
320 $input->possible_values
322 Returns a list of all values that an input can take. For inputs
323 that do not have discrete values, this returns an empty list.
324 $input->other_possible_values
326 Returns a list of all values not tried yet.
327 $input->value_names
329 For some inputs the values can have names that are different from
330 the values themselves. The number of names returned by this method
331 will match the number of values reported by
332 $input->possible_values.
333 When setting values using the value() method it is also possible to
335 use the value names in place of the value itself.
336 $bool = $input->readonly
338 $input->readonly( $bool )
339 This method is used to get/set the value of the readonly attribute.
340 You are allowed to modify the value of readonly inputs, but setting
341 the value will generate some noise when warnings are enabled.
342 Hidden fields always start out readonly.
343 $bool = $input->disabled
345 $input->disabled( $bool )
346 This method is used to get/set the value of the disabled attribute.
347 Disabled inputs do not contribute any key/value pairs for the form
348 value.
349 $input->form_name_value
351 Returns a (possible empty) list of key/value pairs that should be
352 incorporated in the form value from this input.
353 $input->check
355 Some input types represent toggles that can be turned on/off. This
356 includes "checkbox" and "option" inputs. Calling this method turns
357 this input on without having to know the value name. If the input
358 is already on, then nothing happens.
359 This has the same effect as:
361 $input->value($input->possible_values[1]);
363 The input can be turned off with:
365 $input->value(undef);
367 $input->click($form, $x, $y)
369 Some input types (currently "submit" buttons and "images") can be
370 clicked to submit the form. The click() method returns the
371 corresponding "HTTP::Request" object.
372 If the input is of type "file", then it has these additional methods:
374 $input->file
376 This is just an alias for the value() method. It sets the filename
377 to read data from.
378 For security reasons this field will never be initialized from the
380 parsing of a form. This prevents the server from triggering
381 stealth uploads of arbitrary files from the client machine.
382 $filename = $input->filename
384 $input->filename( $new_filename )
385 This get/sets the filename reported to the server during file
386 upload. This attribute defaults to the value reported by the
387 file() method.
388 $content = $input->content
390 $input->content( $new_content )
391 This get/sets the file content provided to the server during file
392 upload. This method can be used if you do not want the content to
393 be read from an actual file.
394 @headers = $input->headers
396 input->headers($key => $value, .... )
397 This get/set additional header fields describing the file uploaded.
398 This can for instance be used to set the "Content-Type" reported
399 for the file.
400
402 LWP, LWP::UserAgent, HTML::Parser
403
405 Copyright 1998-2008 Gisle Aas.
406 This library is free software; you can redistribute it and/or modify it
408 under the same terms as Perl itself.
409perl v5.12.4 2009-07-07 HTML::Form(3)