Commit | Line | Data |
d442cc9f |
1 | =head1 NAME |
2 | |
3ab6187c |
3 | Catalyst::Manual::Tutorial::02_CatalystBasics - Catalyst Tutorial - Chapter 2: Catalyst Application Development Basics |
d442cc9f |
4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
4b4d3884 |
8 | This is B<Chapter 2 of 10> for the Catalyst tutorial. |
d442cc9f |
9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
3ab6187c |
16 | L<Introduction|Catalyst::Manual::Tutorial::01_Intro> |
d442cc9f |
17 | |
18 | =item 2 |
19 | |
3ab6187c |
20 | B<02_Catalyst Basics> |
d442cc9f |
21 | |
22 | =item 3 |
23 | |
3ab6187c |
24 | L<More Catalyst Basics|Catalyst::Manual::Tutorial::03_MoreCatalystBasics> |
d442cc9f |
25 | |
26 | =item 4 |
27 | |
3ab6187c |
28 | L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD> |
d442cc9f |
29 | |
30 | =item 5 |
31 | |
3ab6187c |
32 | L<Authentication|Catalyst::Manual::Tutorial::05_Authentication> |
d442cc9f |
33 | |
34 | =item 6 |
35 | |
3ab6187c |
36 | L<Authorization|Catalyst::Manual::Tutorial::06_Authorization> |
d442cc9f |
37 | |
38 | =item 7 |
39 | |
3ab6187c |
40 | L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> |
d442cc9f |
41 | |
42 | =item 8 |
43 | |
3ab6187c |
44 | L<Testing|Catalyst::Manual::Tutorial::08_Testing> |
d442cc9f |
45 | |
46 | =item 9 |
47 | |
3ab6187c |
48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD> |
3533daff |
49 | |
50 | =item 10 |
51 | |
3ab6187c |
52 | L<Appendices|Catalyst::Manual::Tutorial::10_Appendices> |
d442cc9f |
53 | |
54 | =back |
55 | |
56 | |
57 | =head1 DESCRIPTION |
58 | |
4b4d3884 |
59 | In this chapter of the tutorial, we will create a very basic Catalyst |
60 | web application, demonstrating a number of powerful capabilities, such |
61 | as: |
d442cc9f |
62 | |
63 | =over 4 |
64 | |
65 | =item * Helper Scripts |
66 | |
67 | Catalyst helper scripts that can be used to rapidly bootstrap the |
68 | skeletal structure of an application. |
69 | |
70 | =item * MVC |
71 | |
72 | Model/View/Controller (MVC) provides an architecture that facilitates a |
73 | clean "separation of control" between the different portions of your |
74 | application. Given that many other documents cover this subject in |
75 | detail, MVC will not be discussed in depth here (for an excellent |
76 | introduction to MVC and general Catalyst concepts, please see |
865d3efb |
77 | L<Catalyst::Manual::About|Catalyst::Manual::About>). In short: |
d442cc9f |
78 | |
79 | =over 4 |
80 | |
81 | =item * Model |
82 | |
83 | The model usually represents a data store. In most applications, the |
84 | model equates to the objects that are created from and saved to your SQL |
85 | database. |
86 | |
87 | =item * View |
88 | |
89 | The view takes model objects and renders them into something for the end |
90 | user to look at. Normally this involves a template-generation tool that |
91 | creates HTML for the user's web browser, but it could easily be code |
865d3efb |
92 | that generates other forms such as PDF documents, e-mails, spreadsheets, |
93 | or even "behind the scenes" formats such as XML and JSON. |
d442cc9f |
94 | |
95 | =item * Controller |
96 | |
97 | As suggested by its name, the controller takes user requests and routes |
98 | them to the necessary model and view. |
99 | |
100 | =back |
101 | |
102 | =item * ORM |
103 | |
104 | The use of Object-Relational Mapping (ORM) technology for database |
105 | access. Specifically, ORM provides an automated and standardized means |
106 | to persist and restore objects to/from a relational database. |
107 | |
108 | =back |
109 | |
110 | You can checkout the source code for this example from the catalyst |
111 | subversion repository as per the instructions in |
3ab6187c |
112 | L<Catalyst::Manual::Tutorial::01_Intro|Catalyst::Manual::Tutorial::01_Intro>. |
d442cc9f |
113 | |
3533daff |
114 | |
d442cc9f |
115 | =head1 CREATE A CATALYST PROJECT |
116 | |
3533daff |
117 | Catalyst provides a number of helper scripts that can be used to |
118 | quickly flesh out the basic structure of your application. All |
119 | Catalyst projects begin with the C<catalyst.pl> helper (see |
120 | L<Catalyst::Helper|Catalyst::Helper> for more information on helpers). |
121 | Also note that as of Catalyst 5.7000, you will not have the helper |
122 | scripts unless you install both L<Catalyst::Runtime|Catalyst::Runtime> |
123 | and L<Catalyst::Devel|Catalyst::Devel>. |
124 | |
4b4d3884 |
125 | In this first chapter of the tutorial, use the Catalyst C<catalyst.pl> |
126 | script to initialize the framework for an application called C<Hello>: |
3533daff |
127 | |
128 | $ catalyst.pl Hello |
129 | created "Hello" |
130 | created "Hello/script" |
131 | created "Hello/lib" |
132 | created "Hello/root" |
d442cc9f |
133 | ... |
3533daff |
134 | created "Hello/script/hello_create.pl" |
135 | $ cd Hello |
d442cc9f |
136 | |
137 | The C<catalyst.pl> helper script will display the names of the |
3533daff |
138 | directories and files it creates: |
139 | |
140 | Changes # Record of application changes |
865d3efb |
141 | lib # Lib directory for your app's Perl modules |
142 | Hello # Application main code directory |
3533daff |
143 | Controller # Directory for Controller modules |
144 | Model # Directory for Models |
145 | View # Directory for Views |
146 | Hello.pm # Base application module |
147 | Makefile.PL # Makefile to build application |
45d511e0 |
148 | hello.conf # Application configuration file |
3533daff |
149 | README # README file |
150 | root # Equiv of htdocs, dir for templates, css, javascript |
151 | favicon.ico |
152 | static # Directory for static files |
153 | images # Directory for image files used in welcome screen |
154 | script # Directory for Perl scripts |
155 | hello_cgi.pl # To run your app as a cgi (not recommended) |
156 | hello_create.pl # To create models, views, controllers |
157 | hello_fastcgi.pl # To run app as a fastcgi program |
158 | hello_server.pl # The normal development server |
159 | hello_test.pl # Test your app from the command line |
160 | t # Directory for tests |
161 | 01app.t # Test scaffold |
162 | 02pod.t |
163 | 03podcoverage.t |
164 | |
165 | |
166 | Catalyst will "auto-discover" modules in the Controller, Model, and |
167 | View directories. When you use the hello_create.pl script it will |
168 | create Perl module scaffolds in those directories, plus test files in |
169 | the "t" directory. The default location for templates is in the "root" |
170 | directory. The scripts in the script directory will always start with |
171 | the lowercased version of your application name. If your app is |
172 | MaiTai, then the create script would be "maitai_create.pl". |
173 | |
174 | Though it's too early for any significant celebration, we already have |
175 | a functioning application. We can use the Catalyst supplied script to |
176 | start up a development server and view the default Catalyst page in |
177 | your browser. All scripts in the script directory should be run from |
178 | the base directory of your application, so change to the Hello |
179 | directory. |
180 | |
181 | Run the following command to start up the built-in development web |
acbd7bdd |
182 | server (make sure you didn't forget the "C<cd Hello>" from the |
183 | previous step): |
d442cc9f |
184 | |
3533daff |
185 | $ script/hello_server.pl |
d442cc9f |
186 | [debug] Debug messages enabled |
865d3efb |
187 | [debug] Statistics enabled |
d442cc9f |
188 | [debug] Loaded plugins: |
189 | .----------------------------------------------------------------------------. |
865d3efb |
190 | | Catalyst::Plugin::ConfigLoader 0.20 | |
3533daff |
191 | | Catalyst::Plugin::Static::Simple 0.20 | |
d442cc9f |
192 | '----------------------------------------------------------------------------' |
193 | |
194 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
195 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
3533daff |
196 | [debug] Found home "/home/me/Hello" |
e13f83cc |
197 | [debug] Loaded Config "/home/me/Hello/hello.conf" |
d442cc9f |
198 | [debug] Loaded components: |
199 | .-----------------------------------------------------------------+----------. |
200 | | Class | Type | |
201 | +-----------------------------------------------------------------+----------+ |
3533daff |
202 | | Hello::Controller::Root | instance | |
d442cc9f |
203 | '-----------------------------------------------------------------+----------' |
204 | |
205 | [debug] Loaded Private actions: |
206 | .----------------------+--------------------------------------+--------------. |
207 | | Private | Class | Method | |
208 | +----------------------+--------------------------------------+--------------+ |
3533daff |
209 | | /default | Hello::Controller::Root | default | |
210 | | /end | Hello::Controller::Root | end | |
acbd7bdd |
211 | | /index | Hello::Controller::Root | index | |
d442cc9f |
212 | '----------------------+--------------------------------------+--------------' |
213 | |
865d3efb |
214 | [debug] Loaded Path actions: |
215 | .-------------------------------------+--------------------------------------. |
216 | | Path | Private | |
217 | +-------------------------------------+--------------------------------------+ |
218 | | / | /default | |
219 | | / | /index | |
220 | '-------------------------------------+--------------------------------------' |
acbd7bdd |
221 | |
fce83e5f |
222 | [info] Hello powered by Catalyst 5.80004 |
acbd7bdd |
223 | You can connect to your server at http://debian:3000 |
d442cc9f |
224 | |
1435672d |
225 | Point your web browser to L<http://localhost:3000> (substituting a |
d442cc9f |
226 | different hostname or IP address as appropriate) and you should be |
acbd7bdd |
227 | greeted by the Catalyst welcome screen (if you get some other welcome |
228 | screen or an "Index" screen, you probably forgot to specify port 3000 |
229 | in your URL). Information similar to the following should be appended |
230 | to the logging output of the development server: |
231 | |
232 | [info] *** Request 1 (0.005/s) [20712] [Sun Mar 8 15:49:09 2009] *** |
233 | [debug] "GET" request for "/" from "1.1.1.98" |
234 | [info] Request took 0.007342s (136.203/s) |
d442cc9f |
235 | .----------------------------------------------------------------+-----------. |
236 | | Action | Time | |
237 | +----------------------------------------------------------------+-----------+ |
acbd7bdd |
238 | | /index | 0.000491s | |
239 | | /end | 0.000595s | |
d442cc9f |
240 | '----------------------------------------------------------------+-----------' |
241 | |
242 | Press Ctrl-C to break out of the development server. |
243 | |
244 | |
3533daff |
245 | =head1 HELLO WORLD |
d442cc9f |
246 | |
3533daff |
247 | =head2 The Simplest Way |
d442cc9f |
248 | |
3533daff |
249 | The Root.pm controller is a place to put global actions that usually |
250 | execute on the root URL. Open the C<lib/Hello/Controller/Root.pm> file in |
865d3efb |
251 | your editor. You will see the "index" subroutine, which is |
3533daff |
252 | responsible for displaying the welcome screen that you just saw in |
253 | your browser. Later on you'll want to change that to something more |
865d3efb |
254 | reasonable, such as a "404" message or a redirect, but for now just |
255 | leave it alone. |
d442cc9f |
256 | |
865d3efb |
257 | sub index :Path :Args(0) { |
3533daff |
258 | my ( $self, $c ) = @_; |
865d3efb |
259 | |
260 | # Hello World |
3533daff |
261 | $c->response->body( $c->welcome_message ); |
d442cc9f |
262 | } |
263 | |
3533daff |
264 | The "C<$c>" here refers to the Catalyst context, which is used to |
265 | access the Catalyst application. In addition to many other things, |
266 | the Catalyst context provides access to "response" and "request" |
d0496197 |
267 | objects. (See L<Catalyst|Catalyst>, |
268 | L<Catalyst::Response|Catalyst::Response>, and |
269 | L<Catalyst::Request|Catalyst::Request>) |
d442cc9f |
270 | |
14e5ed66 |
271 | C<$c-E<gt>response-E<gt>body> sets the HTTP response (see |
272 | L<Catalyst::Response|Catalyst::Response>), while C<$c-E<gt>welcome_message> |
d0496197 |
273 | is a special method that returns the welcome message that you saw in |
274 | your browser. |
d442cc9f |
275 | |
865d3efb |
276 | The ":Path :Args(0)" after the method name are attributes which determine |
3533daff |
277 | which URLs will be dispatched to this method. (Depending on your version of |
865d3efb |
278 | Catalyst, it used to say "Private" but using that with 'default' or 'index' |
279 | is currently deprecated.) |
d442cc9f |
280 | |
3533daff |
281 | Some MVC frameworks handle dispatching in a central place. Catalyst, |
282 | by policy, prefers to handle URL dispatching with attributes on |
283 | controller methods. There is a lot of flexibility in specifying which |
284 | URLs to match. This particular method will match all URLs, because it |
865d3efb |
285 | doesn't specify the path (nothing comes after "Path"), but will only |
286 | accept a single args because of the ":Args(0)". |
d442cc9f |
287 | |
3533daff |
288 | The default is to map URLs to controller names, and because of |
289 | the way that Perl handles namespaces through package names, |
290 | it is simple to create hierarchical structures in |
291 | Catalyst. This means that you can create controllers with deeply |
292 | nested actions in a clean and logical way. |
d442cc9f |
293 | |
3533daff |
294 | For example, the URL C<http://hello.com/admin/articles/create> maps |
295 | to the package C<Hello::Controller::Admin::Articles>, and the C<create> |
296 | method. |
d442cc9f |
297 | |
d0496197 |
298 | Add the following subroutine to your C<lib/Hello/Controller/Root.pm> |
299 | file: |
d442cc9f |
300 | |
3533daff |
301 | sub hello : Global { |
302 | my ( $self, $c ) = @_; |
d0496197 |
303 | |
3533daff |
304 | $c->response->body("Hello, World!"); |
305 | } |
d442cc9f |
306 | |
acbd7bdd |
307 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
308 | cutting and pasting example code from POD-based documents. |
309 | |
3533daff |
310 | Here you're sending your own string to the webpage. |
311 | |
312 | Save the file, start the server (stop and restart it if it's still |
d0496197 |
313 | up), and go to L<http://localhost:3000/hello> to |
3533daff |
314 | see "Hello, World!" |
315 | |
865d3efb |
316 | |
3533daff |
317 | =head2 Hello, World! Using a View and a Template |
318 | |
319 | In the Catalyst world a "View" is not a page of XHTML or a template |
320 | designed to present a page to a browser. It is the module that |
865d3efb |
321 | determines the I<type> of view -- HTML, pdf, XML, etc. For the |
322 | thing that generates the I<content> of that view, (such as the |
323 | default Toolkit Template) the actual templates go under the |
324 | "root" directory. |
3533daff |
325 | |
326 | To create a TT view, run: |
327 | |
328 | $ script/hello_create.pl view TT TT |
329 | |
330 | This creates the C<lib/Hello/View/TT.pm> module, which is a subclass of |
1435672d |
331 | C<Catalyst::View::TT>. |
332 | |
333 | =over 4 |
334 | |
335 | =item * |
336 | |
337 | The "view" keyword tells the create script that you are creating a view. |
338 | |
339 | =item * |
340 | |
341 | The first "TT" tells the script to name the View module "TT.pm", which is a |
342 | commonly used name for TT views. (You can name it anything you want, such as |
343 | "HTML.pm".) |
344 | |
345 | =item * |
346 | |
347 | The final "TT" tells it that you are creating a Template Toolkit view. |
348 | |
349 | =back |
350 | |
351 | If you look at C<lib/Hello/View/TT.pm> you will find that it only contains a |
352 | config statement to set the TT extension to ".tt". |
3533daff |
353 | |
354 | Now that the TT.pm "View" exists, Catalyst will autodiscover it and be |
355 | able to use it to display the view templates, using the "process" |
356 | method that it inherits from the C<Catalyst::View::TT class>. |
357 | |
c010ae0d |
358 | Template Toolkit is a very full featured template facility, with |
865d3efb |
359 | excellent documentation at L<http://template-toolkit.org/>, |
3533daff |
360 | but since this is not a TT tutorial, we'll stick to only basic TT |
361 | usage here (and explore some of the more common TT features in later |
4b4d3884 |
362 | chapters of the tutorial). |
3533daff |
363 | |
364 | Create a C<root/hello.tt> template file (put it in the C<root> under |
365 | the C<Hello> directory that is the base of your application). Here is |
366 | a simple sample: |
367 | |
3533daff |
368 | <p> |
1435672d |
369 | This is a TT view template, called '[% template.name %]'. |
3533daff |
370 | </p> |
371 | |
372 | [% and %] are markers for the TT parts of the template. Inside you can |
1435672d |
373 | access Perl variables and classes, and use TT directives. In this |
374 | case, we're using a special TT variable that defines the name of the |
375 | template file (C<hello.tt>). The rest of the template is normal HTML. |
376 | |
377 | Change the hello method in C<lib/Hello/Controller/Root.pm> to the |
378 | following: |
3533daff |
379 | |
380 | sub hello : Global { |
381 | my ( $self, $c ) = @_; |
d0496197 |
382 | |
3533daff |
383 | $c->stash->{template} = 'hello.tt'; |
384 | } |
d442cc9f |
385 | |
1435672d |
386 | This time, instead of doing C<$c-E<gt>response-E<gt>body()>, you are setting |
3533daff |
387 | the value of the "template" hash key in the Catalyst "stash", an area |
388 | for putting information to share with other parts of your application. |
389 | The "template" key determines which template will be displayed at the |
390 | end of the method. Catalyst controllers have a default "end" action |
391 | for all methods which causes the first (or default) view to be |
1435672d |
392 | rendered (unless there's a C<$c-E<gt>response-E<gt>body()> statement). So your |
3533daff |
393 | template will be magically displayed at the end of your method. |
d442cc9f |
394 | |
3533daff |
395 | After saving the file, restart the development server, and look at |
d0496197 |
396 | L<http://localhost:3000/hello> again. You should |
3533daff |
397 | see the template that you just made. |
d442cc9f |
398 | |
d442cc9f |
399 | |
3533daff |
400 | =head1 CREATE A SIMPLE CONTROLLER AND AN ACTION |
d442cc9f |
401 | |
3533daff |
402 | Create a controller named "Site" by executing the create script: |
d442cc9f |
403 | |
3533daff |
404 | $ script/hello_create.pl controller Site |
d442cc9f |
405 | |
3533daff |
406 | This will create a C<lib/Hello/Controller/Site.pm> file (and a test |
407 | file). Bring Site.pm up in your editor, and you can see that there's |
408 | not much there. Most people probably don't bother to use the create |
409 | script to make controllers after they're used to using Catalyst. |
d442cc9f |
410 | |
d0496197 |
411 | In C<lib/Hello/Controller/Site.pm>, add the following method: |
d442cc9f |
412 | |
3533daff |
413 | sub test : Local { |
414 | my ( $self, $c ) = @_; |
d0496197 |
415 | |
3533daff |
416 | $c->stash->{username} = "John"; |
417 | $c->stash->{template} = 'site/test.tt'; |
d442cc9f |
418 | } |
419 | |
1435672d |
420 | Notice the "Local" attribute on the C<test> method. This will cause |
421 | the C<test> action (now that we have assigned an action type to the |
422 | method it appears as a controller "action" to Catalyst) to be executed |
423 | on the "controller/method" URL, or, in this case, "site/test". We |
424 | will see additional information on controller actions throughout the |
425 | rest of the tutorial, but if you are curious take a look at |
426 | L<Catalyst::Manual::Intro/Actions>. |
427 | |
428 | It's not actually necessary to set the template value as we do here. |
429 | By default TT will attempt to render a template that follows the |
430 | naming pattern "controller/method.tt", and we're following that |
431 | pattern here. However, in other situations you will need to specify |
432 | the template (such as if you've "forwarded" to the method, or if it |
433 | doesn't follow the default naming convention). |
434 | |
435 | We've also put the variable "username" into the stash, for use in the |
436 | template. |
d442cc9f |
437 | |
3533daff |
438 | Make a subdirectory "site" in the "root" directory. Copy the hello.tt |
d0496197 |
439 | file into the directory as C<root/site/test.tt>, or create a new |
440 | template file at that location. Include a line like: |
d442cc9f |
441 | |
d0496197 |
442 | <p>Hello, [% username %]!</p> |
d442cc9f |
443 | |
3533daff |
444 | Bring up or restart the server. Notice in the server output that |
445 | C</site/test> is listed in the Loaded Path actions. Go to |
865d3efb |
446 | L<http://localhost:3000/site/test> in your browser. |
d442cc9f |
447 | |
3533daff |
448 | You should see your test.tt file displayed, including the name "John" |
449 | that you set in the controller. |
d442cc9f |
450 | |
d442cc9f |
451 | |
3533daff |
452 | =head1 AUTHORS |
d442cc9f |
453 | |
3533daff |
454 | Gerda Shank, C<gerda.shank@gmail.com> |
d442cc9f |
455 | Kennedy Clark, C<hkclark@gmail.com> |
456 | |
457 | Please report any errors, issues or suggestions to the author. The |
458 | most recent version of the Catalyst Tutorial can be found at |
82ab4bbf |
459 | L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>. |
d442cc9f |
460 | |
45c7830f |
461 | Copyright 2006-2008, Kennedy Clark & Gerda Shank, under Creative Commons License |
865d3efb |
462 | (L<http://creativecommons.org/licenses/by-sa/3.0/us/>). |