1CGI::Application::PlugiUns:e:rFoCromnSttraitbeu(t3e)d PeCrGlI:D:oAcpupmleinctaattiioonn::Plugin::FormState(3)
2
6 CGI::Application::Plugin::FormState - Store Form State without Hidden
7 Fields
8
10 Version 0.12
11
13 FormState is just a temporary stash that you can use for storing and
14 retrieving private parameters in your multi-page form.
15 use CGI::Application::Plugin::FormState;
17 my $form = <<EOF;
19 <form action="app.cgi">
20 <input type="hidden" name="run_mode" value="form_process_runmode">
21 <input type="hidden" name="cap_form_state" value="<tmpl_var cap_form_state>">
22 ...
23 </form>
24 EOF
25 sub form_display_runmode {
27 my $self = shift;
28 # Store some parameters
30 $self->form_state->param('name' => 'Road Runner');
31 $self->form_state->param('occupation' => 'Having Fun');
32 my $t = $self->load_tmpl(scalarref => \$form);
34 return $t->output;
35 }
37 sub form_process_runmode {
39 my $self = shift;
40 # Retrieve some parameters
42 print $self->form_state->param('name'); # 'Road Runner'
43 print $self->form_state->param('occupation'); # 'Having Fun'
44 }
45
47 This is a more complete example, using
48 CGI::Application::Plugin::ValidateRM.
49 use CGI::Application::Plugin::Session;
51 use CGI::Application::Plugin::FormState;
52 use CGI::Application::Plugin::ValidateRM;
53 my $form = <<EOF;
55 <form action="app.cgi">
56 <input type="hidden" name="run_mode" value="my_form_process">
57 <input type="hidden" name="cap_form_state" value="<tmpl_var cap_form_state>">
58 ...
59 </form>
60 EOF
61 sub my_form_display {
63 my $self = shift;
64 my $errs = shift;
65 my $t = $self->load_tmpl(scalarref => \$form);
66 # Stash some data into it
68 $self->form_state->param('name' => 'Wile E. Coyote');
69 $self->form_state->param('occupation' => 'Mining Engineer');
70 # Normal ValidateRM error handling
72 $t->param($errs) if $errs;
73 return $t->output;
74 }
75 sub my_form_process {
77 my $self;
78 # Normal ValidateRM validation
80 my ($results, $err_page) = $self->check_rm('my_form_display','_my_form_profile');
81 return $err_page if $err_page;
82 # The data from the submitted form
84 my $params = $self->dfv_results;
85 $params->{'name'} = $self->form_state->param('name'); # 'Wile E. Coyote'
87 $params->{'occupation'} = $self->form_state->param('occupation'); # 'Mining Engineer'
88 # Now do something interesting with $params
91 # ...
92 my $t = $self->load_tmpl('success.html');
95 return $t->output;
96 }
97 # Standard ValiateRM profile
99 sub _my_form_profile {
100 return {
101 required => 'email',
102 msgs => {
103 any_errors => 'some_errors',
104 prefix => 'err_',
105 },
106 };
107 }
108
110 "CGI::Application::Plugin::FormState" provides a temporary storage area
111 within the user's session for storing form-related data.
112 The main use of this is for multi-page forms. Instead of using hidden
114 fields to store data related to the form, you store and retrieve values
115 from the form state.
116 In the first instance of your app:
118 $self->form_state->param('some_name' => 'some_value');
120 $self->form_state->param('some_other_name' => 'some_other_value');
121 And later, in a different instance of your app:
123 $val1 = $self->form_state->param('some_name');
125 $val2 = $self->form_state->param('some_other_name');
126 To connect the first instance and the second, you put a single hidden
128 field in your template:
129 <input type="hidden" name="cap_form_state" value="<tmpl_var my_storage_name>">
131 You don't have to worry about creating the template param
133 "cap_form_state"; it is added automatically to your template parameters
134 via the "load_tmpl" hook.
135 If you want to use a parameter other than "cap_form_state" you can do
137 so via the "name" parameter to "form_state-"config>.
138 If you're skeptical about whether all this abstraction is a good idea,
140 see "MOTIVATION", below.
141
143 You can include the form_state hash in a link:
144 my $link = '/app.cgi?rm=list&cap_form_state=' . $self->form_state->id;
146 If you use CGI::Application::Plugin::Redirect, you can easily create
148 redirect this way:
149 $self->redirect('/app.cgi?rm=list&cap_form_state=' . $self->form_state->id);
151 If you also use CGI::Application::Plugin::LinkIntegrity it is as simple
153 as:
154 $self->redirect($self->link('/app.cgi', 'rm' => 'list', 'cap_form_state' => $self->form_state->id));
156 Or, in the case of a link to the currently running app:
158 $self->redirect($self->self_link('rm' => 'list', 'cap_form_state' => $self->form_state->id));
160
162 When you call "$self->form_state" for the first time, a top-level key
163 is created in the user's session. This key contains a random, hard-to-
164 guess element. It might look something like:
165 form_state_cap_form_state_84eb13cfed01764d9c401219faa56d53
167 All data you place in the form state with "param" is stored in the
169 user's session under this key.
170 You pass the name of this key on to the next instance of your
172 application by means of a hidden field in your form:
173 <input type="hidden" name="cap_form_state" value="<tmpl_var cap_form_state>">
175 You manually put this hidden field in your template. The template
177 parameter "cap_form_state" is automatically added to your template
178 parameters via the "load_tmpl" hook. It contains the random, hard-to-
179 guess portion (e.g. "84eb13cfed01764d9c401219faa56d53"). When the
180 template is filled, the hidden field will look something like this:
181 <input type="hidden" name="cap_form_state" value="84eb13cfed01764d9c401219faa56d53">
183 Since all values are stored on the server in the user's session, the
185 user can't tamper with any of them.
186 To keep old form_data from cluttering up the user's session, the system
188 uses CGI::Session's "expire" feature to expire old form state keys
189 after a reasonable amount of time has passed (2 days by default).
190 You can manually delete a form state storage by calling:
192 $self->form_state->delete;
194
196 config(%options)
197 Sets defaults for the plugin.
198 Calling config is purely optional, since the defaults should be
200 fine most purposes.
201 $self->form_state->config('name' => 'storage_names', 'expires' => '3d')
203 The following options are allowed:
205 name
207 Sets the name of the default form state storage. This name is
208 used for the key in the user's session, for the name of hidden
209 form field, and the template parameter used to fill the hidden
210 form field. So if you set the "name" to "foo":
211 $self->form_state_config('name' => 'foo');
213 then the hidden field in your template should look like this:
215 <input type="hidden" name="foo" value="<tmpl_var foo>">
217 and the key in the user's session would look something like
219 this:
220 form_state_foo_84eb13cfed01764d9c401219faa56d53
222 expires
224 Indicates when form state storage keys should expire and
225 disappear from the user's session. Uses the same format as
226 CGI::Session's "expire". Defaults to 2 days ('2d'). To cancel
227 expiration and make the form state last as long as the user's
228 session does, use:
229 $self->form_state_config('expires' => 0);
231 param
233 Read and set values in the form state storage. It acts like the
234 "param" method typically does in modules such as CGI,
235 CGI::Application, CGI::Session, "HTML::Template" etc.
236 # set a value
238 $self->form_state->param('some_name' => 'some_value');
239 # retrieve a value
241 my $val = $self->form_state->param('some_name');
242 # set multiple values
244 $self->form_state->param(
245 'some_name' => 'some_value',
246 'some_other_name' => 'some_other_value',
247 );
248 # retrive the names of all the keys
250 my @keys = $self->form_state->param;
251 clear_params
253 Clear all of the values in the form state storage:
254 $self->form_state->param('name' => 'Road Runner');
256 $self->form_state->clear_params;
257 print $self->form_state->param('name'); # undef
258 delete
260 Deletes the form_state storage from the user's session.
261 id Returns the current value of the storage param - the "hard to
263 guess" portion of the session key.
264 my $id = $self->form_state->id;
266 name
268 Returns the current name being used for storage. Defaults to
269 "cap_form_state".
270 my $name = $self->form_state->name;
272 session_key
274 Returns the full key used for storage in the user's session.
275 my $key = $self->form_state->session_key;
277 # Get the full form state hash
279 my $data = $self->session->param($key);
280 The following can be used to debug the form_state data:
282 use Data::Dumper;
284 print STDERR Dumper $self->session->param($self->form_state->session_key);
285
287 Why not just use hidden fields?
288 Hidden fields are not secure. The end user could save a local copy of
289 your form, change the hidden fields and tamper with your app's form
290 state.
291 Why not just use the user's session?
293 With "CGI::Application::Plugin::FormState" the data is associated with
294 a particular instance of a form, not with the user. If the user gives
295 up halfway through your multi-page form, you don't want their session
296 to be cluttered up with the incomplete form state data.
297 If a user opens up your application in two browser windows (both
299 sharing the same user session), each window should have it's own
300 independent form state.
301 For instance, in an email application the user might have one window
303 open for the inbox and another open for the outbox. If you store the
304 value of "current_mailbox" in the user's session, then one of these
305 windows will go to the wrong mailbox.
306 Finally, the user's session probably sticks around longer than the form
308 state should.
309
311 Michael Graham, "<mag-perl@occamstoothbrush.com>"
312
314 Please report any bugs or feature requests to
315 "bug-cgi-application-plugin-formstate@rt.cpan.org", or through the web
316 interface at <http://rt.cpan.org>. I will be notified, and then you'll
317 automatically be notified of progress on your bug as I make changes.
318
320 Thanks to Richard Dice and Cees Hek for helping me sort out the issues
321 with this approach.
322 The informative error message text used for when this module is loaded
324 before your app actually @ISA "CGI::Application" object was stolen from
325 Cees's CGI::Application::Plugin::TT module.
326
328 Copyright 2005 Michael Graham, All Rights Reserved.
329 This program is free software; you can redistribute it and/or modify it
331 under the same terms as Perl itself.
332perl v5.34.0 2021-07C-G2I2::Application::Plugin::FormState(3)