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1 | =head1 NAME |
2 | |
3 | Catalyst::Manual::Intro - Introduction to Catalyst |
4 | |
5 | =head1 DESCRIPTION |
6 | |
aa2b0d97 |
7 | This is a brief introduction toCatalyst. It explains the most important |
8 | features of how Catalyst works and shows how to get a simple application |
9 | up and running quickly. For an introduction (without code) to Catalyst |
10 | itself, and why you should be using it, see L<Catalyst::Manual::About>. |
fc7ec1d9 |
11 | |
12 | =head2 What is Catalyst? |
13 | |
129cfe74 |
14 | Catalyst is an elegant web application framework, extremely flexible yet |
e178a66a |
15 | extremely simple. It's similar to Ruby on Rails, Spring (Java) and |
16 | L<Maypole>, upon which it was originally based. |
fc7ec1d9 |
17 | |
18 | =head3 MVC |
19 | |
e178a66a |
20 | Catalyst follows the Model-View-Controller (MVC) design pattern, |
21 | allowing you to easily separate concerns, like content, presentation, |
22 | and flow control, into separate modules. This separation allows you to |
23 | modify code that handles one concern without affecting code that handles |
24 | the others. Catalyst promotes the re-use of existing Perl modules that |
25 | already handle common web application concerns well. |
fc7ec1d9 |
26 | |
e178a66a |
27 | Here's how the M, V, and C map to those concerns, with examples of |
28 | well-known Perl modules you may want to use for each. |
fc7ec1d9 |
29 | |
30 | =over 4 |
31 | |
4a6895ce |
32 | =item * B<Model> |
fc7ec1d9 |
33 | |
34 | Access and modify content (data). L<Class::DBI>, L<Plucene>, L<Net::LDAP>... |
35 | |
4a6895ce |
36 | =item * B<View> |
fc7ec1d9 |
37 | |
e178a66a |
38 | Present content to the user. L<Template Toolkit|Template>, |
39 | L<Mason|HTML::Mason>, L<HTML::Template>... |
fc7ec1d9 |
40 | |
4a6895ce |
41 | =item * B<Controller> |
fc7ec1d9 |
42 | |
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43 | Control the whole request phase, check parameters, dispatch actions, flow |
44 | control. Catalyst! |
fc7ec1d9 |
45 | |
46 | =back |
47 | |
26e73131 |
48 | If you're unfamiliar with MVC and design patterns, you may want to check |
49 | out the original book on the subject, I<Design Patterns>, by Gamma, |
50 | Helm, Johnson, and Vlissides, also known as the Gang of Four (GoF). You |
51 | can also just Google it. Many, many web application frameworks are |
52 | based on MVC, including all those listed above. |
fc7ec1d9 |
53 | |
54 | =head3 Flexibility |
55 | |
e178a66a |
56 | Catalyst is much more flexible than many other frameworks. We'll talk |
57 | more about this later, but rest assured you can use your favorite Perl |
58 | modules with Catalyst. |
fc7ec1d9 |
59 | |
60 | =over 4 |
61 | |
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62 | =item * B<Multiple Models, Views, and Controllers> |
fc7ec1d9 |
63 | |
e178a66a |
64 | To build a Catalyst application, you handle each type of concern inside |
65 | special modules called L</Components>. Often this code will be very |
66 | simple, just calling out to Perl modules like those listed above under |
67 | L</MVC>. Catalyst handles these components in a very flexible way. Use |
68 | as many Models, Views, and Controllers as you like, using as many |
69 | different Perl modules as you like, all in the same application. Want to |
70 | manipulate multiple databases, and retrieve some data via LDAP? No |
71 | problem. Want to present data from the same Model using L<Template |
72 | Toolkit|Template> and L<PDF::Template>? Easy. |
fc7ec1d9 |
73 | |
cda8d1ac |
74 | =item * B<Reuseable Components> |
fc7ec1d9 |
75 | |
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76 | Not only does Catalyst promote the re-use of already existing Perl |
77 | modules, it also allows you to re-use your Catalyst components in |
78 | multiple Catalyst applications. |
fc7ec1d9 |
79 | |
4a6895ce |
80 | =item * B<Unrestrained URL-to-Action Dispatching> |
fc7ec1d9 |
81 | |
e178a66a |
82 | Catalyst allows you to dispatch any URLs to any application L<Actions>, |
83 | even through regular expressions! Unlike most other frameworks, it |
84 | doesn't require mod_rewrite or class and method names in URLs. |
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85 | |
e178a66a |
86 | With Catalyst you register your actions and address them directly. For |
87 | example: |
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88 | |
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89 | sub hello : Global { |
fc7ec1d9 |
90 | my ( $self, $context ) = @_; |
66f6e959 |
91 | $context->response->body('Hello World!'); |
5a8ed4fe |
92 | } |
fc7ec1d9 |
93 | |
94 | Now http://localhost:3000/hello prints "Hello World!". |
95 | |
4a6895ce |
96 | =item * B<Support for CGI, mod_perl, Apache::Request> |
fc7ec1d9 |
97 | |
98 | Use L<Catalyst::Engine::Apache> or L<Catalyst::Engine::CGI>. |
99 | |
100 | =back |
101 | |
102 | =head3 Simplicity |
103 | |
e178a66a |
104 | The best part is that Catalyst implements all this flexibility in a very |
105 | simple way. |
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106 | |
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107 | =over 4 |
108 | |
4a6895ce |
109 | =item * B<Building Block Interface> |
fc7ec1d9 |
110 | |
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111 | Components interoperate very smoothly. For example, Catalyst |
112 | automatically makes a L<Context> object available to every |
113 | component. Via the context, you can access the request object, share |
114 | data between components, and control the flow of your |
115 | application. Building a Catalyst application feels a lot like snapping |
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116 | together toy building blocks, and everything just works. |
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117 | |
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118 | =item * B<Component Auto-Discovery> |
fc7ec1d9 |
119 | |
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120 | No need to C<use> all of your components. Catalyst automatically finds |
121 | and loads them. |
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122 | |
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123 | =item * B<Pre-Built Components for Popular Modules> |
fc7ec1d9 |
124 | |
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125 | See L<Catalyst::Model::CDBI> for L<Class::DBI>, or L<Catalyst::View::TT> |
126 | for L<Template Toolkit|Template>. |
fc7ec1d9 |
127 | |
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128 | =item * B<Built-in Test Framework> |
fc7ec1d9 |
129 | |
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130 | Catalyst comes with a built-in, lightweight http server and test |
131 | framework, making it easy to test applications from the command line. |
fc7ec1d9 |
132 | |
4a6895ce |
133 | =item * B<Helper Scripts> |
fc7ec1d9 |
134 | |
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135 | Catalyst provides helper scripts to quickly generate running starter |
136 | code for components and unit tests. See L<Catalyst::Helper>. |
fc7ec1d9 |
137 | |
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138 | =back |
139 | |
fc7ec1d9 |
140 | =head2 Quickstart |
141 | |
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142 | Here's how to install Catalyst and get a simple application up and |
143 | running, using the helper scripts described above. |
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144 | |
145 | =head3 Install |
146 | |
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147 | $ perl -MCPAN -e 'install Task::Catalyst' |
fc7ec1d9 |
148 | |
149 | =head3 Setup |
150 | |
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151 | $ catalyst.pl MyApp |
b33ed88c |
152 | # output omitted |
2feb6632 |
153 | $ cd MyApp |
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154 | $ script/myapp_create.pl controller Library::Login |
fc7ec1d9 |
155 | |
156 | =head3 Run |
157 | |
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158 | $ script/myapp_server.pl |
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159 | |
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160 | Now visit these locations with your favorite browser or user agent to see |
161 | Catalyst in action: |
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162 | |
163 | =over 4 |
164 | |
165 | =item http://localhost:3000/ |
166 | |
ac4a0ae0 |
167 | =item http://localhost:3000/library/login/ |
fc7ec1d9 |
168 | |
169 | =back |
170 | |
171 | Dead easy! |
172 | |
173 | =head2 How It Works |
174 | |
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175 | Let's see how Catalyst works, by taking a closer look at the components |
176 | and other parts of a Catalyst application. |
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177 | |
178 | =head3 Application Class |
179 | |
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180 | In addition to the Model, View, and Controller components, there's a |
181 | single class that represents your application itself. This is where you |
182 | configure your application, load plugins, define application-wide |
183 | actions, and extend Catalyst. |
fc7ec1d9 |
184 | |
185 | package MyApp; |
186 | |
187 | use strict; |
188 | use Catalyst qw/-Debug/; |
189 | |
190 | MyApp->config( |
191 | name => 'My Application', |
fc7ec1d9 |
192 | |
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193 | # You can put anything else you want in here: |
194 | my_configuration_variable => 'something', |
fc7ec1d9 |
195 | ); |
196 | |
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197 | sub default : Private { |
fc7ec1d9 |
198 | my ( $self, $context ) = @_; |
e178a66a |
199 | $context->response->body('Catalyst rocks!'); |
5a8ed4fe |
200 | } |
fc7ec1d9 |
201 | |
202 | 1; |
203 | |
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204 | For most applications, Catalyst requires you to define only one config |
205 | parameter: |
fc7ec1d9 |
206 | |
207 | =over 4 |
208 | |
4a6895ce |
209 | =item * B<name> |
fc7ec1d9 |
210 | |
211 | Name of your application. |
212 | |
fc7ec1d9 |
213 | =back |
214 | |
e178a66a |
215 | Optionally, you can specify a B<root> parameter for templates and static |
216 | data. If omitted, Catalyst will try to auto-detect the directory's |
217 | location. You can define as many parameters as you want for plugins or |
218 | whatever you need. You can access them anywhere in your application via |
219 | C<$context-E<gt>config-E<gt>{$param_name}>. |
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220 | |
221 | =head3 Context |
222 | |
e178a66a |
223 | Catalyst automatically blesses a Context object into your application |
224 | class and makes it available everywhere in your application. Use the |
225 | Context to directly interact with Catalyst and glue your L<Components> |
226 | together. For example, if you need to use the Context from within a |
227 | Template Toolkit template, it's already there: |
c42f5bbf |
228 | |
229 | <h1>Welcome to [% c.config.name %]!</h1> |
fc7ec1d9 |
230 | |
e178a66a |
231 | As illustrated in our URL-to-Action dispatching example, the Context is |
232 | always the second method parameter, behind the Component object |
233 | reference or class name itself. Previously we called it C<$context> for |
234 | clarity, but most Catalyst developers just call it C<$c>: |
fc7ec1d9 |
235 | |
e3dc9d78 |
236 | sub hello : Global { |
fc7ec1d9 |
237 | my ( $self, $c ) = @_; |
66f6e959 |
238 | $c->res->body('Hello World!'); |
5a8ed4fe |
239 | } |
fc7ec1d9 |
240 | |
241 | The Context contains several important objects: |
242 | |
243 | =over 4 |
244 | |
245 | =item * L<Catalyst::Request> |
246 | |
247 | $c->request |
248 | $c->req # alias |
249 | |
129cfe74 |
250 | The request object contains all kinds of request-specific information, like |
251 | query parameters, cookies, uploads, headers, and more. |
fc7ec1d9 |
252 | |
253 | $c->req->params->{foo}; |
254 | $c->req->cookies->{sessionid}; |
255 | $c->req->headers->content_type; |
256 | $c->req->base; |
257 | |
afdca3a3 |
258 | =item * L<Catalyst::Response> |
fc7ec1d9 |
259 | |
260 | $c->response |
261 | $c->res # alias |
262 | |
129cfe74 |
263 | The response is like the request, but contains just response-specific |
264 | information. |
fc7ec1d9 |
265 | |
66f6e959 |
266 | $c->res->body('Hello World'); |
fc7ec1d9 |
267 | $c->res->status(404); |
268 | $c->res->redirect('http://oook.de'); |
269 | |
270 | =item * L<Catalyst::Config> |
271 | |
272 | $c->config |
fc7ec1d9 |
273 | $c->config->root; |
274 | $c->config->name; |
275 | |
276 | =item * L<Catalyst::Log> |
277 | |
278 | $c->log |
279 | |
280 | $c->log->debug('Something happened'); |
281 | $c->log->info('Something you should know'); |
282 | |
4a6895ce |
283 | =item * B<Stash> |
fc7ec1d9 |
284 | |
285 | $c->stash |
fc7ec1d9 |
286 | $c->stash->{foo} = 'bar'; |
287 | |
288 | =back |
289 | |
129cfe74 |
290 | The last of these, the stash, is a universal hash for sharing data among |
291 | application components. For an example, we return to our 'hello' action: |
fc7ec1d9 |
292 | |
e3dc9d78 |
293 | sub hello : Global { |
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294 | my ( $self, $c ) = @_; |
295 | $c->stash->{message} = 'Hello World!'; |
4c6807d2 |
296 | $c->forward('show_message'); |
5a8ed4fe |
297 | } |
fc7ec1d9 |
298 | |
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299 | sub show_message : Private { |
5a8ed4fe |
300 | my ( $self, $c ) = @_; |
66f6e959 |
301 | $c->res->body( $c->stash->{message} ); |
5a8ed4fe |
302 | } |
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303 | |
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304 | Note that the stash should be used only for passing data in an |
305 | individual request cycle; it gets cleared at a new request. If you need |
306 | to maintain more persistent data, use a session. |
dd25a192 |
307 | |
fc7ec1d9 |
308 | =head3 Actions |
309 | |
e178a66a |
310 | A Catalyst controller is defined by its actions. An action is a sub with |
311 | a special attribute. You've already seen some examples of actions in |
312 | this document. The URL (for example http://localhost.3000/foo/bar) |
313 | consists of two parts, the base (http://localhost:3000/ in this example) |
314 | and the path (foo/bar). Please note that the trailing slash after the |
315 | hostname[:port] always belongs to base and not to the action. |
cda8d1ac |
316 | |
317 | Catalyst supports several types of actions: |
fc7ec1d9 |
318 | |
319 | =over 4 |
320 | |
4a6895ce |
321 | =item * B<Literal> |
fc7ec1d9 |
322 | |
e178a66a |
323 | package MyApp::Controller::My::Controller; |
f29c48dd |
324 | sub bar : Path('foo/bar') { } |
fc7ec1d9 |
325 | |
e178a66a |
326 | Literal C<Path> actions will act relative to their current |
327 | namespace. The above example matches only |
328 | http://localhost:3000/my/controller/foo/bar. If you start your path with |
329 | a forward slash, it will match from the root. Example: |
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330 | |
e178a66a |
331 | package MyApp::Controller::My::Controller; |
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332 | sub bar : Path('/foo/bar') { } |
333 | |
fc7ec1d9 |
334 | Matches only http://localhost:3000/foo/bar. |
335 | |
e178a66a |
336 | package MyApp::Controller::My::Controller; |
0cf56dbc |
337 | sub bar : Path { } |
338 | |
e178a66a |
339 | By leaving the C<Path> definition empty, it will match on the namespace |
340 | root. The above code matches http://localhost:3000/my/controller. |
0cf56dbc |
341 | |
4a6895ce |
342 | =item * B<Regex> |
fc7ec1d9 |
343 | |
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344 | sub bar : Regex('^item(\d+)/order(\d+)$') { } |
fc7ec1d9 |
345 | |
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346 | Matches any URL that matches the pattern in the action key, e.g. |
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347 | http://localhost:3000/item23/order42. The '' around the regexp is |
348 | optional, but perltidy likes it. :) |
b33ed88c |
349 | |
e178a66a |
350 | Regex matches act globally, i.e. without reference to the namespace from |
351 | which it is called, so that a C<bar> method in the |
352 | C<MyApp::Controller::Catalog::Order::Process> namespace won't match any |
353 | form of C<bar>, C<Catalog>, C<Order>, or C<Process> unless you |
354 | explicitly put this in the regex. To achieve the above, you should |
355 | consider using a C<LocalRegex> action. |
66f6e959 |
356 | |
357 | =item * B<LocalRegex> |
358 | |
359 | sub bar : LocalRegex('^widget(\d+)$') { } |
fc7ec1d9 |
360 | |
66f6e959 |
361 | LocalRegex actions act locally. If you were to use C<bar> in |
0cf56dbc |
362 | C<MyApp::Controller::Catalog>, the above example would match urls like |
363 | http://localhost:3000/catalog/widget23. |
364 | |
e178a66a |
365 | If you omit the "C<^>" from your regex, then it will match any depth |
366 | from the controller and not immediately off of the controller name. The |
367 | following example differs from the above code in that it will match |
0cf56dbc |
368 | http://localhost:3000/catalog/foo/widget23 as well. |
369 | |
370 | package MyApp::Controller::Catalog; |
371 | sub bar : LocalRegex('widget(\d+)$') { } |
66f6e959 |
372 | |
e178a66a |
373 | For both LocalRegex and Regex actions, if you use capturing parentheses |
374 | to extract values within the matching URL, those values are available in |
375 | the C<$c-E<gt>req-E<gt>snippets> array. In the above example, "widget23" |
376 | would capture "23" in the above example, and |
377 | C<$c-E<gt>req-E<gt>snippets-E<gt>[0]> would be "23". If you want to pass |
378 | arguments at the end of your URL, you must use regex action keys. See |
379 | L</URL Path Handling> below. |
fc7ec1d9 |
380 | |
72d9bfc7 |
381 | =item * B<Top-level> |
cda8d1ac |
382 | |
383 | package MyApp; |
384 | sub foo : Global { } |
385 | |
b33ed88c |
386 | Matches http://localhost:3000/foo. The function name is mapped directly |
387 | to the application base. |
cda8d1ac |
388 | |
4a6895ce |
389 | =item * B<Namespace-Prefixed> |
fc7ec1d9 |
390 | |
e178a66a |
391 | package MyApp::Controller::My::Controller; |
e3dc9d78 |
392 | sub foo : Local { } |
fc7ec1d9 |
393 | |
cda8d1ac |
394 | Matches http://localhost:3000/my/controller/foo. |
fc7ec1d9 |
395 | |
129cfe74 |
396 | This action type indicates that the matching URL must be prefixed with a |
e178a66a |
397 | modified form of the component's class (package) name. This modified |
398 | class name excludes the parts that have a pre-defined meaning in |
399 | Catalyst ("MyApp::Controller" in the above example), replaces "::" with |
400 | "/", and converts the name to lower case. See L</Components> for a full |
401 | explanation of the pre-defined meaning of Catalyst component class |
402 | names. |
fc7ec1d9 |
403 | |
4a6895ce |
404 | =item * B<Private> |
fc7ec1d9 |
405 | |
5a8ed4fe |
406 | sub foo : Private { } |
fc7ec1d9 |
407 | |
e178a66a |
408 | Matches no URL, and cannot be executed by requesting a URL that |
409 | corresponds to the action key. Private actions can be executed only |
410 | inside a Catalyst application, by calling the C<forward> method: |
fc7ec1d9 |
411 | |
5a8ed4fe |
412 | $c->forward('foo'); |
fc7ec1d9 |
413 | |
129cfe74 |
414 | See L</Flow Control> for a full explanation of C<forward>. Note that, as |
fc9c8698 |
415 | discussed there, when forwarding from another component, you must use |
416 | the absolute path to the method, so that a private C<bar> method in your |
417 | C<MyApp::Controller::Catalog::Order::Process> controller must, if called |
418 | from elsewhere, be reached with |
419 | C<$c-E<gt>forward('/catalog/order/process/bar')>. |
fc7ec1d9 |
420 | |
421 | =back |
422 | |
b33ed88c |
423 | B<Note:> After seeing these examples, you probably wonder what the point |
424 | is of defining names for regex and path actions. Actually, every public |
425 | action is also a private one, so you have one unified way of addressing |
426 | components in your C<forward>s. |
cda8d1ac |
427 | |
72d9bfc7 |
428 | =head4 Built-in Private Actions |
fc7ec1d9 |
429 | |
fc9c8698 |
430 | In response to specific application states, Catalyst will automatically |
431 | call these built-in private actions in your application class: |
fc7ec1d9 |
432 | |
433 | =over 4 |
434 | |
cda8d1ac |
435 | =item * B<default : Private> |
fc7ec1d9 |
436 | |
fc9c8698 |
437 | Called when no other action matches. Could be used, for example, for |
438 | displaying a generic frontpage for the main app, or an error page for |
439 | individual controllers. |
fc7ec1d9 |
440 | |
0cf56dbc |
441 | If C<default> isn't acting how you would expect, look at using a |
e178a66a |
442 | L<Literal> C<Path> action (with an empty path string). The difference is |
443 | that C<Path> takes arguments relative from the namespace and C<default> |
444 | I<always> takes arguments relative from the root, regardless of what |
445 | controller it's in. |
0cf56dbc |
446 | |
66f6e959 |
447 | =item * B<index : Private> |
448 | |
449 | C<index> is much like C<default> except that it takes no arguments |
e178a66a |
450 | and it is weighted slightly higher in the matching process. It is |
451 | useful as a static entry point to a controller, e.g. to have a static |
61a9002d |
452 | welcome page. Note that it's also weighted higher than Path. |
66f6e959 |
453 | |
cda8d1ac |
454 | =item * B<begin : Private> |
fc7ec1d9 |
455 | |
fc9c8698 |
456 | Called at the beginning of a request, before any matching actions are |
457 | called. |
fc7ec1d9 |
458 | |
cda8d1ac |
459 | =item * B<end : Private> |
4a6895ce |
460 | |
fc7ec1d9 |
461 | Called at the end of a request, after all matching actions are called. |
462 | |
fc9c8698 |
463 | =back |
464 | |
6b10c72b |
465 | =head4 Built-in actions in controllers/autochaining |
fc7ec1d9 |
466 | |
e178a66a |
467 | Package MyApp::Controller::Foo; |
cda8d1ac |
468 | sub begin : Private { } |
5a8ed4fe |
469 | sub default : Private { } |
eff5f524 |
470 | sub auto : Private { } |
fc7ec1d9 |
471 | |
fc9c8698 |
472 | You can define built-in private actions within your controllers as |
473 | well. The actions will override the ones in less-specific controllers, |
474 | or your application class. In other words, for each of the three |
475 | built-in private actions, only one will be run in any request |
e178a66a |
476 | cycle. Thus, if C<MyApp::Controller::Catalog::begin> exists, it will be |
477 | run in place of C<MyApp::begin> if you're in the C<catalog> namespace, |
478 | and C<MyApp::Controller::Catalog::Order::begin> would override this in |
479 | turn. |
fc9c8698 |
480 | |
eff5f524 |
481 | In addition to the normal built-in actions, you have a special action |
482 | for making chains, C<auto>. Such C<auto> actions will be run after any |
fc9c8698 |
483 | C<begin>, but before your action is processed. Unlike the other |
eff5f524 |
484 | built-ins, C<auto> actions I<do not> override each other; they will be |
485 | called in turn, starting with the application class and going through to |
486 | the I<most> specific class. I<This is the reverse of the order in which |
487 | the normal built-ins override each other>. |
fc9c8698 |
488 | |
489 | Here are some examples of the order in which the various built-ins |
490 | would be called: |
cda8d1ac |
491 | |
492 | =over 4 |
493 | |
fc9c8698 |
494 | =item for a request for C</foo/foo> |
cda8d1ac |
495 | |
496 | MyApp::begin |
80ef2e6d |
497 | MyApp::auto |
e178a66a |
498 | MyApp::Controller::Foo::default # in the absence of MyApp::Controller::Foo::Foo |
cda8d1ac |
499 | MyApp::end |
500 | |
fc9c8698 |
501 | =item for a request for C</foo/bar/foo> |
cda8d1ac |
502 | |
e178a66a |
503 | MyApp::Controller::Foo::Bar::begin |
80ef2e6d |
504 | MyApp::auto |
e178a66a |
505 | MyApp::Controller::Foo::auto |
506 | MyApp::Controller::Foo::Bar::auto |
507 | MyApp::Controller::Foo::Bar::default # for MyApp::Controller::Foo::Bar::foo |
508 | MyApp::Controller::Foo::Bar::end |
80ef2e6d |
509 | |
510 | =back |
511 | |
fc9c8698 |
512 | The C<auto> action is also distinguished by the fact that you can break |
513 | out of the processing chain by returning 0. If an C<auto> action returns |
514 | 0, any remaining actions will be skipped, except for C<end>. So, for the |
515 | request above, if the first auto returns false, the chain would look |
516 | like this: |
80ef2e6d |
517 | |
518 | =over 4 |
519 | |
fc9c8698 |
520 | =item for a request for C</foo/bar/foo> where first C<auto> returns |
521 | false |
80ef2e6d |
522 | |
e178a66a |
523 | MyApp::Controller::Foo::Bar::begin |
80ef2e6d |
524 | MyApp::auto |
e178a66a |
525 | MyApp::Controller::Foo::Bar::end |
cda8d1ac |
526 | |
527 | =back |
4a6895ce |
528 | |
fc9c8698 |
529 | An example of why one might use this is an authentication action: you |
530 | could set up a C<auto> action to handle authentication in your |
531 | application class (which will always be called first), and if |
532 | authentication fails, returning 0 would skip any remaining methods |
533 | for that URL. |
03805733 |
534 | |
fc9c8698 |
535 | B<Note:> Looking at it another way, C<auto> actions have to return a |
536 | true value to continue processing! You can also C<die> in the autochain |
537 | action; in that case, the request will go straight to the finalize |
538 | stage, without processing further actions. |
03805733 |
539 | |
6b10c72b |
540 | =head4 URL Path Handling |
4a6895ce |
541 | |
70d5ae49 |
542 | You can pass variable arguments as part of the URL path, separated with |
543 | forward slashes (/). If the action is a Regex or LocalRegex, the '$' anchor |
544 | must be used. For example, suppose you want to handle C</foo/$bar/$baz>, |
545 | where C<$bar> and C<$baz> may vary: |
4a6895ce |
546 | |
cda8d1ac |
547 | sub foo : Regex('^foo$') { my ($self, $context, $bar, $baz) = @_; } |
4a6895ce |
548 | |
fc9c8698 |
549 | But what if you also defined actions for C</foo/boo> and C</foo/boo/hoo>? |
4a6895ce |
550 | |
f29c48dd |
551 | sub boo : Path('foo/boo') { .. } |
552 | sub hoo : Path('foo/boo/hoo') { .. } |
4a6895ce |
553 | |
554 | Catalyst matches actions in most specific to least specific order: |
555 | |
556 | /foo/boo/hoo |
557 | /foo/boo |
fc9c8698 |
558 | /foo # might be /foo/bar/baz but won't be /foo/boo/hoo |
4a6895ce |
559 | |
fc9c8698 |
560 | So Catalyst would never mistakenly dispatch the first two URLs to the |
561 | '^foo$' action. |
fc7ec1d9 |
562 | |
70d5ae49 |
563 | If a Regex or LocalRegex action doesn't use the '$' anchor, the action will |
564 | still match a URL containing arguments, however the arguments won't be |
565 | available via C<@_>. |
566 | |
6b10c72b |
567 | =head4 Parameter Processing |
2ef2fb0f |
568 | |
fc9c8698 |
569 | Parameters passed in the URL query string are handled with methods in |
570 | the L<Catalyst::Request> class. The C<param> method is functionally |
571 | equivalent to the C<param> method of C<CGI.pm> and can be used in |
572 | modules that require this. |
2ef2fb0f |
573 | |
574 | # http://localhost:3000/catalog/view/?category=hardware&page=3 |
575 | my $category = $c->req->param('category'); |
576 | my $current_page = $c->req->param('page') || 1; |
577 | |
578 | # multiple values for single parameter name |
579 | my @values = $c->req->param('scrolling_list'); |
580 | |
581 | # DFV requires a CGI.pm-like input hash |
582 | my $results = Data::FormValidator->check($c->req->params, \%dfv_profile); |
583 | |
fc7ec1d9 |
584 | =head3 Flow Control |
585 | |
d08ced28 |
586 | You control the application flow with the C<forward> method, which |
587 | accepts the key of an action to execute. This can be an action in the |
588 | same or another Catalyst controller, or a Class name, optionally |
589 | followed by a method name. After a C<forward>, the control flow will |
590 | return to the method from which the C<forward> was issued. |
591 | |
592 | A C<forward> is similar to a method call. The main differences are that |
593 | it wraps the call in an C<eval> to allow exception handling; it |
594 | automatically passes along the context object (C<$c> or C<$context>); |
595 | and it allows profiling of each call (displayed in the log with |
596 | debugging enabled). |
fc7ec1d9 |
597 | |
e3dc9d78 |
598 | sub hello : Global { |
5a8ed4fe |
599 | my ( $self, $c ) = @_; |
600 | $c->stash->{message} = 'Hello World!'; |
d08ced28 |
601 | $c->forward('check_message'); # $c is automatically included |
5a8ed4fe |
602 | } |
fc7ec1d9 |
603 | |
4c6807d2 |
604 | sub check_message : Private { |
5a8ed4fe |
605 | my ( $self, $c ) = @_; |
606 | return unless $c->stash->{message}; |
4c6807d2 |
607 | $c->forward('show_message'); |
5a8ed4fe |
608 | } |
fc7ec1d9 |
609 | |
4c6807d2 |
610 | sub show_message : Private { |
5a8ed4fe |
611 | my ( $self, $c ) = @_; |
66f6e959 |
612 | $c->res->body( $c->stash->{message} ); |
5a8ed4fe |
613 | } |
3323f920 |
614 | |
d08ced28 |
615 | A C<forward> does not create a new request, so your request |
616 | object (C<$c-E<gt>req>) will remain unchanged. This is a |
617 | key difference between using C<forward> and issuing a |
618 | redirect. |
3323f920 |
619 | |
d08ced28 |
620 | You can pass new arguments to a C<forward> by adding them |
621 | in an anonymous array. In this case C<$c-E<gt>req-E<gt>args> |
622 | will be changed for the duration of the C<forward> only; upon |
623 | return, the original value of C<$c-E<gt>req-E<gt>args> will |
624 | be reset. |
3323f920 |
625 | |
626 | sub hello : Global { |
627 | my ( $self, $c ) = @_; |
628 | $c->stash->{message} = 'Hello World!'; |
d08ced28 |
629 | $c->forward('check_message',[qw/test1/]); |
630 | # now $c->req->args is back to what it was before |
3323f920 |
631 | } |
632 | |
d08ced28 |
633 | sub check_message : Private { |
634 | my ( $self, $c ) = @_; |
635 | my $first_argument = $c->req->args[0]; # now = 'test1' |
636 | # do something... |
637 | } |
cda8d1ac |
638 | |
d08ced28 |
639 | As you can see from these examples, you can just use the method name as |
640 | long as you are referring to methods in the same controller. If you want |
641 | to forward to a method in another controller, or the main application, |
642 | you will have to refer to the method by absolute path. |
cda8d1ac |
643 | |
644 | $c->forward('/my/controller/action'); |
d08ced28 |
645 | $c->forward('/default'); # calls default in main application |
fc7ec1d9 |
646 | |
d08ced28 |
647 | Here are some examples of how to forward to classes and methods. |
fc7ec1d9 |
648 | |
e3dc9d78 |
649 | sub hello : Global { |
5a8ed4fe |
650 | my ( $self, $c ) = @_; |
e178a66a |
651 | $c->forward(qw/MyApp::Model::Hello say_hello/); |
5a8ed4fe |
652 | } |
fc7ec1d9 |
653 | |
e3dc9d78 |
654 | sub bye : Global { |
5a8ed4fe |
655 | my ( $self, $c ) = @_; |
e178a66a |
656 | $c->forward('MyApp::Model::Hello'); # no method: will try 'process' |
5a8ed4fe |
657 | } |
fc7ec1d9 |
658 | |
e178a66a |
659 | package MyApp::Model::Hello; |
fc7ec1d9 |
660 | |
661 | sub say_hello { |
662 | my ( $self, $c ) = @_; |
66f6e959 |
663 | $c->res->body('Hello World!'); |
fc7ec1d9 |
664 | } |
665 | |
666 | sub process { |
667 | my ( $self, $c ) = @_; |
66f6e959 |
668 | $c->res->body('Goodbye World!'); |
fc7ec1d9 |
669 | } |
670 | |
d08ced28 |
671 | Note that C<forward> returns to the calling action and continues |
13436c14 |
672 | processing after the action finishes. If you want all further processing |
673 | in the calling action to stop, use C<detach> instead, which will execute |
674 | the C<detach>ed action and not return to the calling sub. In both cases, |
675 | Catalyst will automatically try to call process() if you omit the |
676 | method. |
fc7ec1d9 |
677 | |
678 | =head3 Components |
679 | |
129cfe74 |
680 | Catalyst has an uncommonly flexible component system. You can define as many |
681 | L<Models>, L<Views>, and L<Controllers> as you like. |
fc7ec1d9 |
682 | |
129cfe74 |
683 | All components must inherit from L<Catalyst::Base>, which provides a simple |
684 | class structure and some common class methods like C<config> and C<new> |
685 | (constructor). |
fc7ec1d9 |
686 | |
e178a66a |
687 | package MyApp::Controller::Catalog; |
fc7ec1d9 |
688 | |
689 | use strict; |
690 | use base 'Catalyst::Base'; |
691 | |
692 | __PACKAGE__->config( foo => 'bar' ); |
693 | |
694 | 1; |
695 | |
6b10c72b |
696 | You don't have to C<use> or otherwise register Models, Views, and |
697 | Controllers. Catalyst automatically discovers and instantiates them |
698 | when you call C<setup> in the main application. All you need to do is |
699 | put them in directories named for each Component type. Notice that you |
700 | can use some very terse aliases for each one. |
fc7ec1d9 |
701 | |
702 | =over 4 |
703 | |
4a6895ce |
704 | =item * B<MyApp/Model/> |
fc7ec1d9 |
705 | |
4a6895ce |
706 | =item * B<MyApp/M/> |
fc7ec1d9 |
707 | |
4a6895ce |
708 | =item * B<MyApp/View/> |
fc7ec1d9 |
709 | |
4a6895ce |
710 | =item * B<MyApp/V/> |
fc7ec1d9 |
711 | |
4a6895ce |
712 | =item * B<MyApp/Controller/> |
fc7ec1d9 |
713 | |
4a6895ce |
714 | =item * B<MyApp/C/> |
fc7ec1d9 |
715 | |
716 | =back |
717 | |
718 | =head4 Views |
719 | |
129cfe74 |
720 | To show how to define views, we'll use an already-existing base class for the |
721 | L<Template Toolkit|Template>, L<Catalyst::View::TT>. All we need to do is |
722 | inherit from this class: |
fc7ec1d9 |
723 | |
e178a66a |
724 | package MyApp::View::TT; |
fc7ec1d9 |
725 | |
726 | use strict; |
727 | use base 'Catalyst::View::TT'; |
728 | |
729 | 1; |
730 | |
b33ed88c |
731 | (You can also generate this automatically by using the helper script: |
732 | |
733 | script/myapp_create.pl view TT TT |
734 | |
fb9257c1 |
735 | where the first C<TT> tells the script that the name of the view should |
736 | be C<TT>, and the second that it should be a Template Toolkit view.) |
b33ed88c |
737 | |
129cfe74 |
738 | This gives us a process() method and we can now just do |
e178a66a |
739 | $c->forward('MyApp::View::TT') to render our templates. The base class |
740 | makes process() implicit, so we don't have to say |
741 | C<$c-E<gt>forward(qw/MyApp::View::TT process/)>. |
fc7ec1d9 |
742 | |
e3dc9d78 |
743 | sub hello : Global { |
5a8ed4fe |
744 | my ( $self, $c ) = @_; |
745 | $c->stash->{template} = 'hello.tt'; |
746 | } |
fc7ec1d9 |
747 | |
5a8ed4fe |
748 | sub end : Private { |
749 | my ( $self, $c ) = @_; |
e178a66a |
750 | $c->forward('MyApp::View::TT'); |
5a8ed4fe |
751 | } |
fc7ec1d9 |
752 | |
6b10c72b |
753 | You normally render templates at the end of a request, so it's a perfect |
754 | use for the global C<end> action. |
fc7ec1d9 |
755 | |
129cfe74 |
756 | Also, be sure to put the template under the directory specified in |
6b10c72b |
757 | C<$c-E<gt>config-E<gt>{root}>, or you'll be forced to look at our |
758 | eyecandy debug screen. ;) |
fc7ec1d9 |
759 | |
760 | =head4 Models |
761 | |
e178a66a |
762 | To show how to define models, again we'll use an already-existing base |
763 | class, this time for L<Class::DBI>: L<Catalyst::Model::CDBI>. |
fc7ec1d9 |
764 | |
765 | But first, we need a database. |
766 | |
767 | -- myapp.sql |
768 | CREATE TABLE foo ( |
769 | id INTEGER PRIMARY KEY, |
770 | data TEXT |
771 | ); |
772 | |
773 | CREATE TABLE bar ( |
774 | id INTEGER PRIMARY KEY, |
775 | foo INTEGER REFERENCES foo, |
776 | data TEXT |
777 | ); |
778 | |
779 | INSERT INTO foo (data) VALUES ('TEST!'); |
780 | |
781 | |
782 | % sqlite /tmp/myapp.db < myapp.sql |
783 | |
784 | Now we can create a CDBI component for this database. |
785 | |
e178a66a |
786 | package MyApp::Model::CDBI; |
fc7ec1d9 |
787 | |
788 | use strict; |
789 | use base 'Catalyst::Model::CDBI'; |
790 | |
791 | __PACKAGE__->config( |
792 | dsn => 'dbi:SQLite:/tmp/myapp.db', |
793 | relationships => 1 |
794 | ); |
795 | |
796 | 1; |
797 | |
e178a66a |
798 | Catalyst automatically loads table layouts and relationships. Use the |
799 | stash to pass data to your templates. |
fc7ec1d9 |
800 | |
801 | package MyApp; |
802 | |
803 | use strict; |
804 | use Catalyst '-Debug'; |
805 | |
806 | __PACKAGE__->config( |
807 | name => 'My Application', |
808 | root => '/home/joeuser/myapp/root' |
809 | ); |
cda8d1ac |
810 | |
811 | __PACKAGE__->setup; |
fc7ec1d9 |
812 | |
5a8ed4fe |
813 | sub end : Private { |
814 | my ( $self, $c ) = @_; |
815 | $c->stash->{template} ||= 'index.tt'; |
e178a66a |
816 | $c->forward('MyApp::View::TT'); |
5a8ed4fe |
817 | } |
fc7ec1d9 |
818 | |
e3dc9d78 |
819 | sub view : Global { |
5a8ed4fe |
820 | my ( $self, $c, $id ) = @_; |
e178a66a |
821 | $c->stash->{item} = MyApp::Model::CDBI::Foo->retrieve($id); |
5a8ed4fe |
822 | } |
fc7ec1d9 |
823 | |
824 | 1; |
825 | |
6b10c72b |
826 | # Then, in a TT template: |
fc7ec1d9 |
827 | The id is [% item.data %] |
828 | |
6b10c72b |
829 | Models do not have to be part of your Catalyst application; you |
830 | can always call an outside module that serves as your Model: |
831 | |
832 | # in a Controller |
833 | sub list : Local { |
834 | my ( $self, $c ) = @_; |
835 | $c->stash->{template} = 'list.tt'; |
836 | use Some::Outside::CDBI::Module; |
837 | my @records = Some::Outside::CDBI::Module->retrieve_all; |
838 | $c->stash->{records} = \@records; |
839 | } |
840 | |
841 | But by using a Model that is part of your Catalyst application, you gain |
842 | several things: you don't have to C<use> each component, Catalyst will |
843 | find and load it automatically at compile-time; you can C<forward> to |
26e73131 |
844 | the module, which can only be done to Catalyst components; and only |
6b10c72b |
845 | Catalyst components can be fetched with |
e178a66a |
846 | C<$c-E<gt>model('SomeModel')>. |
6b10c72b |
847 | |
848 | Happily, since many people have existing Model classes that they |
849 | would like to use with Catalyst (or, conversely, they want to |
850 | write Catalyst models that can be used outside of Catalyst, e.g. |
851 | in a cron job), it's trivial to write a simple component in |
852 | Catalyst that slurps in an outside Model: |
853 | |
e178a66a |
854 | package MyApp::Model::Catalog; |
6b10c72b |
855 | use base qw/Catalyst::Base Some::Other::CDBI::Module::Catalog/; |
856 | 1; |
857 | |
858 | and that's it! Now C<Some::Other::CDBI::Module::Catalog> is part of your |
e178a66a |
859 | Cat app as C<MyApp::Model::Catalog>. |
6b10c72b |
860 | |
fc7ec1d9 |
861 | =head4 Controllers |
862 | |
129cfe74 |
863 | Multiple controllers are a good way to separate logical domains of your |
864 | application. |
fc7ec1d9 |
865 | |
e178a66a |
866 | package MyApp::Controller::Login; |
fc7ec1d9 |
867 | |
fb9257c1 |
868 | sub sign-in : Local { } |
869 | sub new-password : Local { } |
870 | sub sign-out : Local { } |
fc7ec1d9 |
871 | |
e178a66a |
872 | package MyApp::Controller::Catalog; |
fc7ec1d9 |
873 | |
e3dc9d78 |
874 | sub view : Local { } |
875 | sub list : Local { } |
fc7ec1d9 |
876 | |
e178a66a |
877 | package MyApp::Controller::Cart; |
fc7ec1d9 |
878 | |
e3dc9d78 |
879 | sub add : Local { } |
880 | sub update : Local { } |
881 | sub order : Local { } |
fc7ec1d9 |
882 | |
883 | =head3 Testing |
884 | |
e178a66a |
885 | Catalyst has a built-in http server for testing! (Later, you can easily |
886 | use a more powerful server, e.g. Apache/mod_perl, in a production |
887 | environment.) |
fc7ec1d9 |
888 | |
889 | Start your application on the command line... |
890 | |
b33ed88c |
891 | script/myapp_server.pl |
fc7ec1d9 |
892 | |
893 | ...then visit http://localhost:3000/ in a browser to view the output. |
894 | |
895 | You can also do it all from the command line: |
896 | |
b33ed88c |
897 | script/myapp_test.pl http://localhost/ |
fc7ec1d9 |
898 | |
899 | Have fun! |
900 | |
3cb1db8c |
901 | =head1 SUPPORT |
902 | |
903 | IRC: |
904 | |
905 | Join #catalyst on irc.perl.org. |
906 | |
72d9bfc7 |
907 | Mailing-lists: |
3cb1db8c |
908 | |
909 | http://lists.rawmode.org/mailman/listinfo/catalyst |
910 | http://lists.rawmode.org/mailman/listinfo/catalyst-dev |
911 | |
fc7ec1d9 |
912 | =head1 AUTHOR |
913 | |
cda8d1ac |
914 | Sebastian Riedel, C<sri@oook.de> |
915 | David Naughton, C<naughton@umn.edu> |
916 | Marcus Ramberg, C<mramberg@cpan.org> |
f531dd37 |
917 | Jesse Sheidlower, C<jester@panix.com> |
129cfe74 |
918 | Danijel Milicevic, C<me@danijel.de> |
fc7ec1d9 |
919 | |
920 | =head1 COPYRIGHT |
921 | |
aa2b0d97 |
922 | This program is free software, you can redistribute it and/or modify it |
923 | under the same terms as Perl itself. |