1CGI::Application::PlugiUns:e:rFoCrownatrrdi(b3u)ted PerlCGDIo:c:uAmpepnltiactaitoinon::Plugin::Forward(3)
2
6 CGI::Application::Plugin::Forward - Pass control from one run mode to
7 another
8
10 Version 1.06
11
13 use base 'CGI::Application';
14 use CGI::Application::Plugin::Forward;
15 sub setup {
17 my $self = shift;
18 $self->run_modes([qw(
19 start
20 second_runmode
21 )]);
22 }
23 sub start {
24 my $self = shift;
25 return $self->forward('second_runmode');
26 }
27 sub second_runmode {
28 my $self = shift;
29 my $rm = $self->get_current_runmode; # 'second_runmode'
31 }
33
35 The forward method passes control to another run mode and returns its
36 output. This is equivalent to calling "$self->$other_runmode", except
37 that CGI::Application's internal value of the current run mode is
38 updated.
39 This means that calling "$self->get_current_runmode" after calling
41 "forward" will return the name of the new run mode. This is useful for
42 modules that depend on the name of the current run mode such as
43 CGI::Application::Plugin::AnyTemplate.
44 For example, here's how to pass control to a run mode named
46 "other_action" from "start" while updating the value of
47 "current_run_mode":
48 sub setup {
50 my $self = shift;
51 $self->run_modes({
52 start => 'start',
53 other_action => 'other_method',
54 });
55 }
56 sub start {
57 my $self = shift;
58 return $self->forward('other_action');
59 }
60 sub other_method {
61 my $self = shift;
62 my $rm = $self->get_current_runmode; # 'other_action'
64 }
65 Note that forward accepts the name of the run mode (in this case
67 'other_action'), which might not be the same as the name of the method
68 that handles the run mode (in this case 'other_method')
69 You can still call "$self->other_method" directly, but
71 "current_run_mode" will not be updated:
72 sub setup {
74 my $self = shift;
75 $self->run_modes({
76 start => 'start',
77 other_action => 'other_method',
78 });
79 }
80 sub start {
81 my $self = shift;
82 return $self->other_method;
83 }
84 sub other_method {
85 my $self = shift;
86 my $rm = $self->get_current_runmode; # 'start'
88 }
89 Forward will work with coderef-based runmodes as well:
91 sub setup {
93 my $self = shift;
94 $self->run_modes({
95 start => 'start',
96 anon_action => sub {
97 my $self = shift;
98 my $rm = $self->get_current_runmode; # 'anon_action'
99 },
100 });
101 }
102 sub start {
103 my $self = shift;
104 return $self->forward('anon_action');
105 }
106
108 Calling "forward" changes the run mode of your application, but it
109 stays within the same HTTP request.
110 To redirect to a new runmode using a completely new web request, you
112 might consider using the "redirect" method provided by
113 CGI::Application::Plugin::Redirect.
114 The advantage of using an external redirect as opposed to an internal
116 forward is that it provides a 'clean break' between pages.
117 For instance, in a typical BREAD application (Browse, Read, Edit, Add,
119 Delete), after the user completes an action, you usually return the
120 user to the Browse list. For instance, when the user adds a new record
121 via a POST form, and your app returns them to the list of records.
122 If you use "forward", then you are still in the same request as the
124 original add record. The user might hit reload, expecting to refresh
125 the list of records. But in fact, reload will attempt to repost the
126 add record form. The user's browser might present a warning about
127 reposting the same data. The browser may refuse to redisplay the page,
128 due for caching reasons.
129 So in this case, it may make more sense to do a fresh HTTP redirect
131 back to the Browse list.
132
134 forward
135 Runs another run mode passing any parameters you supply. Returns the
136 output of the new run mode.
137 return $self->forward('run_mode_name', @run_mode_params);
139
141 Before the forwarded run mode is called, the "forward_prerun" hook is
142 called. You can use this hook to do any prep work that you want to do
143 before any new run mode gains control.
144 This is similar to CGI::Application's built in "cgiapp_prerun" method,
146 but it is called each time you call forward; not just the when your
147 application starts.
148 sub setup {
150 my $self = shift;
151 $self->add_callback('forward_prerun' => \&prepare_rm_stuff);
152 }
153 sub prepare_rm_stuff {
155 my $self = shift;
156 # do any necessary prep work here....
157 }
158 Note that your hooked method will only be called when you call forward.
160 If you never call "forward", the hook will not be called. In
161 particuar, the hook will not be called for your application's
162 "start_mode". For that, you still use "cgiapp_prerun".
163 If you want to have a method run for every run mode including the
165 "start_mode", then you can call the hook directly from "cgiapp_prerun".
166 sub setup {
168 my $self = shift;
169 $self->add_callback('forward_prerun' => \&prepare_rm_stuff);
170 }
171 sub cgiapp_prerun {
172 my $self = shift;
173 $self->prepare_rm_stuff;
174 }
175 sub prepare_rm_stuff {
177 my $self = shift;
178 # do any necessary prep work here....
179 }
180 Alternately, you can hook "cgiapp_prerun" to the "forward_prerun" hook:
182 sub setup {
184 my $self = shift;
185 $self->add_callback('forward_prerun' => \&cgiapp_prerun);
186 }
187 sub cgiapp_prerun {
188 my $self = shift;
189 # do any necessary prep work here....
190 }
191 This is a less flexible solution, since certain things that can be done
193 in "cgiapp_prerun" (like setting "prerun_mode") won't work when the
194 method is called from the "forward_prerun" hook.
195
197 Michael Graham, "<mag-perl@occamstoothbrush.com>"
198
200 Please report any bugs or feature requests to
201 "bug-cgi-application-plugin-forward@rt.cpan.org", or through the web
202 interface at <http://rt.cpan.org>. I will be notified, and then you'll
203 automatically be notified of progress on your bug as I make changes.
204
206 Thanks to Mark Stosberg for the idea and...well...the implementation as
207 well.
208
210 Copyright 2005 Michael Graham, All Rights Reserved.
211 This program is free software; you can redistribute it and/or modify it
213 under the same terms as Perl itself.
214perl v5.34.0 2022-01-2C0GI::Application::Plugin::Forward(3)