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1 | =head1 NAME |
2 | |
3 | Catalyst::Manual::Tutorial::MoreCatalystBasics - Catalyst Tutorial - Part 3: More Catalyst Application Development Basics |
4 | |
5 | |
6 | =head1 OVERVIEW |
7 | |
8 | This is B<Part 3 of 10> 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 | L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics> |
21 | |
22 | =item 3 |
23 | |
24 | B<More Catalyst Basics> |
25 | |
26 | =item 4 |
27 | |
28 | L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD> |
29 | |
30 | =item 5 |
31 | |
32 | L<Authentication|Catalyst::Manual::Tutorial::Authentication> |
33 | |
34 | =item 6 |
35 | |
36 | L<Authorization|Catalyst::Manual::Tutorial::Authorization> |
37 | |
38 | =item 7 |
39 | |
40 | L<Debugging|Catalyst::Manual::Tutorial::Debugging> |
41 | |
42 | =item 8 |
43 | |
44 | L<Testing|Catalyst::Manual::Tutorial::Testing> |
45 | |
46 | =item 9 |
47 | |
48 | L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD> |
49 | |
50 | =item 10 |
51 | |
52 | L<Appendices|Catalyst::Manual::Tutorial::Appendices> |
53 | |
54 | =back |
55 | |
56 | |
57 | =head1 DESCRIPTION |
58 | |
59 | This part of the tutorial builds on the work done in Part 2 to explore |
60 | some features that are more typical of "real world" web applications. |
61 | From this part of the tutorial onward, we will be building a simple |
62 | book database application. Although the application will be too |
63 | limited to be of use to anyone, it should provide a basic environment |
64 | where we can explore a variety of features used in virtually all web |
65 | applications. |
66 | |
67 | You can checkout the source code for this example from the catalyst |
68 | subversion repository as per the instructions in |
69 | L<Catalyst::Manual::Tutorial::Intro> |
70 | |
71 | |
72 | =head1 CREATE A NEW APPLICATION |
73 | |
74 | The remainder of the tutorial will build an application call C<MyApp>. |
75 | Use the Catalyst C<catalyst.pl> script to initialize the framework for |
76 | an application called C<MyApp> (make sure you aren't still inside the |
77 | directory of the C<Hello> application from the previous part of the |
78 | tutorial): |
79 | |
80 | $ catalyst.pl MyApp |
81 | created "MyApp" |
82 | created "MyApp/script" |
83 | created "MyApp/lib" |
84 | created "MyApp/root" |
85 | ... |
86 | created "MyApp/script/myapp_create.pl" |
87 | $ cd MyApp |
88 | |
89 | This creates a similar skeletal structure to what we saw in Part 2 of |
90 | the tutorial, except with C<MyApp> or C<myapp> substituted for |
91 | C<Hello> and C<hello>. |
92 | |
93 | |
94 | =head1 EDIT THE LIST OF CATALYST PLUGINS |
95 | |
96 | One of the greatest benefits of Catalyst is that it has such a large |
97 | library of plugins available. Plugins are used to seamlessly integrate |
98 | existing Perl modules into the overall Catalyst framework. In general, |
99 | they do this by adding additional methods to the C<context> object |
100 | (generally written as C<$c>) that Catalyst passes to every component |
101 | throughout the framework. |
102 | |
103 | By default, Catalyst enables three plugins/flags: |
104 | |
105 | =over 4 |
106 | |
107 | =item * |
108 | |
109 | C<-Debug> Flag |
110 | |
111 | Enables the Catalyst debug output you saw when we started the |
112 | C<script/myapp_server.pl> development server earlier. You can remove |
113 | this plugin when you place your application into production. |
114 | |
115 | As you may have noticed, C<-Debug> is not a plugin, but a I<flag>. |
116 | Although most of the items specified on the C<use Catalyst> line of your |
117 | application class will be plugins, Catalyst supports a limited number of |
118 | flag options (of these, C<-Debug> is the most common). See the |
119 | documentation for C<Catalyst.pm> to get details on other flags |
120 | (currently C<-Engine>, C<-Home>, and C<-Log>). |
121 | |
122 | If you prefer, you can use the C<$c-E<gt>debug> method to enable debug |
123 | messages. |
124 | |
125 | B<TIP>: Depending on your needs, it can be helpful to permanently |
126 | remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option |
127 | to C<script/myapp_server.pl> to re-enable it just for the development |
128 | server. We will not be using that approach in the tutorial, but feel |
129 | free to make use of it in your own projects. |
130 | |
131 | =item * |
132 | |
133 | L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> |
134 | |
135 | C<ConfigLoader> provides an automatic way to load configurable |
136 | parameters for your application from a central YAML file (versus having |
137 | the values hard-coded inside your Perl modules). If you have not been |
138 | exposed to YAML before, it is a human-readable data serialization format |
139 | that can be used to read (and write) values to/from text files. We will |
140 | see how to use this feature of Catalyst during the authentication and |
141 | authorization sections (Part 5 and Part 6). |
142 | |
143 | =item * |
144 | |
145 | L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple> |
146 | |
147 | C<Static::Simple> provides an easy method of serving static content such |
148 | as images and CSS files under the development server. |
149 | |
150 | =back |
151 | |
152 | To modify the list of plugins, edit C<lib/MyApp.pm> (this file is |
153 | generally referred to as your I<application class>) and delete the line |
154 | with: |
155 | |
156 | use Catalyst qw/-Debug ConfigLoader Static::Simple/; |
157 | |
158 | Replace it with: |
159 | |
160 | use Catalyst qw/ |
161 | -Debug |
162 | ConfigLoader |
163 | Static::Simple |
164 | |
165 | StackTrace |
166 | /; |
167 | |
168 | This tells Catalyst to start using one new plugin: |
169 | |
170 | =over 4 |
171 | |
172 | =item * |
173 | |
174 | L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace> |
175 | |
176 | Adds a stack trace to the standard Catalyst "debug screen" (this is the |
177 | screen Catalyst sends to your browser when an error occurs). |
178 | |
179 | Note: L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your |
180 | browser, not in the console window from which you're running your |
181 | application, which is where logging output usually goes. |
182 | |
183 | =back |
184 | |
185 | Note that when specifying plugins on the C<use Catalyst> line, you can |
186 | omit C<Catalyst::Plugin::> from the name. Additionally, you can spread |
187 | the plugin names across multiple lines as shown here, or place them all |
188 | on one (or more) lines as with the default configuration. |
189 | |
190 | |
191 | =head1 CREATE A CATALYST CONTROLLER |
192 | |
193 | As discussed earlier, controllers are where you write methods that |
194 | interact with user input. Typically, controller methods respond to |
195 | C<GET> and C<POST> messages from the user's web browser. |
196 | |
197 | Use the Catalyst C<create> script to add a controller for book-related |
198 | actions: |
199 | |
200 | $ script/myapp_create.pl controller Books |
201 | exists "/home/me/MyApp/script/../lib/MyApp/Controller" |
202 | exists "/home/me/MyApp/script/../t" |
203 | created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm" |
204 | created "/home/me/MyApp/script/../t/controller_Books.t" |
205 | |
206 | Then edit C<lib/MyApp/Controller/Books.pm> and add the following method |
207 | to the controller: |
208 | |
209 | =head2 list |
210 | |
211 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
212 | |
213 | =cut |
214 | |
215 | sub list : Local { |
216 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
217 | # 'Context' that's used to 'glue together' the various components |
218 | # that make up the application |
219 | my ($self, $c) = @_; |
220 | |
221 | # Retrieve all of the book records as book model objects and store in the |
222 | # stash where they can be accessed by the TT template |
223 | $c->stash->{books} = [$c->model('MyAppDB::Books')->all]; |
224 | |
225 | # Set the TT template to use. You will almost always want to do this |
226 | # in your action methods (action methods respond to user input in |
227 | # your controllers). |
228 | $c->stash->{template} = 'books/list.tt2'; |
229 | } |
230 | |
231 | B<Note:> This won't actually work yet since you haven't set up your |
232 | model yet. |
233 | |
234 | B<Note:> Programmers experienced with object-oriented Perl should |
235 | recognize C<$self> as a reference to the object where this method was |
236 | called. On the other hand, C<$c> will be new to many Perl programmers |
237 | who have not used Catalyst before (it's sometimes written as |
238 | C<$context>). The Context object is automatically passed to all |
239 | Catalyst components. It is used to pass information between |
240 | components and provide access to Catalyst and plugin functionality. |
241 | |
242 | B<TIP>: You may see the C<$c-E<gt>model('MyAppDB::Book')> used above |
243 | written as C<$c-E<gt>model('MyAppDB')-E<gt>resultset('Book)>. The two |
244 | are equivalent. |
245 | |
246 | B<Note:> Catalyst actions are regular Perl methods, but they make use |
247 | of Nicholas Clark's C<attributes> module (that's the C<: Local> next |
248 | to the C<sub list> in the code above) to provide additional |
249 | information to the Catalyst dispatcher logic. Many newer Catalyst |
250 | applications are switching to the use of "Literal" C<: Path> actions |
251 | and C<Args> attribute in lieu of C<: Local> and C<: Private>. For |
252 | example, C<sub any_method : Path Args(0)> can be used instead of |
253 | C<sub index :Private> (because no path was supplied to C<Path> it |
254 | matches the "empty" URL in the namespace of that module... the same |
255 | thing C<sub index> would do) or C<sub list : Path('list') Args(0)> |
256 | could be used instead of the C<sub list : Local> above (the C<list> |
257 | argument to C<Path> would make it match on the URL C<list> under |
258 | C<books>, the namespace of the current module). See "Action Types" in |
259 | L<Catalyst::Manual::Intro|Catalyst::Manual::Intro> as well as Part 5 |
260 | of this tutorial (Authentication) for additional information. Another |
261 | popular but more advanced feature is C<Chained> actions that allow a |
262 | single URL to "chain together" multiple action method calls, each with |
263 | an appropriate number of arguments (see |
264 | L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> |
265 | for details). |
266 | |
267 | |
268 | =head1 CATALYST VIEWS |
269 | |
270 | As mentioned in Part 2 of the tutorial, views are where you render |
271 | output, typically for display in the user's web browser, but also |
272 | possibly using other display output- generation systems. As with |
273 | virtually every aspect of Catalyst, options abound when it comes to |
274 | the specific view technology you adopt inside your application. |
275 | However, most Catalyst applications use the Template Toolkit, known as |
276 | TT (for more information on TT, see L<http://www.template- |
277 | toolkit.org>). Other popular view technologies include Mason |
278 | (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and |
279 | L<HTML::Template|HTML::Template> (L<http://html- |
280 | template.sourceforge.net>). |
281 | |
282 | =head2 Create a Catalyst View Using C<TTSite> |
283 | |
284 | When using TT for the Catalyst view, there are two main helper scripts: |
285 | |
286 | =over 4 |
287 | |
288 | =item * |
289 | |
290 | L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT> |
291 | |
292 | =item * |
293 | |
294 | L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite> |
295 | |
296 | =back |
297 | |
298 | Both are similar, but C<TT> merely creates the C<lib/MyApp/View/TT.pm> |
299 | file and leaves the creation of any hierarchical template organization |
300 | entirely up to you. (It also creates a C<t/view_TT.t> file for testing; |
301 | test cases will be discussed in Part 8). The C<TTSite> helper creates a |
302 | modular and hierarchical view layout with separate Template Toolkit (TT) |
303 | files for common header and footer information, configuration values, a |
304 | CSS stylesheet, and more. |
305 | |
306 | While TTSite is useful to bootstrap a project, we recommend that |
307 | unless you know what you're doing or want to pretty much use the |
308 | supplied templates as is, that you use the plain Template Toolkit view |
309 | when starting a project from scratch. This is because TTSite can be |
310 | tricky to customize. Additionally TT contains constructs that you |
311 | need to learn yourself if you're going to be a serious user of TT. |
312 | Our experience suggests that you're better off learning these from |
313 | scratch. We use TTSite here precisely because it is useful for |
314 | bootstrap/prototype purposes. |
315 | |
316 | Enter the following command to enable the C<TTSite> style of view |
317 | rendering for this tutorial: |
318 | |
319 | $ script/myapp_create.pl view TT TTSite |
320 | exists "/home/me/MyApp/script/../lib/MyApp/View" |
321 | exists "/home/me/MyApp/script/../t" |
322 | created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm" |
323 | created "/home/me/MyApp/script/../root/lib" |
324 | ... |
325 | created "/home/me/MyApp/script/../root/src/ttsite.css" |
326 | |
327 | This puts a number of files in the C<root/lib> and C<root/src> |
328 | directories that can be used to customize the look and feel of your |
329 | application. Also take a look at C<lib/MyApp/View/TT.pm> for config |
330 | values set by the C<TTSite> helper. |
331 | |
332 | B<TIP>: Note that TTSite does one thing that could confuse people who |
333 | are used to the normal C<TT> Catalyst view: it redefines the Catalyst |
334 | context object in templates from its usual C<c> to C<Catalyst>. When |
335 | looking at other Catalyst examples, remember that they almost always use |
336 | C<c>. Note that Catalyst and TT I<do not complain> when you use the |
337 | wrong name to access the context object...TT simply outputs blanks for |
338 | that bogus logic (see next tip to change this behavior with TT C<DEBUG> |
339 | options). Finally, be aware that this change in name I<only> |
340 | applies to how the context object is accessed inside your TT templates; |
341 | your controllers will continue to use C<$c> (or whatever name you use |
342 | when fetching the reference from C<@_> inside your methods). (You can |
343 | change back to the "default" behavior be removing the C<CATALYST_VAR> |
344 | line from C<lib/MyApp/View/TT.pm>, but you will also have to edit |
345 | C<root/lib/config/main> and C<root/lib/config/url>. If you do this, be |
346 | careful not to have a collision between your own C<c> variable and the |
347 | Catalyst C<c> variable.) |
348 | |
349 | B<TIP>: When troubleshooting TT it can be helpful to enable variable |
350 | C<DEBUG> options. You can do this in a Catalyst environment by adding |
351 | a C<DEBUG> line to the C<__PACKAGE__->config> declaration in |
352 | C<lib/MyApp/View/TT.pm>: |
353 | |
354 | __PACKAGE__->config({ |
355 | CATALYST_VAR => 'Catalyst', |
356 | ... |
357 | DEBUG => 'undef', |
358 | ... |
359 | }); |
360 | |
361 | B<Note:> C<__PACKAGE__> is just a shorthand way of referencing the name |
362 | of the package where it is used. Therefore, in C<TT.pm>, |
363 | C<__PACKAGE__> is equivalent to C<TT>. |
364 | |
365 | There are a variety of options you can use, such as 'undef', 'all', |
366 | 'service', 'context', 'parser', 'provider', and 'service'. See |
367 | L<Template::Constants> for more information (remove the C<DEBUG_> |
368 | portion of the name shown in the TT docs and convert to lower case |
369 | for use inside Catalyst). |
370 | |
371 | B<NOTE:> B<Please be sure to disable TT debug options before |
372 | continuing the tutorial> (especially the 'undef' option -- leaving |
373 | this enabled will conflict with several of the conventions used |
374 | by this tutorial and TTSite to leave some variables undefined |
375 | on purpose). |
376 | |
377 | |
378 | =head2 Globally Customize Every View |
379 | |
380 | When using TTSite, files in the subdirectories of C<root/lib> can be |
381 | used to make changes that will appear in every view. For example, to |
382 | display optional status and error messages in every view, edit |
383 | C<root/lib/site/layout>, updating it to match the following (the two HTML |
384 | C<span> elements are new): |
385 | |
386 | <div id="header">[% PROCESS site/header %]</div> |
387 | |
388 | <div id="content"> |
389 | <span class="message">[% status_msg %]</span> |
390 | <span class="error">[% error_msg %]</span> |
391 | [% content %] |
392 | </div> |
393 | |
394 | <div id="footer">[% PROCESS site/footer %]</div> |
395 | |
396 | If we set either message in the Catalyst stash (e.g., |
397 | C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it will |
398 | be displayed whenever any view used by that request is rendered. The |
399 | C<message> and C<error> CSS styles are automatically defined in |
400 | C<root/src/ttsite.css> and can be customized to suit your needs. |
401 | |
402 | B<Note:> The Catalyst stash only lasts for a single HTTP request. If |
403 | you need to retain information across requests you can use |
404 | L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use |
405 | Catalyst sessions in the Authentication part of the tutorial). |
406 | |
407 | |
408 | =head2 Create a TT Template Page |
409 | |
410 | To add a new page of content to the TTSite view hierarchy, just create a |
411 | new C<.tt2> file in C<root/src>. Only include HTML markup that goes |
412 | inside the HTML <body> and </body> tags, TTSite will use the contents of |
413 | C<root/lib/site> to add the top and bottom. |
414 | |
415 | First create a directory for book-related TT templates: |
416 | |
417 | $ mkdir root/src/books |
418 | |
419 | Then create C<root/src/books/list.tt2> in your editor and enter: |
420 | |
421 | [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%] |
422 | [% # see this "chomping" in your browser because HTML ignores blank lines, but -%] |
423 | [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%] |
424 | [%- # optional, but both the beginning and the ending TT tags support chomping. -%] |
425 | |
426 | [% # Provide a title to root/lib/site/header -%] |
427 | [% META title = 'Book List' -%] |
428 | |
429 | <table> |
430 | <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr> |
431 | [% # Display each book in a table row %] |
432 | [% FOREACH book IN books -%] |
433 | <tr> |
434 | <td>[% book.title %]</td> |
435 | <td>[% book.rating %]</td> |
436 | </tr> |
437 | [% END -%] |
438 | </table> |
439 | |
440 | As indicated by the inline comments above, the C<META title> line uses |
441 | TT's META feature to provide a title to C<root/lib/site/header>. |
442 | Meanwhile, the outer C<FOREACH> loop iterates through each C<book> model |
443 | object and prints the C<title> and C<rating> fields. An inner |
444 | C<FOREACH> loop prints the last name of each author in a comma-separated |
445 | list within a single table cell. |
446 | |
447 | If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT |
448 | code. TT supports a wide variety of directives for "calling" other |
449 | files, looping, conditional logic, etc. In general, TT simplifies the |
450 | usual range of Perl operators down to the single dot (C<.>) operator. |
451 | This applies to operations as diverse as method calls, hash lookups, and |
452 | list index values (see |
453 | L<http://www.template-toolkit.org/docs/default/Manual/Variables.html> |
454 | for details and examples). In addition to the usual C<Template> module |
455 | Pod documentation, you can access the TT manual at |
456 | L<http://www.template-toolkit.org/docs/default/>. |
457 | |
458 | B<NOTE>: The C<TTSite> helper creates several TT files using an |
459 | extension of C<.tt2>. Most other Catalyst and TT examples use an |
460 | extension of C<.tt>. You can use either extension (or no extension at |
461 | all) with TTSite and TT, just be sure to use the appropriate extension |
462 | for both the file itself I<and> the C<$c-E<gt>stash-E<gt>{template} = |
463 | ...> line in your controller. This document will use C<.tt2> for |
464 | consistency with the files already created by the C<TTSite> helper. |
465 | |
466 | |
467 | =head1 CREATE A SQLITE DATABASE |
468 | |
469 | In this step, we make a text file with the required SQL commands to |
470 | create a database table and load some sample data. Open C<myapp01.sql> |
471 | in your editor and enter: |
472 | |
473 | -- |
474 | -- Create a very simple database to hold book and author information |
475 | -- |
476 | CREATE TABLE books ( |
477 | id INTEGER PRIMARY KEY, |
478 | title TEXT , |
479 | rating INTEGER |
480 | ); |
481 | -- 'book_authors' is a many-to-many join table between books & authors |
482 | CREATE TABLE book_authors ( |
483 | book_id INTEGER, |
484 | author_id INTEGER, |
485 | PRIMARY KEY (book_id, author_id) |
486 | ); |
487 | CREATE TABLE authors ( |
488 | id INTEGER PRIMARY KEY, |
489 | first_name TEXT, |
490 | last_name TEXT |
491 | ); |
492 | --- |
493 | --- Load some sample data |
494 | --- |
495 | INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5); |
496 | INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5); |
497 | INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4); |
498 | INSERT INTO books VALUES (4, 'Perl Cookbook', 5); |
499 | INSERT INTO books VALUES (5, 'Designing with Web Standards', 5); |
500 | INSERT INTO authors VALUES (1, 'Greg', 'Bastien'); |
501 | INSERT INTO authors VALUES (2, 'Sara', 'Nasseh'); |
502 | INSERT INTO authors VALUES (3, 'Christian', 'Degu'); |
503 | INSERT INTO authors VALUES (4, 'Richard', 'Stevens'); |
504 | INSERT INTO authors VALUES (5, 'Douglas', 'Comer'); |
505 | INSERT INTO authors VALUES (6, 'Tom', 'Christiansen'); |
506 | INSERT INTO authors VALUES (7, 'Nathan', 'Torkington'); |
507 | INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman'); |
508 | INSERT INTO book_authors VALUES (1, 1); |
509 | INSERT INTO book_authors VALUES (1, 2); |
510 | INSERT INTO book_authors VALUES (1, 3); |
511 | INSERT INTO book_authors VALUES (2, 4); |
512 | INSERT INTO book_authors VALUES (3, 5); |
513 | INSERT INTO book_authors VALUES (4, 6); |
514 | INSERT INTO book_authors VALUES (4, 7); |
515 | INSERT INTO book_authors VALUES (5, 8); |
516 | |
517 | B<TIP>: See Appendix 1 for tips on removing the leading spaces when |
518 | cutting and pasting example code from POD-based documents. |
519 | |
520 | Then use the following command to build a C<myapp.db> SQLite database: |
521 | |
522 | $ sqlite3 myapp.db < myapp01.sql |
523 | |
524 | If you need to create the database more than once, you probably want to |
525 | issue the C<rm myapp.db> command to delete the database before you use |
526 | the C<sqlite3 myapp.db < myapp01.sql> command. |
527 | |
528 | Once the C<myapp.db> database file has been created and initialized, you |
529 | can use the SQLite command line environment to do a quick dump of the |
530 | database contents: |
531 | |
532 | $ sqlite3 myapp.db |
533 | SQLite version 3.4.2 |
534 | Enter ".help" for instructions |
535 | sqlite> select * from books; |
536 | 1|CCSP SNRS Exam Certification Guide|5 |
537 | 2|TCP/IP Illustrated, Volume 1|5 |
538 | 3|Internetworking with TCP/IP Vol.1|4 |
539 | 4|Perl Cookbook|5 |
540 | 5|Designing with Web Standards|5 |
541 | sqlite> .q |
542 | $ |
543 | |
544 | Or: |
545 | |
546 | $ sqlite3 myapp.db "select * from books" |
547 | 1|CCSP SNRS Exam Certification Guide|5 |
548 | 2|TCP/IP Illustrated, Volume 1|5 |
549 | 3|Internetworking with TCP/IP Vol.1|4 |
550 | 4|Perl Cookbook|5 |
551 | 5|Designing with Web Standards|5 |
552 | |
553 | As with most other SQL tools, if you are using the full "interactive" |
554 | environment you need to terminate your SQL commands with a ";" (it's not |
555 | required if you do a single SQL statement on the command line). Use |
556 | ".q" to exit from SQLite from the SQLite interactive mode and return to |
557 | your OS command prompt. |
558 | |
559 | |
560 | =head1 DATABASE ACCESS WITH C<DBIx::Class> |
561 | |
562 | Catalyst can be used with virtually any form of persistent datastore |
563 | available via Perl. For example, |
564 | L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to |
565 | easily access databases through the traditional Perl C<DBI> interface. |
566 | However, most Catalyst applications use some form of ORM technology to |
567 | automatically create and save model objects as they are used. Although |
568 | Tony Bowden's L<Class::DBI|Class::DBI> has been a popular choice |
569 | in the past, Matt Trout's L<DBIx::Class|DBIx::Class> (abbreviated |
570 | as "DBIC") has rapidly emerged as the Perl-based ORM technology of choice. |
571 | Most new Catalyst applications rely on DBIC, as will this tutorial. |
572 | |
573 | =head2 Create a Dynamic DBIC Model |
574 | |
575 | Use the C<create=dynamic> model helper option to build a model that |
576 | dynamically reads your database structure every time the application |
577 | starts: |
578 | |
579 | $ script/myapp_create.pl model MyAppDB DBIC::Schema MyApp::Schema::MyAppDB create=dynamic dbi:SQLite:myapp.db |
580 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
581 | exists "/home/me/MyApp/script/../t" |
582 | created "/home/me/MyApp/script/../lib/MyApp/Schema" |
583 | created "/home/me/MyApp/script/../lib/MyApp/Schema/MyAppDB.pm" |
584 | created "/home/me/MyApp/script/../lib/MyApp/Model/MyAppDB.pm" |
585 | created "/home/me/MyApp/script/../t/model_MyAppDB.t" |
586 | |
587 | |
588 | C<MyAppDB> is the name of the model class to be created by the helper in |
589 | C<lib/MyApp/Model> (Catalyst has a separate directory under C<lib/MyApp> |
590 | for each of the three parts of MVC: C<Model>, C<View>, and C<Controller> |
591 | [although older Catalyst applications often use the directories C<M>, |
592 | C<V>, and C<C>]). C<DBIC::Schema> is the type of the model to create. |
593 | C<MyApp::Schema::MyAppDB> is the name of the DBIC schema file written to |
594 | C<lib/MyApp/Schema/MyAppDB.pm>. Because we specified C<create=dynamic> |
595 | to the helper, it use L<DBIx::Class::Schema::Loader> to dynamically load |
596 | the schema information from the database every time the application |
597 | starts. And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect |
598 | string for use with SQLite. |
599 | |
600 | B<NOTE>: Although the C<create=dynamic> option to the DBIC helper |
601 | makes for a nifty demonstration, is not suitable for real world |
602 | applications. Moreover, it may not be supported in future versions of |
603 | DBIC. After this demonstration, please use the C<create=static> |
604 | option that we switch to below. |
605 | |
606 | |
607 | =head1 RUN THE APPLICATION |
608 | |
609 | First, let's enable an environment variable option that causes |
610 | DBIx::Class to dump the SQL statements it's using to access the database |
611 | (this option can provide extremely helpful troubleshooting information): |
612 | |
613 | $ export DBIC_TRACE=1 |
614 | |
615 | This assumes you are using BASH as your shell -- adjust accordingly if |
616 | you are using a different shell (for example, under tcsh, use |
617 | C<setenv DBIC_TRACE 1>). |
618 | |
619 | B<NOTE>: You can also set this in your code using |
620 | C<$class-E<gt>storage-E<gt>debug(1);>. See |
621 | L<DBIx::Class::Manual::Troubleshooting> for details (including options |
622 | to log to file instead of displaying to the Catalyst development server |
623 | log). |
624 | |
625 | Then run the Catalyst "demo server" script: |
626 | |
627 | $ script/myapp_server.pl |
628 | |
629 | Your development server log output should display something like: |
630 | |
631 | $script/myapp_server.pl |
632 | [debug] Debug messages enabled |
633 | [debug] Loaded plugins: |
634 | .----------------------------------------------------------------------------. |
635 | | Catalyst::Plugin::ConfigLoader 0.17 | |
636 | | Catalyst::Plugin::StackTrace 0.06 | |
637 | | Catalyst::Plugin::Static::Simple 0.20 | |
638 | '----------------------------------------------------------------------------' |
639 | |
640 | [debug] Loaded dispatcher "Catalyst::Dispatcher" |
641 | [debug] Loaded engine "Catalyst::Engine::HTTP" |
642 | [debug] Found home "/home/me/MyApp" |
643 | [debug] Loaded Config "/home/me/MyApp/myapp.yml" |
644 | [debug] Loaded components: |
645 | .-----------------------------------------------------------------+----------. |
646 | | Class | Type | |
647 | +-----------------------------------------------------------------+----------+ |
648 | | MyApp::Controller::Books | instance | |
649 | | MyApp::Controller::Root | instance | |
650 | | MyApp::Model::MyAppDB | instance | |
651 | | MyApp::Model::MyAppDB::Authors | class | |
652 | | MyApp::Model::MyAppDB::BookAuthors | class | |
653 | | MyApp::Model::MyAppDB::Books | class | |
654 | | MyApp::View::TT | instance | |
655 | '-----------------------------------------------------------------+----------' |
656 | |
657 | [debug] Loaded Private actions: |
658 | .----------------------+--------------------------------------+--------------. |
659 | | Private | Class | Method | |
660 | +----------------------+--------------------------------------+--------------+ |
661 | | /default | MyApp::Controller::Root | default | |
662 | | /end | MyApp::Controller::Root | end | |
663 | | /books/index | MyApp::Controller::Books | index | |
664 | | /books/list | MyApp::Controller::Books | list | |
665 | '----------------------+--------------------------------------+--------------' |
666 | |
667 | [debug] Loaded Path actions: |
668 | .-------------------------------------+--------------------------------------. |
669 | | Path | Private | |
670 | +-------------------------------------+--------------------------------------+ |
671 | | /books/list | /books/list | |
672 | '-------------------------------------+--------------------------------------' |
673 | |
674 | [info] MyApp powered by Catalyst 5.7011 |
675 | You can connect to your server at http://localhost:3000 |
676 | |
677 | B<NOTE>: Be sure you run the C<script/myapp_server.pl> command from |
678 | the 'base' directory of your application, not inside the C<script> |
679 | directory itself or it will not be able to locate the C<myapp.db> |
680 | database file. You can use a fully qualified or a relative path to |
681 | locate the database file, but we did not specify that when we ran the |
682 | model helper earlier. |
683 | |
684 | Some things you should note in the output above: |
685 | |
686 | =over 4 |
687 | |
688 | =item * |
689 | |
690 | Catalyst::Model::DBIC::Schema dynamically created three model classes, |
691 | one to represent each of the three tables in our database |
692 | (C<MyApp::Model::MyAppDB::Authors>, C<MyApp::Model::MyAppDB::BookAuthors>, |
693 | and C<MyApp::Model::MyAppDB::Books>). |
694 | |
695 | =item * |
696 | |
697 | The "list" action in our Books controller showed up with a path of |
698 | C</books/list>. |
699 | |
700 | =back |
701 | |
702 | Point your browser to L<http://localhost:3000> and you should still get |
703 | the Catalyst welcome page. |
704 | |
705 | Next, to view the book list, change the URL in your browser to |
706 | L<http://localhost:3000/books/list>. You should get a list of the five |
707 | books loaded by the C<myapp01.sql> script above, with TTSite providing |
708 | the formatting for the very simple output we generated in our template. |
709 | The rating for each book should appear on each row. |
710 | |
711 | Also notice in the output of the C<script/myapp_server.pl> that DBIC |
712 | used the following SQL to retrieve the data: |
713 | |
714 | SELECT me.id, me.title, me.rating FROM books me |
715 | |
716 | because we enabled DBIC_TRACE. |
717 | |
718 | You now the beginnings of a simple but workable web application. |
719 | Continue on to future sections and we will develop the application |
720 | more fully. |
721 | |
722 | |
723 | =head1 A STATIC DATABASE MODEL WITH C<DBIx::Class> |
724 | |
725 | =head2 Create Static DBIC Schema Files |
726 | |
727 | Unlike the previous section where we had DBIC automatically discover the |
728 | structure of the database every time the application started, here we |
729 | will use static schema files for more control. This is typical of most |
730 | "real world" applications. |
731 | |
732 | One option would be to create a separate schema file for each table in |
733 | the database, however, lets use the same L<DBIx::Class::Schema::Loader> |
734 | used earlier with C<create=dynamic> to build the static files for us. |
735 | First, lets remove the schema file created in Part 2: |
736 | |
737 | $ rm lib/MyApp/Schema/MyAppDB.pm |
738 | |
739 | Now regenerate the schema using the C<create=static> option: |
740 | |
741 | $ script/myapp_create.pl model MyAppDB DBIC::Schema MyApp::Schema::MyAppDB create=static dbi:SQLite:myapp.db |
742 | exists "/home/me/MyApp/script/../lib/MyApp/Model" |
743 | exists "/home/me/MyApp/script/../t" |
744 | Dumping manual schema for MyApp::Schema::MyAppDB to directory /home/me/MyApp/script/../lib ... |
745 | Schema dump completed. |
746 | exists "/home/me/MyApp/script/../lib/MyApp/Model/MyAppDB.pm" |
747 | |
748 | We could have also deleted C<lib/MyApp/Model/MyAppDB.pm>, but it would |
749 | have regenerated the same file (note the C<exists> in the output above). |
750 | If you take a look at C<lib/MyApp/Model/MyAppDB.pm>, it simply contains |
751 | a reference to the actual schema file in C<lib/MyApp/Schema/MyAppDB.pm> |
752 | along with the database connect string. |
753 | |
754 | If you look in the C<lib/MyApp/Schema> directory, you will find that |
755 | C<MyAppDB.pm> is no longer using L<DBIx::Class::Schema::Loader> as its |
756 | base class (L<DBIx::Class::Schema::Loader> is only being used by the |
757 | helper to load the schema once and then create the static files for us) |
758 | and that it only contains a call to the C<load_classes> method. You |
759 | will also find that C<lib/MyApp/Schema> contains a C<MyAppDB> |
760 | subdirectory, with one file inside this directory for each of the tables |
761 | in our simple database (C<Authors.pm>, C<BookAuthors.pm>, and |
762 | C<Books.pm>). These three files were created based on the information |
763 | found by L<DBIx::Class::Schema::Loader> as the helper ran. |
764 | |
765 | The idea with all of the files created under C<lib/MyApp/Schema> by the |
766 | C<create=static> option is to only edit the files below the C<# DO NOT |
767 | MODIFY THIS OR ANYTHING ABOVE!> warning. If you place all of your |
768 | changes below that point in the file, you can regenerate the |
769 | auto-generated information at the top of each file should your database |
770 | structure get updated. |
771 | |
772 | Also note the "flow" of the model information across the various files |
773 | and directories. Catalyst will initially load the model from |
774 | C<lib/MyApp/Model/MyAppDB.pm>. This file contains a reference to |
775 | C<lib/MyApp/Schema/MyAppDB.pm>, so that file is loaded next. Finally, |
776 | the call to C<load_classes> in that file will load each of the |
777 | table-specific "results source" files from the C<lib/MyApp/Schema/MyAppDB> |
778 | subdirectory. These three table-specific DBIC schema files will then be |
779 | used to create three table-specific Catalyst models every time the |
780 | application starts (you can see these three model files listed in |
781 | the debug output generated when you launch the application). |
782 | |
783 | |
784 | =head2 Updating the Generated DBIC Schema Files |
785 | |
786 | |
787 | Let's manually add some relationship information to the auto-generated |
788 | schema files. First edit C<lib/MyApp/Schema/MyAppDB/Books.pm> and |
789 | add the following text below the C<# You can replace this text...> |
790 | comment: |
791 | |
792 | # |
793 | # Set relationships: |
794 | # |
795 | |
796 | # has_many(): |
797 | # args: |
798 | # 1) Name of relationship, DBIC will create accessor with this name |
799 | # 2) Name of the model class referenced by this relationship |
800 | # 3) Column name in *foreign* table |
801 | __PACKAGE__->has_many(book_authors => 'MyApp::Schema::MyAppDB::BookAuthors', 'book_id'); |
802 | |
803 | # many_to_many(): |
804 | # args: |
805 | # 1) Name of relationship, DBIC will create accessor with this name |
806 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
807 | # 3) Name of belongs_to() relationship in model class of has_many() above |
808 | # You must already have the has_many() defined to use a many_to_many(). |
809 | __PACKAGE__->many_to_many(authors => 'book_authors', 'author'); |
810 | |
811 | |
812 | B<Note:> Be careful to put this code I<above> the C<1;> at the end of the |
813 | file. As with any Perl package, we need to end the last line with |
814 | a statement that evaluates to C<true>. This is customarily done with |
815 | C<1;> on a line by itself. |
816 | |
817 | This code defines both a C<has_many> and a C<many_to_many> relationship. |
818 | The C<many_to_many> relationship is optional, but it makes it easier to |
819 | map a book to its collection of authors. Without it, we would have to |
820 | "walk" though the C<book_authors> table as in C<$book-E<gt>book_authors- |
821 | E<gt>first-E<gt>author-E<gt>last_name> (we will see examples on how to |
822 | use DBIC objects in your code soon, but note that because C<$book- |
823 | E<gt>book_authors> can return multiple authors, we have to use C<first> |
824 | to display a single author). C<many_to_many> allows us to use the |
825 | shorter C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. Note that you |
826 | cannot define a C<many_to_many> relationship without also having the |
827 | C<has_many> relationship in place. |
828 | |
829 | Then edit C<lib/MyApp/Schema/MyAppDB/Authors.pm> and add relationship |
830 | information as follows (again, be careful to put in above the C<1;> but |
831 | below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment): |
832 | |
833 | # |
834 | # Set relationships: |
835 | # |
836 | |
837 | # has_many(): |
838 | # args: |
839 | # 1) Name of relationship, DBIC will create accessor with this name |
840 | # 2) Name of the model class referenced by this relationship |
841 | # 3) Column name in *foreign* table |
842 | __PACKAGE__->has_many(book_author => 'MyApp::Schema::MyAppDB::BookAuthors', 'author_id'); |
843 | |
844 | # many_to_many(): |
845 | # args: |
846 | # 1) Name of relationship, DBIC will create accessor with this name |
847 | # 2) Name of has_many() relationship this many_to_many() is shortcut for |
848 | # 3) Name of belongs_to() relationship in model class of has_many() above |
849 | # You must already have the has_many() defined to use a many_to_many(). |
850 | __PACKAGE__->many_to_many(books => 'book_author', 'book'); |
851 | |
852 | Finally, do the same for the "join table," |
853 | C<lib/MyApp/Schema/MyAppDB/BookAuthors.pm>: |
854 | |
855 | # |
856 | # Set relationships: |
857 | # |
858 | |
859 | # belongs_to(): |
860 | # args: |
861 | # 1) Name of relationship, DBIC will create accessor with this name |
862 | # 2) Name of the model class referenced by this relationship |
863 | # 3) Column name in *this* table |
864 | __PACKAGE__->belongs_to(book => 'MyApp::Schema::MyAppDB::Books', 'book_id'); |
865 | |
866 | # belongs_to(): |
867 | # args: |
868 | # 1) Name of relationship, DBIC will create accessor with this name |
869 | # 2) Name of the model class referenced by this relationship |
870 | # 3) Column name in *this* table |
871 | __PACKAGE__->belongs_to(author => 'MyApp::Schema::MyAppDB::Authors', 'author_id'); |
872 | |
873 | |
874 | =head1 RUN THE APPLICATION |
875 | |
876 | Run the Catalyst "demo server" script with the C<DBIC_TRACE> option |
877 | (it might still be enabled from earlier in the tutorial, but here |
878 | is an alternate way to specify the option just in case): |
879 | |
880 | $ DBIC_TRACE=1 script/myapp_server.pl |
881 | |
882 | Make sure that the application loads correctly and that you see the |
883 | three dynamically created model class (one for each of the |
884 | table-specific schema classes we created). |
885 | |
886 | Then hit the URL L<http://localhost:3000/books/list> and be sure that |
887 | the book list is displayed. |
888 | |
889 | |
890 | =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE |
891 | |
892 | In some situations, it can be useful to run your application and |
893 | display a page without using a browser. Catalyst lets you do this |
894 | using the C<scripts/myapp_test.pl> script. Just supply the URL you |
895 | wish to display and it will run that request through the normal |
896 | controller dispatch logic and use the appropriate view to render the |
897 | output (obviously, complex pages may dump a lot of text to your |
898 | terminal window). For example, if you type: |
899 | |
900 | $ script/myapp_test.pl "/books/list" |
901 | |
902 | You should get the same text as if you visited |
903 | L<http://localhost:3000/books/list> with the normal development server |
904 | and asked your browser to view the page source. |
905 | |
906 | |
907 | =head1 UPDATING THE VIEW |
908 | |
909 | Let's add a new column to our book list page that takes advantage of |
910 | the relationship information we manually added to our schema files |
911 | in the previous section. Edit C<root/src/books/list.tt2> add add the |
912 | following code below the existing table cell that contains |
913 | C<book.rating> (IOW, add a new table cell below the existing two |
914 | C<td> cells): |
915 | |
916 | <td> |
917 | [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%] |
918 | [% # loop in 'side effect notation' to load just the last names of the -%] |
919 | [% # authors into the list. Note that the 'push' TT vmethod does not -%] |
920 | [% # a value, so nothing will be printed here. But, if you have something -%] |
921 | [% # in TT that does return a method and you don't want it printed, you -%] |
922 | [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%] |
923 | [% # call it and discard the return value. -%] |
924 | [% tt_authors = [ ]; |
925 | tt_authors.push(author.last_name) FOREACH author = book.authors %] |
926 | [% # Now use a TT 'virtual method' to display the author count in parens -%] |
927 | [% # Note the use of the TT filter "| html" to escape dangerous characters -%] |
928 | ([% tt_authors.size | html %]) |
929 | [% # Use another TT vmethod to join & print the names & comma separators -%] |
930 | [% tt_authors.join(', ') | html %] |
931 | </td> |
932 | |
933 | Then hit C<Ctrl+R> in your browser (not that you don't need to reload |
934 | the development server or use the C<-r> option when updating TT |
935 | templates) and you should now the the number of authors each book and |
936 | a comma-separated list of the author's last names. |
937 | |
938 | If you are still running the development server with C<DBIC_TRACE> |
939 | enabled, you should also now see five more C<SELECT> statements in the |
940 | debug output (one for each book as the authors are being retrieved by |
941 | DBIC). |
942 | |
943 | Also note that we are using "| html", a type of TT filter, to escape |
944 | characters such as E<lt> and E<gt> to < and > and avoid various |
945 | types of dangerous hacks against your application. In a real |
946 | application, you would probably want to put "| html" at the end of |
947 | every field where a user has control over the information that can |
948 | appear in that field (and can therefore inject markup or code if you |
949 | don't "neutralize" those fields). In addition to "| html", Template |
950 | Toolkit has a variety of other useful filters that can found in the |
951 | documentation for L<Template::Filters|Template::Filters>. |
952 | |
953 | |
954 | =head2 Using C<RenderView> for the Default View |
955 | |
956 | B<NOTE: The rest of this part of the tutorial is optional. You can |
957 | skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>, |
958 | if you wish.> |
959 | |
960 | Once your controller logic has processed the request from a user, it |
961 | forwards processing to your view in order to generate the appropriate |
962 | response output. Catalyst uses |
963 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by |
964 | default to automatically performs this operation. If you look in |
965 | C<lib/MyApp/Controller/Root.pm>, you should see the empty |
966 | definition for the C<sub end> method: |
967 | |
968 | sub end : ActionClass('RenderView') {} |
969 | |
970 | The following bullet points provide a quick overview of the |
971 | C<RenderView> process: |
972 | |
973 | =over 4 |
974 | |
975 | =item * |
976 | |
977 | C<Root.pm> is designed to hold application-wide logic. |
978 | |
979 | =item * |
980 | |
981 | At the end of a given user request, Catalyst will call the most specific |
982 | C<end> method that's appropriate. For example, if the controller for a |
983 | request has an C<end> method defined, it will be called. However, if |
984 | the controller does not define a controller-specific C<end> method, the |
985 | "global" C<end> method in C<Root.pm> will be called. |
986 | |
987 | =item * |
988 | |
989 | Because the definition includes an C<ActionClass> attribute, the |
990 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic |
991 | will be executed B<after> any code inside the definition of C<sub end> |
992 | is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions> |
993 | for more information on C<ActionClass>. |
994 | |
995 | =item * |
996 | |
997 | Because C<sub end> is empty, this effectively just runs the default |
998 | logic in C<RenderView>. However, you can easily extend the |
999 | C<RenderView> logic by adding your own code inside the empty method body |
1000 | (C<{}>) created by the Catalyst Helpers when we first ran the |
1001 | C<catalyst.pl> to initialize our application. See |
1002 | L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more |
1003 | detailed information on how to extended C<RenderView> in C<sub end>. |
1004 | |
1005 | =back |
1006 | |
1007 | |
1008 | =head2 Using The Default Template Name |
1009 | |
1010 | By default, C<Catalyst::View::TT> will look for a template that uses the |
1011 | same name as your controller action, allowing you to save the step of |
1012 | manually specifying the template name in each action. For example, this |
1013 | would allow us to remove the |
1014 | C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our |
1015 | C<list> action in the Books controller. Open |
1016 | C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line |
1017 | to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line |
1018 | has changed): |
1019 | |
1020 | =head2 list |
1021 | |
1022 | Fetch all book objects and pass to books/list.tt2 in stash to be displayed |
1023 | |
1024 | =cut |
1025 | |
1026 | sub list : Local { |
1027 | # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst |
1028 | # 'Context' that's used to 'glue together' the various components |
1029 | # that make up the application |
1030 | my ($self, $c) = @_; |
1031 | |
1032 | # Retrieve all of the book records as book model objects and store in the |
1033 | # stash where they can be accessed by the TT template |
1034 | $c->stash->{books} = [$c->model('MyAppDB::Books')->all]; |
1035 | |
1036 | # Set the TT template to use. You will almost always want to do this |
1037 | # in your action methods (actions methods respond to user input in |
1038 | # your controllers). |
1039 | #$c->stash->{template} = 'books/list.tt2'; |
1040 | } |
1041 | |
1042 | C<Catalyst::View::TT> defaults to looking for a template with no |
1043 | extension. In our case, we need to override this to look for an |
1044 | extension of C<.tt2>. Open C<lib/MyApp/View/TT.pm> and add the |
1045 | C<TEMPLATE_EXTENSION> definition as follows: |
1046 | |
1047 | __PACKAGE__->config({ |
1048 | CATALYST_VAR => 'Catalyst', |
1049 | INCLUDE_PATH => [ |
1050 | MyApp->path_to( 'root', 'src' ), |
1051 | MyApp->path_to( 'root', 'lib' ) |
1052 | ], |
1053 | PRE_PROCESS => 'config/main', |
1054 | WRAPPER => 'site/wrapper', |
1055 | ERROR => 'error.tt2', |
1056 | TIMER => 0, |
1057 | TEMPLATE_EXTENSION => '.tt2', |
1058 | }); |
1059 | |
1060 | You should now be able to restart the development server as per the |
1061 | previous section and access the L<http://localhost:3000/books/list> |
1062 | as before. |
1063 | |
1064 | B<NOTE:> Please note that if you use the default template technique, |
1065 | you will B<not> be able to use either the C<$c-E<gt>forward> or |
1066 | the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and |
1067 | Part 9 of the Tutorial). |
1068 | |
1069 | |
1070 | =head2 Return To A Manually-Specified Template |
1071 | |
1072 | In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach> |
1073 | later in the tutorial, you should remove the comment from the |
1074 | statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>: |
1075 | |
1076 | $c->stash->{template} = 'books/list.tt2'; |
1077 | |
1078 | Then delete the C<TEMPLATE_EXTENSION> line in |
1079 | C<lib/MyApp/View/TT.pm>. |
1080 | |
1081 | You should then be able to restart the development server and |
1082 | access L<http://localhost:3000/books/list> in the same manner as |
1083 | with earlier sections. |
1084 | |
1085 | |
1086 | =head1 AUTHOR |
1087 | |
1088 | Kennedy Clark, C<hkclark@gmail.com> |
1089 | |
1090 | Please report any errors, issues or suggestions to the author. The |
1091 | most recent version of the Catalyst Tutorial can be found at |
1092 | L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>. |
1093 | |
1094 | Copyright 2006, Kennedy Clark, under Creative Commons License |
1095 | (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>). |
1096 | |