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
($base_uri). The base URI is needed to resolve relative action URIs.
The provided HTML document should be a Unicode string (or US-ASCII).
By default HTML::Form assumes that the original document was UTF-8
encoded and thus encode forms that don't specify an explict
*accept-charset* as UTF-8. The charset assumed can be overridden by
providing the `charset' option to parse(). It's a good idea to be
explict about this parameter as well, thus the recommended simplest
invocation becomes:
my @forms = HTML::Form->parse(
Encode::decode($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__}.
`strict => $bool'
Initialize any form objects with the given strict attribute.
$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
*n*th 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.