Commit | Line | Data |
d442cc9f |
1 | =head1 NAME |
2 | |
3 | Catalyst::Manual::Tutorial::CatalystBasics - Catalyst Tutorial - Part 2: Catalyst Application Development Basics |
4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
8 | This is B<Part 2 of 9> for the Catalyst tutorial. |
9 | |
10 | L<Tutorial Overview|Catalyst::Manual::Tutorial> |
11 | |
12 | =over 4 |
13 | |
14 | =item 1 |
15 | |
16 | L<Introduction|Catalyst::Manual::Tutorial::Intro> |
17 | |
18 | =item 2 |
19 | |
20 | B<Catalyst Basics> |
21 | |
22 | =item 3 |
23 | |
24 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
25 | |
26 | =item 4 |
27 | |
28 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
29 | |
30 | =item 5 |
31 | |
32 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
33 | |
34 | =item 6 |
35 | |
36 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
37 | |
38 | =item 7 |
39 | |
40 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
41 | |
42 | =item 8 |
43 | |
44 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
45 | |
46 | =item 9 |
47 | |
48 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
49 | |
50 | =back |
51 | |
52 | |
53 | =head1 DESCRIPTION |
54 | |
55 | In this part of the tutorial, we will create a very basic Catalyst web |
56 | application. Though simple in many respects, this section will already |
57 | demonstrate a number of powerful capabilities such as: |
58 | |
59 | =over 4 |
60 | |
61 | =item * Helper Scripts |
62 | |
63 | Catalyst helper scripts that can be used to rapidly bootstrap the |
64 | skeletal structure of an application. |
65 | |
66 | =item * MVC |
67 | |
68 | Model/View/Controller (MVC) provides an architecture that facilitates a |
69 | clean "separation of control" between the different portions of your |
70 | application. Given that many other documents cover this subject in |
71 | detail, MVC will not be discussed in depth here (for an excellent |
72 | introduction to MVC and general Catalyst concepts, please see |
73 | L<Catalyst::Manual::About>. In short: |
74 | |
75 | =over 4 |
76 | |
77 | =item * Model |
78 | |
79 | The model usually represents a data store. In most applications, the |
80 | model equates to the objects that are created from and saved to your SQL |
81 | database. |
82 | |
83 | =item * View |
84 | |
85 | The view takes model objects and renders them into something for the end |
86 | user to look at. Normally this involves a template-generation tool that |
87 | creates HTML for the user's web browser, but it could easily be code |
88 | that generates other forms such as PDF documents, e-mails, or Excel |
89 | spreadsheets. |
90 | |
91 | =item * Controller |
92 | |
93 | As suggested by its name, the controller takes user requests and routes |
94 | them to the necessary model and view. |
95 | |
96 | =back |
97 | |
98 | =item * ORM |
99 | |
100 | The use of Object-Relational Mapping (ORM) technology for database |
101 | access. Specifically, ORM provides an automated and standardized means |
102 | to persist and restore objects to/from a relational database. |
103 | |
104 | =back |
105 | |
106 | You can checkout the source code for this example from the catalyst |
107 | subversion repository as per the instructions in |
108 | L<Catalyst::Manual::Tutorial::Intro> |
109 | |
110 | =head1 CREATE A CATALYST PROJECT |
111 | |
112 | Catalyst provides a number of helper scripts that can be used to quickly |
113 | flesh out the basic structure of your application. All Catalyst projects |
114 | begin with the C<catalyst.pl> helper (see L<Catalyst::Helper|Catalyst::Helper> |
115 | for more information on helpers). Also note that as of Catalyst 5.7000, |
116 | you will not have the helper scripts unless you install both |
117 | L<Catalyst::Runtime|Catalyst::Runtime> and L<Catalyst::Devel|Catalyst::Devel>. |
118 | |
119 | In the case of this tutorial, use the Catalyst C<catalyst.pl> script to |
120 | initialize the framework for an application called C<MyApp>: |
121 | |
122 | $ catalyst.pl MyApp |
123 | created "MyApp" |
124 | created "MyApp/script" |
125 | created "MyApp/lib" |
126 | created "MyApp/root" |
127 | ... |
128 | created "MyApp/script/myapp_create.pl" |
129 | $ cd MyApp |
130 | |
131 | The C<catalyst.pl> helper script will display the names of the |
132 | directories and files it creates. |
133 | |
134 | Though it's too early for any significant celebration, we already have a |
135 | functioning application. Run the following command to run this |
136 | application with the built-in development web server: |
137 | |
138 | $ script/myapp_server.pl |
139 | [debug] Debug messages enabled |
140 | [debug] Loaded plugins: |
141 | .----------------------------------------------------------------------------. |
142 | | Catalyst::Plugin::ConfigLoader 0.13 | |
143 | | Catalyst::Plugin::Static::Simple 0.14 | |
144 | '----------------------------------------------------------------------------' |
145 | |
146 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
147 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
148 | [debug] Found home "/home/me/MyApp" |
149 | [debug] Loaded Config "/home/me/myapp.yml" |
150 | [debug] Loaded components: |
151 | .-----------------------------------------------------------------+----------. |
152 | | Class | Type | |
153 | +-----------------------------------------------------------------+----------+ |
154 | | MyApp::Controller::Root | instance | |
155 | '-----------------------------------------------------------------+----------' |
156 | |
157 | [debug] Loaded Private actions: |
158 | .----------------------+--------------------------------------+--------------. |
159 | | Private | Class | Method | |
160 | +----------------------+--------------------------------------+--------------+ |
161 | | /default | MyApp::Controller::Root | default | |
162 | | /end | MyApp::Controller::Root | end | |
163 | '----------------------+--------------------------------------+--------------' |
164 | |
165 | [info] MyApp powered by Catalyst 5.7002 |
166 | You can connect to your server at http://localhost:3000 |
167 | |
168 | B<NOTE>: Be sure you run the C<script/myapp_server.pl> command from the |
169 | 'base' directory of your application, not inside the C<script> directory |
170 | itself. It doesn't make a difference at this point, but it will as soon |
171 | as we get the database going in the next section. |
172 | |
173 | Point your web browser to L<http://localhost:3000> (substituting a |
174 | different hostname or IP address as appropriate) and you should be |
175 | greeted by the Catalyst welcome screen. Information similar to the |
176 | following should be appended to the logging output of the development |
177 | server: |
178 | |
179 | [info] *** Request 1 (0.043/s) [6003] [Fri Jul 7 13:32:53 2006] *** |
180 | [debug] "GET" request for "/" from "127.0.0.1" |
181 | [info] Request took 0.067675s (14.777/s) |
182 | .----------------------------------------------------------------+-----------. |
183 | | Action | Time | |
184 | +----------------------------------------------------------------+-----------+ |
185 | | /default | 0.002844s | |
186 | | /end | 0.000207s | |
187 | '----------------------------------------------------------------+-----------' |
188 | |
189 | Press Ctrl-C to break out of the development server. |
190 | |
191 | |
192 | =head1 CREATE A SQLITE DATABASE |
193 | |
194 | In this step, we make a text file with the required SQL commands to |
195 | create a database table and load some sample data. Open C<myapp01.sql> |
196 | in your editor and enter: |
197 | |
198 | -- |
199 | -- Create a very simple database to hold book and author information |
200 | -- |
201 | CREATE TABLE books ( |
202 | id INTEGER PRIMARY KEY, |
203 | title TEXT , |
204 | rating INTEGER |
205 | ); |
206 | -- 'book_authors' is a many-to-many join table between books & authors |
207 | CREATE TABLE book_authors ( |
208 | book_id INTEGER, |
209 | author_id INTEGER, |
210 | PRIMARY KEY (book_id, author_id) |
211 | ); |
212 | CREATE TABLE authors ( |
213 | id INTEGER PRIMARY KEY, |
214 | first_name TEXT, |
215 | last_name TEXT |
216 | ); |
217 | --- |
218 | --- Load some sample data |
219 | --- |
220 | INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
221 | INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
222 | INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
223 | INSERT INTO books VALUES (4, 'Perl Cookbook', 5); |
224 | INSERT INTO books VALUES (5, 'Designing with Web Standards', 5); |
225 | INSERT INTO authors VALUES (1, 'Greg', 'Bastien'); |
226 | INSERT INTO authors VALUES (2, 'Sara', 'Nasseh'); |
227 | INSERT INTO authors VALUES (3, 'Christian', 'Degu'); |
228 | INSERT INTO authors VALUES (4, 'Richard', 'Stevens'); |
229 | INSERT INTO authors VALUES (5, 'Douglas', 'Comer'); |
230 | INSERT INTO authors VALUES (6, 'Tom', 'Christiansen'); |
231 | INSERT INTO authors VALUES (7, 'Nathan', 'Torkington'); |
232 | INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman'); |
233 | INSERT INTO book_authors VALUES (1, 1); |
234 | INSERT INTO book_authors VALUES (1, 2); |
235 | INSERT INTO book_authors VALUES (1, 3); |
236 | INSERT INTO book_authors VALUES (2, 4); |
237 | INSERT INTO book_authors VALUES (3, 5); |
238 | INSERT INTO book_authors VALUES (4, 6); |
239 | INSERT INTO book_authors VALUES (4, 7); |
240 | INSERT INTO book_authors VALUES (5, 8); |
241 | |
242 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
243 | cutting and pasting example code from POD-based documents. |
244 | |
245 | Then use the following command to build a C<myapp.db> SQLite database: |
246 | |
247 | $ sqlite3 myapp.db < myapp01.sql |
248 | |
249 | If you need to create the database more than once, you probably want to |
250 | issue the C<rm myapp.db> command to delete the database before you use |
251 | the C<sqlite3 myapp.db < myapp01.sql> command. |
252 | |
253 | Once the C<myapp.db> database file has been created and initialized, you |
254 | can use the SQLite command line environment to do a quick dump of the |
255 | database contents: |
256 | |
257 | $ sqlite3 myapp.db |
258 | SQLite version 3.2.2 |
259 | Enter ".help" for instructions |
260 | sqlite> select * from books; |
261 | 1|CCSP SNRS Exam Certification Guide|5 |
262 | 2|TCP/IP Illustrated, Volume 1|5 |
263 | 3|Internetworking with TCP/IP Vol.1|4 |
264 | 4|Perl Cookbook|5 |
265 | 5|Designing with Web Standards|5 |
266 | sqlite> .q |
267 | $ |
268 | |
269 | Or: |
270 | |
271 | $ sqlite3 myapp.db "select * from books" |
272 | 1|CCSP SNRS Exam Certification Guide|5 |
273 | 2|TCP/IP Illustrated, Volume 1|5 |
274 | 3|Internetworking with TCP/IP Vol.1|4 |
275 | 4|Perl Cookbook|5 |
276 | 5|Designing with Web Standards|5 |
277 | |
278 | As with most other SQL tools, if you are using the full "interactive" |
279 | environment you need to terminate your SQL commands with a ";" (it's not |
280 | required if you do a single SQL statement on the command line). Use |
281 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
282 | your OS command prompt. |
283 | |
284 | |
285 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
286 | |
287 | One of the greatest benefits of Catalyst is that it has such a large |
288 | library of plugins available. Plugins are used to seamlessly integrate |
289 | existing Perl modules into the overall Catalyst framework. In general, |
290 | they do this by adding additional methods to the C<context> object |
291 | (generally written as C<$c>) that Catalyst passes to every component |
292 | throughout the framework. |
293 | |
294 | By default, Catalyst enables three plugins/flags: |
295 | |
296 | =over 4 |
297 | |
298 | =item * |
299 | |
300 | C<-Debug> Flag |
301 | |
302 | Enables the Catalyst debug output you saw when we started the |
303 | C<script/myapp_server.pl> development server earlier. You can remove |
304 | this plugin when you place your application into production. |
305 | |
306 | As you may have noticed, C<-Debug> is not a plugin, but a I<flag>. |
307 | Although most of the items specified on the C<use Catalyst> line of your |
308 | application class will be plugins, Catalyst supports a limited number of |
309 | flag options (of these, C<-Debug> is the most common). See the |
310 | documentation for C<Catalyst.pm> to get details on other flags |
311 | (currently C<-Engine>, C<-Home>, and C<-Log>). |
312 | |
313 | If you prefer, you can use the C<$c-E<gt>debug> method to enable debug |
314 | messages. |
315 | |
316 | =item * |
317 | |
318 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
319 | |
320 | C<ConfigLoader> provides an automatic way to load configurable |
321 | parameters for your application from a central YAML file (versus having |
322 | the values hard-coded inside your Perl modules). If you have not been |
323 | exposed to YAML before, it is a human-readable data serialization format |
324 | that can be used to read (and write) values to/from text files. We will |
325 | see how to use this feature of Catalyst during the authentication and |
326 | authorization sections (Part 4 and Part 5). |
327 | |
328 | =item * |
329 | |
330 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
331 | |
332 | C<Static::Simple> provides an easy method of serving static content such |
333 | as images and CSS files under the development server. |
334 | |
335 | =back |
336 | |
337 | To modify the list of plugins, edit C<lib/MyApp.pm> (this file is |
338 | generally referred to as your I<application class>) and delete the line |
339 | with: |
340 | |
341 | use Catalyst qw/-Debug ConfigLoader Static::Simple/; |
342 | |
343 | Replace it with: |
344 | |
345 | use Catalyst qw/ |
346 | -Debug |
347 | ConfigLoader |
348 | Static::Simple |
349 | |
350 | StackTrace |
351 | /; |
352 | |
353 | This tells Catalyst to start using one new plugin: |
354 | |
355 | =over 4 |
356 | |
357 | =item * |
358 | |
359 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace> |
360 | |
361 | Adds a stack trace to the standard Catalyst "debug screen" (this is the |
362 | screen Catalyst sends to your browser when an error occurs). |
363 | |
364 | Note: L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
365 | browser, not in the console window from which you're running your |
366 | application, which is where logging output usually goes. |
367 | |
368 | =back |
369 | |
370 | Note that when specifying plugins on the C<use Catalyst> line, you can |
371 | omit C<Catalyst::Plugin::> from the name. Additionally, you can spread |
372 | the plugin names across multiple lines as shown here, or place them all |
373 | on one (or more) lines as with the default configuration. |
374 | |
375 | B<TIP:> You may see examples that include the |
376 | L<Catalyst::Plugin::DefaultEnd|Catalyst::Plugin::DefaultEnd> |
377 | plugins. As of Catalyst 5.7000, C<DefaultEnd> has been |
378 | deprecated in favor of |
379 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> |
380 | (as the name of the package suggests, C<RenderView> is not |
381 | a plugin, but an action). The purpose of both is essentially the same: |
382 | forward processing to the view to be rendered. Applications generated |
383 | under 5.7000 should automatically use C<RenderView> and "just work" |
384 | for most applications. For more information on C<RenderView> and |
385 | the various options for forwarding to your view logic, please refer |
386 | to the "Using RenderView for the Default View" section under |
387 | "CATALYST VIEWS" below. |
388 | |
389 | |
390 | =head1 DATABASE ACCESS WITH C<DBIx::Class> |
391 | |
392 | Catalyst can be used with virtually any form of persistent datastore |
393 | available via Perl. For example, |
394 | L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to |
395 | easily access databases through the traditional Perl C<DBI> interface. |
396 | However, most Catalyst applications use some form of ORM technology to |
397 | automatically create and save model objects as they are used. Although |
398 | Tony Bowden's L<Class::DBI|Class::DBI> has been the traditional |
399 | Perl ORM engine, Matt Trout's L<DBIx::Class|DBIx::Class> (abbreviated |
400 | as "DBIC") has rapidly emerged as the Perl-based ORM technology of choice. |
401 | Most new Catalyst applications rely on DBIC, as will this tutorial. |
402 | |
403 | Note: See L<Catalyst::Model::CDBI> for more information on using |
404 | Catalyst with L<Class::DBI|Class::DBI>. |
405 | |
406 | =head2 Create a DBIC Schema File |
407 | |
408 | DBIx::Class uses a schema file to load other classes that represent the |
409 | tables in your database (DBIC refers to these "table objects" as "result |
410 | sources"; see L<DBIx::Class::ResultSource>). In this case, we want to |
411 | load the model object for the C<books>, C<book_authors>, and C<authors> |
412 | tables created in the previous step. |
413 | |
414 | Create C<lib/MyAppDB.pm> in your editor and insert: |
415 | |
416 | package MyAppDB; |
417 | |
418 | =head1 NAME |
419 | |
420 | MyAppDB - DBIC Schema Class |
421 | |
422 | =cut |
423 | |
424 | # Our schema needs to inherit from 'DBIx::Class::Schema' |
425 | use base qw/DBIx::Class::Schema/; |
426 | |
427 | # Need to load the DB Model classes here. |
428 | # You can use this syntax if you want: |
429 | # __PACKAGE__->load_classes(qw/Book BookAuthor Author/); |
430 | # Also, if you simply want to load all of the classes in a directory |
431 | # of the same name as your schema class (as we do here) you can use: |
432 | # __PACKAGE__->load_classes(qw//); |
433 | # But the variation below is more flexible in that it can be used to |
434 | # load from multiple namespaces. |
435 | __PACKAGE__->load_classes({ |
436 | MyAppDB => [qw/Book BookAuthor Author/] |
437 | }); |
438 | |
439 | 1; |
440 | |
441 | B<Note:> C<__PACKAGE__> is just a shorthand way of referencing the name |
442 | of the package where it is used. Therefore, in C<MyAppDB.pm>, |
443 | C<__PACKAGE__> is equivalent to C<MyAppDB>. |
444 | |
445 | B<Note:> As with any Perl package, we need to end the last line with |
446 | a statement that evaluates to C<true>. This is customarily done with |
447 | C<1> on a line by itself as shown above. |
448 | |
449 | |
450 | =head2 Create the DBIC "Result Source" Files |
451 | |
452 | In this step, we create "table classes" (again, these are called a |
453 | "result source" classes in DBIC) that act as model objects for the |
454 | C<books>, C<book_authors>, and C<authors> tables in our database. |
455 | |
456 | First, create a directory to hold the class: |
457 | |
458 | $ mkdir lib/MyAppDB |
459 | |
460 | Then create C<lib/MyAppDB/Book.pm> in your editor and enter: |
461 | |
462 | package MyAppDB::Book; |
463 | |
464 | use base qw/DBIx::Class/; |
465 | |
466 | # Load required DBIC stuff |
467 | __PACKAGE__->load_components(qw/PK::Auto Core/); |
468 | # Set the table name |
469 | __PACKAGE__->table('books'); |
470 | # Set columns in table |
471 | __PACKAGE__->add_columns(qw/id title rating/); |
472 | # Set the primary key for the table |
473 | __PACKAGE__->set_primary_key(qw/id/); |
474 | |
475 | # |
476 | # Set relationships: |
477 | # |
478 | |
479 | # has_many(): |
480 | # args: |
481 | # 1) Name of relationship, DBIC will create accessor with this name |
482 | # 2) Name of the model class referenced by this relationship |
483 | # 3) Column name in *foreign* table |
484 | __PACKAGE__->has_many(book_authors => 'MyAppDB::BookAuthor', 'book_id'); |
485 | |
486 | # many_to_many(): |
487 | # args: |
488 | # 1) Name of relationship, DBIC will create accessor with this name |
489 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
490 | # 3) Name of belongs_to() relationship in model class of has_many() above |
491 | # You must already have the has_many() defined to use a many_to_many(). |
492 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
493 | |
494 | |
495 | =head1 NAME |
496 | |
497 | MyAppDB::Book - A model object representing a book. |
498 | |
499 | =head1 DESCRIPTION |
500 | |
501 | This is an object that represents a row in the 'books' table of your application |
502 | database. It uses DBIx::Class (aka, DBIC) to do ORM. |
503 | |
504 | For Catalyst, this is designed to be used through MyApp::Model::MyAppDB. |
505 | Offline utilities may wish to use this class directly. |
506 | |
507 | =cut |
508 | |
509 | 1; |
510 | |
511 | This defines both a C<has_many> and a C<many_to_many> relationship. The |
512 | C<many_to_many> relationship is optional, but it makes it easier to map |
513 | a book to its collection of authors. Without it, we would have to |
514 | "walk" though the C<book_authors> table as in |
515 | C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name> (we |
516 | will see examples on how to use DBIC objects in your code soon, but note |
517 | that because C<$book-E<gt>book_authors> can return multiple authors, we |
518 | have to use C<first> to display a single author). C<many_to_many> allows |
519 | us to use the shorter C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. |
520 | Note that you cannot define a C<many_to_many> relationship without also |
521 | having the C<has_many> relationship in place. |
522 | |
523 | Next, create C<lib/MyAppDB/Author.pm> in your editor and enter: |
524 | |
525 | package MyAppDB::Author; |
526 | |
527 | use base qw/DBIx::Class/; |
528 | |
529 | # Load required DBIC stuff |
530 | __PACKAGE__->load_components(qw/PK::Auto Core/); |
531 | # Set the table name |
532 | __PACKAGE__->table('authors'); |
533 | # Set columns in table |
534 | __PACKAGE__->add_columns(qw/id first_name last_name/); |
535 | # Set the primary key for the table |
536 | __PACKAGE__->set_primary_key(qw/id/); |
537 | |
538 | # |
539 | # Set relationships: |
540 | # |
541 | |
542 | # has_many(): |
543 | # args: |
544 | # 1) Name of relationship, DBIC will create accessor with this name |
545 | # 2) Name of the model class referenced by this relationship |
546 | # 3) Column name in *foreign* table |
547 | __PACKAGE__->has_many(book_author => 'MyAppDB::BookAuthor', 'author_id'); |
548 | |
549 | # many_to_many(): |
550 | # args: |
551 | # 1) Name of relationship, DBIC will create accessor with this name |
552 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
553 | # 3) Name of belongs_to() relationship in model class of has_many() above |
554 | # You must already have the has_many() defined to use a many_to_many(). |
555 | __PACKAGE__->many_to_many(books => 'book_author', 'book'); |
556 | |
557 | |
558 | =head1 NAME |
559 | |
560 | MyAppDB::Author - A model object representing an author of a book (if a book has |
561 | multiple authors, each will be represented be separate Author object). |
562 | |
563 | =head1 DESCRIPTION |
564 | |
565 | This is an object that represents a row in the 'authors' table of your application |
566 | database. It uses DBIx::Class (aka, DBIC) to do ORM. |
567 | |
568 | For Catalyst, this is designed to be used through MyApp::Model::MyAppDB. |
569 | Offline utilities may wish to use this class directly. |
570 | |
571 | =cut |
572 | |
573 | 1; |
574 | |
575 | Finally, create C<lib/MyAppDB/BookAuthor.pm> in your editor and enter: |
576 | |
577 | package MyAppDB::BookAuthor; |
578 | |
579 | use base qw/DBIx::Class/; |
580 | |
581 | # Load required DBIC stuff |
582 | __PACKAGE__->load_components(qw/PK::Auto Core/); |
583 | # Set the table name |
584 | __PACKAGE__->table('book_authors'); |
585 | # Set columns in table |
586 | __PACKAGE__->add_columns(qw/book_id author_id/); |
587 | # Set the primary key for the table |
588 | __PACKAGE__->set_primary_key(qw/book_id author_id/); |
589 | |
590 | # |
591 | # Set relationships: |
592 | # |
593 | |
594 | # belongs_to(): |
595 | # args: |
596 | # 1) Name of relationship, DBIC will create accessor with this name |
597 | # 2) Name of the model class referenced by this relationship |
598 | # 3) Column name in *this* table |
599 | __PACKAGE__->belongs_to(book => 'MyAppDB::Book', 'book_id'); |
600 | |
601 | # belongs_to(): |
602 | # args: |
603 | # 1) Name of relationship, DBIC will create accessor with this name |
604 | # 2) Name of the model class referenced by this relationship |
605 | # 3) Column name in *this* table |
606 | __PACKAGE__->belongs_to(author => 'MyAppDB::Author', 'author_id'); |
607 | |
608 | |
609 | =head1 NAME |
610 | |
611 | MyAppDB::BookAuthor - A model object representing the JOIN between an author and |
612 | a book. |
613 | |
614 | =head1 DESCRIPTION |
615 | |
616 | This is an object that represents a row in the 'book_authors' table of your |
617 | application database. It uses DBIx::Class (aka, DBIC) to do ORM. |
618 | |
619 | You probably won't need to use this class directly -- it will be automatically |
620 | used by DBIC where joins are needed. |
621 | |
622 | For Catalyst, this is designed to be used through MyApp::Model::MyAppDB. |
623 | Offline utilities may wish to use this class directly. |
624 | |
625 | =cut |
626 | |
627 | 1; |
628 | |
629 | B<Note:> This sample application uses a plural form for the database |
630 | tables (e.g., C<books> and C<authors>) and a singular form for the model |
631 | objects (e.g., C<Book> and C<Author>); however, Catalyst places no |
632 | restrictions on the naming conventions you wish to use. |
633 | |
634 | =head2 Use C<Catalyst::Model::DBIC::Schema> To Load The Model Class |
635 | |
636 | When L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> is |
637 | in use, Catalyst essentially reads an existing copy of your database |
638 | model and creates a new set of objects under C<MyApp::Model> for use |
639 | inside of Catalyst. |
640 | |
641 | B<Note:> With |
642 | L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> you |
643 | essentially end up with two sets of model classes (only one of which |
644 | you write... the other set is created automatically in memory when |
645 | your Catalyst application initializes). For this tutorial application, |
646 | the important points to remember are: you write the I<result source> |
647 | files in C<MyAppDB>, but I<within Catalyst> you use the I<automatically |
648 | created model classes> in C<MyApp::Model>. |
649 | |
650 | Use the |
651 | L<Catalyst::Helper::Model::DBIC::Schema|Catalyst::Helper::Model::DBIC::Schema> |
652 | helper script to create the model class that loads up the model we |
653 | created in the previous step: |
654 | |
655 | $ script/myapp_create.pl model MyAppDB DBIC::Schema MyAppDB dbi:SQLite:myapp.db '' '' '{ AutoCommit => 1 }' |
656 | exists "/root/dev/MyApp/script/../lib/MyApp/Model" |
657 | exists "/root/dev/MyApp/script/../t" |
658 | created "/root/dev/MyApp/script/../lib/MyApp/Model/MyAppDB.pm" |
659 | created "/root/dev/MyApp/script/../t/model_MyAppDB.t" |
660 | |
661 | |
662 | Where the first C<MyAppDB> is the name of the class to be created by the |
663 | helper in C<lib/MyApp/Model> and the second C<MyAppDB> is the name of |
664 | existing schema file we created (in C<lib/MyAppDB.pm>). You can see |
665 | that the helper creates a model file under C<lib/MyApp/Model> (Catalyst |
666 | has a separate directory under C<lib/MyApp> for each of the three parts |
667 | of MVC: C<Model>, C<View>, and C<Controller> [although older Catalyst |
668 | applications often use the directories C<M>, C<V>, and C<C>]). |
669 | |
670 | |
671 | =head1 CREATE A CATALYST CONTROLLER |
672 | |
673 | Controllers are where you write methods that interact with user |
674 | input--typically, controller methods respond to C<GET> and C<POST> |
675 | messages from the user's web browser. |
676 | |
677 | Use the Catalyst C<create> script to add a controller for book-related |
678 | actions: |
679 | |
680 | $ script/myapp_create.pl controller Books |
681 | exists "/root/dev/MyApp/script/../lib/MyApp/Controller" |
682 | exists "/root/dev/MyApp/script/../t" |
683 | created "/root/dev/MyApp/script/../lib/MyApp/Controller/Books.pm" |
684 | created "/root/dev/MyApp/script/../t/controller_Books.t" |
685 | |
686 | Then edit C<lib/MyApp/Controller/Books.pm> and add the following method |
687 | to the controller: |
688 | |
689 | =head2 list |
690 | |
691 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
692 | |
693 | =cut |
694 | |
695 | sub list : Local { |
696 | # Retrieve the usual perl OO '$self' for this object. $c is the Catalyst |
697 | # 'Context' that's used to 'glue together' the various components |
698 | # that make up the application |
699 | my ($self, $c) = @_; |
700 | |
701 | # Retrieve all of the book records as book model objects and store in the |
702 | # stash where they can be accessed by the TT template |
703 | $c->stash->{books} = [$c->model('MyAppDB::Book')->all]; |
704 | |
705 | # Set the TT template to use. You will almost always want to do this |
706 | # in your action methods (action methods respond to user input in |
707 | # your controllers). |
708 | $c->stash->{template} = 'books/list.tt2'; |
709 | } |
710 | |
711 | B<Note:> Programmers experienced with object-oriented Perl should |
712 | recognize C<$self> as a reference to the object where this method was |
713 | called. On the other hand, C<$c> will be new to many Perl programmers |
714 | who have not used Catalyst before (it's sometimes written as |
715 | C<$context>). The Context object is automatically passed to all |
716 | Catalyst components. It is used to pass information between components |
717 | and provide access to Catalyst and plugin functionality. |
718 | |
719 | B<TIP>: You may see the C<$c-E<gt>model('MyAppDB::Book')> used above |
720 | written as C<$c-E<gt>model('MyAppDB')-E<gt>resultset('Book)>. The two |
721 | are equivalent. |
722 | |
723 | B<Note:> Catalyst actions are regular Perl methods, but they make use of |
724 | Nicholas Clark's C<attributes> module (that's the C<: Local> next to the |
725 | C<sub list> in the code above) to provide additional information to the |
726 | Catalyst dispatcher logic. |
727 | |
728 | |
729 | =head1 CATALYST VIEWS |
730 | |
731 | Views are where you render output, typically for display in the user's |
732 | web browser, but also possibly using other display output-generation |
733 | systems. As with virtually every aspect of Catalyst, options abound |
734 | when it comes to the specific view technology you adopt inside your |
735 | application. However, most Catalyst applications use the Template |
736 | Toolkit, known as TT (for more information on TT, see |
737 | L<http://www.template-toolkit.org>). Other popular view technologies |
738 | include Mason (L<http://www.masonhq.com> and |
739 | L<http://www.masonbook.com>) and L<HTML::Template|HTML::Template> |
740 | (L<http://html-template.sourceforge.net>). |
741 | |
742 | =head2 Create a Catalyst View Using C<TTSite> |
743 | |
744 | When using TT for the Catalyst view, there are two main helper scripts: |
745 | |
746 | =over 4 |
747 | |
748 | =item * |
749 | |
750 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT> |
751 | |
752 | =item * |
753 | |
754 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite> |
755 | |
756 | =back |
757 | |
758 | Both are similar, but C<TT> merely creates the C<lib/MyApp/View/TT.pm> |
759 | file and leaves the creation of any hierarchical template organization |
760 | entirely up to you. (It also creates a C<t/view_TT.t> file for testing; |
761 | test cases will be discussed in Part 7). The C<TTSite> helper creates a |
762 | modular and hierarchical view layout with separate Template Toolkit (TT) |
763 | files for common header and footer information, configuration values, a |
764 | CSS stylesheet, and more. |
765 | |
7a600bfe |
766 | While TTSite is useful to bootstrap a project, we recommend that |
767 | unless you know what your're doing or want to pretty much use the |
768 | supplied templates as is, that you use the plain Template Toolkit view |
769 | when starting a project from scratch. This is because TTSite can be |
770 | tricky to customize. Additionally TT contains constructs that you |
771 | need to learn yourself if you're going to be a serious user of TT. |
772 | Our experience suggests that you're better off learning these from |
ac379833 |
773 | scratch. We use TTSite here precisely because it is useful for |
7a600bfe |
774 | bootstrap/prototype purposes. |
775 | |
d442cc9f |
776 | Enter the following command to enable the C<TTSite> style of view |
777 | rendering for this tutorial: |
778 | |
779 | $ script/myapp_create.pl view TT TTSite |
780 | exists "/root/dev/MyApp/script/../lib/MyApp/View" |
781 | exists "/root/dev/MyApp/script/../t" |
782 | created "/root/dev/MyApp/script/../lib/MyApp/View/TT.pm" |
783 | created "/root/dev/MyApp/script/../root/lib" |
784 | ... |
785 | created "/root/dev/MyApp/script/../root/src/ttsite.css" |
786 | |
787 | This puts a number of files in the C<root/lib> and C<root/src> |
788 | directories that can be used to customize the look and feel of your |
789 | application. Also take a look at C<lib/MyApp/View/TT.pm> for config |
790 | values set by the C<TTSite> helper. |
791 | |
792 | B<TIP>: Note that TTSite does one thing that could confuse people who |
793 | are used to the normal C<TT> Catalyst view: it redefines the Catalyst |
794 | context object in templates from its usual C<c> to C<Catalyst>. When |
795 | looking at other Catalyst examples, remember that they almost always use |
796 | C<c>. Note that Catalyst and TT I<do not complain> when you use the |
797 | wrong name to access the context object...TT simply outputs blanks for |
798 | that bogus logic (see next tip to change this behavior with TT C<DEBUG> |
799 | options). Finally, be aware that this change in name I<only> |
800 | applies to how the context object is accessed inside your TT templates; |
801 | your controllers will continue to use C<$c> (or whatever name you use |
802 | when fetching the reference from C<@_> inside your methods). (You can |
803 | change back to the "default" behavior be removing the C<CATALYST_VAR> |
804 | line from C<lib/MyApp/View/TT.pm>, but you will also have to edit |
805 | C<root/lib/config/main> and C<root/lib/config/url>. If you do this, be |
806 | careful not to have a collision between your own C<c> variable and the |
807 | Catalyst C<c> variable.) |
808 | |
809 | B<TIP>: When troubleshooting TT it can be helpful to enable variable |
810 | C<DEBUG> options. You can do this in a Catalyst environment by adding |
811 | a C<DEBUG> line to the C<__PACKAGE__->config> declaration in |
812 | C<lib/MyApp/View/TT.pm>: |
813 | |
814 | __PACKAGE__->config({ |
815 | CATALYST_VAR => 'Catalyst', |
816 | ... |
817 | DEBUG => 'undef', |
818 | ... |
819 | }); |
820 | |
821 | There are a variety of options you can use, such as 'undef', 'all', |
822 | 'service', 'context', 'parser', 'provider', and 'service'. See |
823 | L<Template::Constants> for more information (remove the C<DEBUG_> |
824 | portion of the name shown in the TT docs and convert to lower case |
825 | for use inside Catalyst). |
826 | |
827 | B<NOTE:> Please be sure to disable TT debug options before |
828 | continuing the tutorial (especially the 'undef' option -- leaving |
829 | this enabled will conflict with several of the conventions used |
830 | by this tutorial and TTSite to leave some variables undefined |
831 | on purpose). |
832 | |
833 | |
834 | =head2 Using C<RenderView> for the Default View |
835 | |
836 | Once your controller logic has processed the request from a user, it |
837 | forwards processing to your view in order to generate the appropriate |
838 | response output. Catalyst v5.7000 ships with a new mechanism, |
839 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView>, that |
840 | automatically performs this operation. If you look in |
841 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
842 | definition for the C<sub end> method: |
843 | |
844 | sub end : ActionClass('RenderView') {} |
845 | |
846 | The following bullet points provide a quick overview of the |
847 | C<RenderView> process: |
848 | |
849 | =over 4 |
850 | |
851 | =item * |
852 | |
853 | C<Root.pm> is designed to hold application-wide logic. |
854 | |
855 | =item * |
856 | |
857 | At the end of a given user request, Catalyst will call the most specific |
858 | C<end> method that's appropriate. For example, if the controller for a |
859 | request has an C<end> method defined, it will be called. However, if |
860 | the controller does not define a controller-specific C<end> method, the |
861 | "global" C<end> method in C<Root.pm> will be called. |
862 | |
863 | =item * |
864 | |
865 | Because the definition includes an C<ActionClass> attribute, the |
866 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
867 | will be executed B<after> any code inside the definition of C<sub end> |
868 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
869 | for more information on C<ActionClass>. |
870 | |
871 | =item * |
872 | |
873 | Because C<sub end> is empty, this effectively just runs the default |
874 | logic in C<RenderView>. However, you can easily extend the |
875 | C<RenderView> logic by adding your own code inside the empty method body |
876 | (C<{}>) created by the Catalyst Helpers when we first ran the |
877 | C<catalyst.pl> to initialize our application. See |
878 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
879 | detailed information on how to extended C<RenderView> in C<sub end>. |
880 | |
881 | =back |
882 | |
883 | |
884 | =head3 The History Leading Up To C<RenderView> |
885 | |
886 | Although C<RenderView> strikes a nice balance between default |
887 | behavior and easy extensibility, it is a new feature that won't |
888 | appear in most existing Catalyst examples. This section provides |
889 | some brief background on the evolution of default view rendering |
890 | logic with an eye to how they can be migrated to C<RenderView>: |
891 | |
892 | =over 4 |
893 | |
894 | =item * |
895 | |
896 | Private C<end> Action in Application Class |
897 | |
898 | Older Catalyst-related documents often suggest that you add a "private |
899 | end action" to your application class (C<MyApp.pm>) or Root.pm |
900 | (C<MyApp/Controller/Root.pm>). These examples should be easily |
901 | converted to L<RenderView|Catalyst::Action::RenderView> by simply adding |
902 | the attribute C<:ActionClass('RenderView')> to the C<sub end> |
903 | definition. If end sub is defined in your application class |
904 | (C<MyApp.pm>), you should also migrate it to |
905 | C<MyApp/Controller/Root.pm>. |
906 | |
907 | =item * |
908 | |
909 | L<Catalyst::Plugin::DefaultEnd|Catalyst::Plugin::DefaultEnd> |
910 | |
911 | C<DefaultEnd> represented the "next step" in passing processing from |
912 | your controller to your view. It has the advantage of only requiring |
913 | that C<DefaultEnd> be added to the list of plugins in C<lib/MyApp.pm>. |
914 | It also allowed you to add "dump_info=1" (precede with "?" or "&" |
915 | depending on where it is in the URL) to I<force> the debug screen at the |
916 | end of the Catalyst request processing cycle. However, it was more |
917 | difficult to extend than the C<RenderView> mechanism, and is now |
918 | deprecated. |
919 | |
920 | =item * |
921 | |
922 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> |
923 | |
924 | As discussed above, the current recommended approach to handling your |
925 | view logic relies on |
926 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView>. Although |
927 | similar in first appearance to the "private end action" approach, it |
928 | utilizes Catalyst's "ActionClass" mechanism to provide both automatic |
929 | default behavior (you don't have to include a plugin as with |
930 | C<DefaultEnd>) and easy extensibility. As with C<DefaultEnd>, it allows |
931 | you to add "dump_info=1" (precede with "?" or "&" depending on where it |
932 | is in the URL) to I<force> the debug screen at the end of the Catalyst |
933 | request processing cycle. |
934 | |
935 | =back |
936 | |
937 | It is recommended that all Catalyst applications use or migrate to |
938 | the C<RenderView> approach. |
939 | |
940 | |
941 | =head2 Globally Customize Every View |
942 | |
943 | When using TTSite, files in the subdirectories of C<root/lib> can be |
944 | used to make changes that will appear in every view. For example, to |
945 | display optional status and error messages in every view, edit |
946 | C<root/lib/site/layout>, updating it to match the following (the two HTML |
947 | C<span> elements are new): |
948 | |
949 | <div id="header">[% PROCESS site/header %]</div> |
950 | |
951 | <div id="content"> |
952 | <span class="message">[% status_msg %]</span> |
953 | <span class="error">[% error_msg %]</span> |
954 | [% content %] |
955 | </div> |
956 | |
957 | <div id="footer">[% PROCESS site/footer %]</div> |
958 | |
959 | If we set either message in the Catalyst stash (e.g., |
960 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it will |
961 | be displayed whenever any view used by that request is rendered. The |
962 | C<message> and C<error> CSS styles are automatically defined in |
963 | C<root/src/ttsite.css> and can be customized to suit your needs. |
964 | |
965 | B<Note:> The Catalyst stash only lasts for a single HTTP request. If |
966 | you need to retain information across requests you can use |
967 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
968 | Catalyst sessions in the Authentication part of the tutorial). |
969 | |
970 | |
971 | =head2 Create a TT Template Page |
972 | |
973 | To add a new page of content to the TTSite view hierarchy, just create a |
974 | new C<.tt2> file in C<root/src>. Only include HTML markup that goes |
975 | inside the HTML <body> and </body> tags, TTSite will use the contents of |
976 | C<root/lib/site> to add the top and bottom. |
977 | |
978 | First create a directory for book-related TT templates: |
979 | |
980 | $ mkdir root/src/books |
981 | |
982 | Then create C<root/src/books/list.tt2> in your editor and enter: |
983 | |
984 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
985 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
986 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
987 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
988 | |
989 | [% # Provide a title to root/lib/site/header -%] |
990 | [% META title = 'Book List' -%] |
991 | |
992 | <table> |
993 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
994 | [% # Display each book in a table row %] |
995 | [% FOREACH book IN books -%] |
996 | <tr> |
997 | <td>[% book.title %]</td> |
998 | <td>[% book.rating %]</td> |
999 | <td> |
1000 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
1001 | [% # loop in 'side effect notation' to load just the last names of the -%] |
1002 | [% # authors into the list. Note that the 'push' TT vmethod does not -%] |
1003 | [% # a value, so nothing will be printed here. But, if you have something -%] |
1004 | [% # in TT that does return a method and you don't want it printed, you -%] |
1005 | [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%] |
1006 | [% # call it and discard the return value. -%] |
1007 | [% tt_authors = [ ]; |
1008 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
1009 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
1010 | ([% tt_authors.size %]) |
1011 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
1012 | [% tt_authors.join(', ') %] |
1013 | </td> |
1014 | </tr> |
1015 | [% END -%] |
1016 | </table> |
1017 | |
1018 | As indicated by the inline comments above, the C<META title> line uses |
1019 | TT's META feature to provide a title to C<root/lib/site/header>. |
1020 | Meanwhile, the outer C<FOREACH> loop iterates through each C<book> model |
1021 | object and prints the C<title> and C<rating> fields. An inner |
1022 | C<FOREACH> loop prints the last name of each author in a comma-separated |
1023 | list within a single table cell. |
1024 | |
1025 | If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT |
1026 | code. TT supports a wide variety of directives for "calling" other |
1027 | files, looping, conditional logic, etc. In general, TT simplifies the |
1028 | usual range of Perl operators down to the single dot (C<.>) operator. |
1029 | This applies to operations as diverse as method calls, hash lookups, and |
1030 | list index values (see |
1031 | L<http://www.template-toolkit.org/docs/default/Manual/Variables.html> |
1032 | for details and examples). In addition to the usual C<Template> module |
1033 | Pod documentation, you can access the TT manual at |
1034 | L<http://www.template-toolkit.org/docs/default/>. |
1035 | |
1036 | B<NOTE>: The C<TTSite> helper creates several TT files using an |
1037 | extension of C<.tt2>. Most other Catalyst and TT examples use an |
1038 | extension of C<.tt>. You can use either extension (or no extension at |
1039 | all) with TTSite and TT, just be sure to use the appropriate extension |
1040 | for both the file itself I<and> the C<$c-E<gt>stash-E<gt>{template} = |
1041 | ...> line in your controller. This document will use C<.tt2> for |
1042 | consistency with the files already created by the C<TTSite> helper. |
1043 | |
1044 | |
1045 | =head1 RUN THE APPLICATION |
1046 | |
1047 | First, let's enable an environment variable option that causes |
1048 | DBIx::Class to dump the SQL statements it's using to access the database |
1049 | (this option can provide extremely helpful troubleshooting information): |
1050 | |
1051 | $ export DBIC_TRACE=1 |
1052 | |
1053 | B<NOTE>: You can also use the older |
1054 | C<export DBIX_CLASS_STORAGE_DBI_DEBUG=1>, but that's a lot more to |
1055 | type. |
1056 | |
1057 | This assumes you are using BASH as your shell -- adjust accordingly if |
1058 | you are using a different shell (for example, under tcsh, use |
1059 | C<setenv DBIX_CLASS_STORAGE_DBI_DEBUG 1>). |
1060 | |
1061 | B<NOTE>: You can also set this in your code using |
1062 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
1063 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
1064 | to log to file instead of displaying to the Catalyst development server |
1065 | log). |
1066 | |
1067 | Then run the Catalyst "demo server" script: |
1068 | |
1069 | $ script/myapp_server.pl |
1070 | |
1071 | Your development server log output should display something like: |
1072 | |
1073 | $ script/myapp_server.pl |
1074 | [debug] Debug messages enabled |
1075 | [debug] Loaded plugins: |
1076 | .----------------------------------------------------------------------------. |
1077 | | Catalyst::Plugin::ConfigLoader 0.13 | |
1078 | | Catalyst::Plugin::StackTrace 0.06 | |
1079 | | Catalyst::Plugin::Static::Simple 0.14 | |
1080 | '----------------------------------------------------------------------------' |
1081 | |
1082 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
1083 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
1084 | [debug] Found home "/home/me/MyApp" |
1085 | [debug] Loaded Config "/home/me/myapp.yml" |
1086 | [debug] Loaded components: |
1087 | .-----------------------------------------------------------------+----------. |
1088 | | Class | Type | |
1089 | +-----------------------------------------------------------------+----------+ |
1090 | | MyApp::Controller::Books | instance | |
1091 | | MyApp::Controller::Root | instance | |
1092 | | MyApp::Model::MyAppDB | instance | |
1093 | | MyApp::Model::MyAppDB::Author | class | |
1094 | | MyApp::Model::MyAppDB::Book | class | |
1095 | | MyApp::Model::MyAppDB::BookAuthor | class | |
1096 | | MyApp::View::TT | instance | |
1097 | '-----------------------------------------------------------------+----------' |
1098 | |
1099 | [debug] Loaded Private actions: |
1100 | .----------------------+--------------------------------------+--------------. |
1101 | | Private | Class | Method | |
1102 | +----------------------+--------------------------------------+--------------+ |
1103 | | /default | MyApp::Controller::Root | default | |
1104 | | /end | MyApp::Controller::Root | end | |
1105 | | /books/index | MyApp::Controller::Books | index | |
1106 | | /books/list | MyApp::Controller::Books | list | |
1107 | '----------------------+--------------------------------------+--------------' |
1108 | |
1109 | [debug] Loaded Path actions: |
1110 | .-------------------------------------+--------------------------------------. |
1111 | | Path | Private | |
1112 | +-------------------------------------+--------------------------------------+ |
1113 | | /books/list | /books/list | |
1114 | '-------------------------------------+--------------------------------------' |
1115 | |
1116 | [info] MyApp powered by Catalyst 5.7002 |
1117 | You can connect to your server at http://localhost:3000 |
1118 | |
1119 | Some things you should note in the output above: |
1120 | |
1121 | =over 4 |
1122 | |
1123 | =item * |
1124 | |
1125 | Catalyst::Model::DBIC::Schema took our C<MyAppDB::Book> and made it |
1126 | C<MyApp::Model::MyAppDB::Book> (and similar actions were performed on |
1127 | C<MyAppDB::Author> and C<MyAppDB::BookAuthor>). |
1128 | |
1129 | =item * |
1130 | |
1131 | The "list" action in our Books controller showed up with a path of |
1132 | C</books/list>. |
1133 | |
1134 | =back |
1135 | |
1136 | Point your browser to L<http://localhost:3000> and you should still get |
1137 | the Catalyst welcome page. |
1138 | |
1139 | Next, to view the book list, change the URL in your browser to |
1140 | L<http://localhost:3000/books/list>. You should get a list of the five |
1141 | books loaded by the C<myapp01.sql> script above, with TTSite providing |
1142 | the formatting for the very simple output we generated in our template. |
1143 | The count and space-separated list of author last names appear on the |
1144 | end of each row. |
1145 | |
1146 | Also notice in the output of the C<script/myapp_server.pl> that DBIC |
1147 | used the following SQL to retrieve the data: |
1148 | |
1149 | SELECT me.id, me.title, me.rating FROM books me |
1150 | |
1151 | Along with a list of the following commands to retrieve the authors for |
1152 | each book (the lines have been "word wrapped" here to improve |
1153 | legibility): |
1154 | |
1155 | SELECT author.id, author.first_name, author.last_name |
1156 | FROM book_authors me |
1157 | JOIN authors author ON ( author.id = me.author_id ) |
1158 | WHERE ( me.book_id = ? ): `1' |
1159 | |
1160 | You should see 5 such lines of debug output as DBIC fetches the author |
1161 | information for each book. |
1162 | |
1163 | |
1164 | =head1 USING THE DEFAULT TEMPLATE NAME |
1165 | |
1166 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1167 | same name as your controller action, allowing you to save the step of |
1168 | manually specifying the template name in each action. For example, this |
1169 | would allow us to remove the |
1170 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1171 | C<list> action in the Books controller. Open |
1172 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1173 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1174 | has changed): |
1175 | |
1176 | =head2 list |
1177 | |
1178 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1179 | |
1180 | =cut |
1181 | |
1182 | sub list : Local { |
1183 | # Retrieve the usual perl OO '$self' for this object. $c is the Catalyst |
1184 | # 'Context' that's used to 'glue together' the various components |
1185 | # that make up the application |
1186 | my ($self, $c) = @_; |
1187 | |
1188 | # Retrieve all of the book records as book model objects and store in the |
1189 | # stash where they can be accessed by the TT template |
1190 | $c->stash->{books} = [$c->model('MyAppDB::Book')->all]; |
1191 | |
1192 | # Set the TT template to use. You will almost always want to do this |
1193 | # in your action methods (actions methods respond to user input in |
1194 | # your controllers). |
1195 | #$c->stash->{template} = 'books/list.tt2'; |
1196 | } |
1197 | |
1198 | C<Catalyst::View::TT> defaults to looking for a template with no |
1199 | extension. In our case, we need to override this to look for an |
1200 | extension of C<.tt2>. Open C<lib/MyApp/View/TT.pm> and add the |
1201 | C<TEMPLATE_EXTENSION> definition as follows: |
1202 | |
1203 | __PACKAGE__->config({ |
1204 | CATALYST_VAR => 'Catalyst', |
1205 | INCLUDE_PATH => [ |
1206 | MyApp->path_to( 'root', 'src' ), |
1207 | MyApp->path_to( 'root', 'lib' ) |
1208 | ], |
1209 | PRE_PROCESS => 'config/main', |
1210 | WRAPPER => 'site/wrapper', |
1211 | ERROR => 'error.tt2', |
1212 | TIMER => 0, |
1213 | TEMPLATE_EXTENSION => '.tt2', |
1214 | }); |
1215 | |
1216 | You should now be able to restart the development server as per the |
1217 | previous section and access the L<http://localhost:3000/books/list> |
1218 | as before. |
1219 | |
1220 | B<NOTE:> Please note that if you use the default template technique, |
1221 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
1222 | the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and |
1223 | Part 8 of the Tutorial). |
1224 | |
1225 | |
1226 | =head1 RETURN TO A MANUALLY-SPECIFIED TEMPLATE |
1227 | |
1228 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1229 | later in the tutorial, you should remove the comment from the |
1230 | statement in C<sub list>: |
1231 | |
1232 | $c->stash->{template} = 'books/list.tt2'; |
1233 | |
1234 | Then delete the C<TEMPLATE_EXTENSION> line in |
1235 | C<lib/MyApp/View/TT.pm>. |
1236 | |
1237 | You should then be able to restart the development server and |
1238 | access L<http://localhost:3000/books/list> in the same manner as |
1239 | with earlier sections. |
1240 | |
1241 | |
1242 | =head1 AUTHOR |
1243 | |
1244 | Kennedy Clark, C<hkclark@gmail.com> |
1245 | |
1246 | Please report any errors, issues or suggestions to the author. The |
1247 | most recent version of the Catalyst Tutorial can be found at |
d712b826 |
1248 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>. |
d442cc9f |
1249 | |
1250 | Copyright 2006, Kennedy Clark, under Creative Commons License |
1251 | (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>). |
1252 | |