3 Catalyst::Manual::Tutorial::MoreCatalystBasics - Catalyst Tutorial - Part 3: More Catalyst Application Development Basics
8 This is B<Part 3 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
24 B<More Catalyst Basics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::Authentication>
36 L<Authorization|Catalyst::Manual::Tutorial::Authorization>
40 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::Appendices>
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
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|Catalyst::Manual::Tutorial::Intro>.
72 =head1 CREATE A NEW APPLICATION
74 The remainder of the tutorial will build an application called C<MyApp>.
75 First use the Catalyst C<catalyst.pl> script to initialize the framework
76 for the C<MyApp> application (make sure you aren't still inside the
77 directory of the C<Hello> application from the previous part of the
82 created "MyApp/script"
86 created "MyApp/script/myapp_create.pl"
89 This creates a similar skeletal structure to what we saw in Part 2 of
90 the tutorial, except with C<MyApp> and C<myapp> substituted for
91 C<Hello> and C<hello>.
94 =head1 EDIT THE LIST OF CATALYST PLUGINS
96 One of the greatest benefits of Catalyst is that it has such a large
97 library of plugins and base classes available. Plugins are used to
98 seamlessly integrate existing Perl modules into the overall Catalyst
99 framework. In general, they do this by adding additional methods to the
100 C<context> object (generally written as C<$c>) that Catalyst passes to
101 every component throughout the framework.
103 By default, Catalyst enables three plugins/flags:
111 Enables the Catalyst debug output you saw when we started the
112 C<script/myapp_server.pl> development server earlier. You can remove
113 this item when you place your application into production.
115 As you may have noticed, C<-Debug> is not a plugin, but a I<flag>.
116 Although most of the items specified on the C<__PACKAGE__-E<gt>setup>
117 line of your application class will be plugins, Catalyst supports a
118 limited number of flag options (of these, C<-Debug> is the most
119 common). See the documentation for C<Catalyst.pm> to get details on
120 other flags (currently C<-Engine>, C<-Home>, and C<-Log>).
122 If you prefer, you can use the C<$c-E<gt>debug> method to enable debug
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.
133 L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader>
135 C<ConfigLoader> provides an automatic way to load configurable
136 parameters for your application from a central
137 L<Config::General|Config::General> file (versus having the values
138 hard-coded inside your Perl modules). Config::General uses syntax
139 very similar to Apache configuration files. We will see how to use
140 this feature of Catalyst during the authentication and authorization
141 sections (Part 5 and Part 6).
143 B<IMPORTANT NOTE:> If you are using a version of
144 L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, you need to
145 be aware that Catalyst changed from a default format of YAML to the
146 more straightforward C<Config::General> format. This tutorial use the
147 newer C<myapp.conf> configuration file for C<Config::General> instead
148 of C<myapp.yml> for YAML. However, Catalyst has long supported both
149 formats and Catalyst will automatically use either C<myapp.conf> or
150 C<myapp.yml> (or any other format supported by
151 L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and
152 L<Config::Any|Config::Any>). If you are using a versions of
153 Catalyst::Devel prior to 1.06, you can convert to the newer format by
154 simply creating the C<myapp.yml> file manually and deleting
155 C<myapp.yml>. The default contents of C<myapp.conf> should only
156 consist of one line: C<name MyApp>.
158 B<TIP>: This script can be useful for converting between configuration
161 perl -Ilib -e 'use MyApp; use Config::General;
162 Config::General->new->save_file("myapp.conf", MyApp->config);'
164 B<NOTE:> The default C<myapp.conf> should look like:
170 L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple>
172 C<Static::Simple> provides an easy method of serving static content such
173 as images and CSS files under the development server.
177 For our application, we want to add one new plugin into the mix. To
178 do this, edit C<lib/MyApp.pm> (this file is generally referred to as
179 your I<application class>) and delete the line with:
181 __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/);
183 Then replace it with:
185 __PACKAGE__->setup(qw/
193 B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of
194 techniques to load these plugins/flags. If you are following along in
195 Ubuntu 8.10, you should have C<Catalyst::Devel> v1.07 and see the
196 default code shown above. If you are using v1.08, you should see the
197 following by default:
199 use Catalyst qw/-Debug
203 __PACKAGE__->setup();
205 Don't let these variations confuse you -- they all accomplish the same
208 This tells Catalyst to start using one new plugin,
209 L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a
210 stack trace to the standard Catalyst "debug screen" (the screen
211 Catalyst sends to your browser when an error occurs). Be aware that
212 L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
213 browser, not in the console window from which you're running your
214 application, which is where logging output usually goes.
222 C<__PACKAGE__> is just a shorthand way of referencing the name of the
223 package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__>
224 is equivalent to C<MyApp>.
228 You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace>
229 before you put your application into production, but it can be helpful
234 When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can
235 omit C<Catalyst::Plugin::> from the name. Additionally, you can
236 spread the plugin names across multiple lines as shown here, or place
237 them all on one (or more) lines as with the default configuration.
242 =head1 CREATE A CATALYST CONTROLLER
244 As discussed earlier, controllers are where you write methods that
245 interact with user input. Typically, controller methods respond to
246 C<GET> and C<POST> messages from the user's web browser.
248 Use the Catalyst C<create> script to add a controller for book-related
251 $ script/myapp_create.pl controller Books
252 exists "/home/me/MyApp/script/../lib/MyApp/Controller"
253 exists "/home/me/MyApp/script/../t"
254 created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm"
255 created "/home/me/MyApp/script/../t/controller_Books.t"
257 Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Part 2 of
258 the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for
259 each of the three parts of MVC: C<Model>, C<View>, and C<Controller>)
260 and add the following method to the controller:
264 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
269 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
270 # 'Context' that's used to 'glue together' the various components
271 # that make up the application
274 # Retrieve all of the book records as book model objects and store in the
275 # stash where they can be accessed by the TT template
276 # $c->stash->{books} = [$c->model('DB::Books')->all];
277 # But, for now, use this code until we create the model later
278 $c->stash->{books} = '';
280 # Set the TT template to use. You will almost always want to do this
281 # in your action methods (action methods respond to user input in
283 $c->stash->{template} = 'books/list.tt2';
286 B<TIP>: See Appendix 1 for tips on removing the leading spaces when
287 cutting and pasting example code from POD-based documents.
289 Programmers experienced with object-oriented Perl should recognize
290 C<$self> as a reference to the object where this method was called.
291 On the other hand, C<$c> will be new to many Perl programmers who have
292 not used Catalyst before (it's sometimes written as C<$context>). The
293 Context object is automatically passed to all Catalyst components. It
294 is used to pass information between components and provide access to
295 Catalyst and plugin functionality.
297 B<Note:> Catalyst actions are regular Perl methods, but they make use
298 of Nicholas Clark's C<attributes> module (that's the "C<: Local>" next
299 to the C<sub list> in the code above) to provide additional
300 information to the Catalyst dispatcher logic. Many newer Catalyst
301 applications are switching to the use of "Literal" C<:Path> actions
302 and C<Args> attribute in lieu of C<: Local> and C<: Private>. For
303 example, C<sub any_method :Path :Args(0)> can be used instead of C<sub
304 index :Private> (because no path was supplied to C<Path> it matches
305 the "empty" URL in the namespace of that module... the same thing
306 C<sub index> would do) or C<sub list :Path('list') :Args(0)> could be
307 used instead of the C<sub list : Local> above (the C<list> argument to
308 C<Path> would make it match on the URL C<list> under C<books>, the
309 namespace of the current module). See "Action Types" in
310 L<Catalyst::Manual::Intro|Catalyst::Manual::Intro> as well as Part 5
311 of this tutorial (Authentication) for additional information. Another
312 popular but more advanced feature is C<Chained> actions that allow a
313 single URL to "chain together" multiple action method calls, each with
314 an appropriate number of arguments (see
315 L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> for
319 =head1 CATALYST VIEWS
321 As mentioned in Part 2 of the tutorial, views are where you render
322 output, typically for display in the user's web browser (but also
323 possibly using other display output-generation systems). The code in
324 C<lib/MyApp/View> selects the I<type> of view to use, with the actual
325 rendering template found in the C<root> directory. As with virtually
326 every aspect of Catalyst, options abound when it comes to the specific
327 view technology you adopt inside your application. However, most
328 Catalyst applications use the Template Toolkit, known as TT (for more
329 information on TT, see L<http://www.template-toolkit.org>). Other
330 somewhat popular view technologies include Mason
331 (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and
332 L<HTML::Template> (L<http://html-template.sourceforge.net>).
335 =head2 Create a Catalyst View
337 When using TT for the Catalyst view, there are two main helper scripts:
343 L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>
347 L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>
351 Both are similar, but C<TT> merely creates the C<lib/MyApp/View/TT.pm>
352 file and leaves the creation of any hierarchical template organization
353 entirely up to you. (It also creates a C<t/view_TT.t> file for testing;
354 test cases will be discussed in Part 8.) On the other hand, the
355 C<TTSite> helper creates a modular and hierarchical view layout with
356 separate Template Toolkit (TT) files for common header and footer
357 information, configuration values, a CSS stylesheet, and more.
359 While TTSite is useful to bootstrap a project, most in the Catalyst
360 community recommend that it's easier to learn both Catalyst and
361 Template Toolkit if you use the more basic TT approach. Consequently,
362 this tutorial will use "plain old TT."
364 Enter the following command to enable the C<TT> style of view
365 rendering for this tutorial:
367 $ script/myapp_create.pl view TT TT
368 exists "/home/me/MyApp/script/../lib/MyApp/View"
369 exists "/home/me/MyApp/script/../t"
370 created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm"
371 created "/home/me/MyApp/script/../t/view_TT.t"
373 This simply creates a view called C<TT> (the second 'TT' argument) in
374 a file called C<TT.pm> (the first 'TT' argument). It is now up to you
375 to decide how you want to structure your view layout. For the
376 tutorial, we will start with a very simple TT template to initially
377 demonstrate the concepts, but quickly migrate to a more typical
378 "wrapper page" type of configuration (where the "wrapper" controls the
379 overall "look and feel" of your site from a single file or set of
382 Edit C<lib/MyApp/View/TT.pm> and you should see that the default
383 contents contains something similar to the following:
385 __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt');
387 And update it to match:
390 # Change default TT extension
391 TEMPLATE_EXTENSION => '.tt2',
392 # Set the location for TT files
394 MyApp->path_to( 'root', 'src' ),
398 B<NOTE:> Make sure to add a comma after '.tt2' outside the single
401 This changes the default extension for Template Toolkit from '.tt' to
402 '.tt2' and changes the base directory for your template files from
403 C<root> to C<root/src>.
406 =head2 Create a TT Template Page
408 First create a directory for book-related TT templates:
410 $ mkdir -p root/src/books
412 Then create C<root/src/books/list.tt2> in your editor and enter:
414 [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%]
415 [% # see this "chomping" in your browser because HTML ignores blank lines, but -%]
416 [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
417 [%- # optional, but both the beginning and the ending TT tags support chomping. -%]
419 [% # Provide a title -%]
420 [% META title = 'Book List' -%]
423 <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr>
424 [% # Display each book in a table row %]
425 [% FOREACH book IN books -%]
427 <td>[% book.title %]</td>
428 <td>[% book.rating %]</td>
433 As indicated by the inline comments above, the C<META title> line uses
434 TT's META feature to provide a title to the "wrapper" that we will
435 create later. Meanwhile, the C<FOREACH> loop iterates through each
436 C<book> model object and prints the C<title> and C<rating> fields.
438 If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT
439 code. TT supports a wide variety of directives for "calling" other
440 files, looping, conditional logic, etc. In general, TT simplifies the
441 usual range of Perl operators down to the single dot (C<.>) operator.
442 This applies to operations as diverse as method calls, hash lookups, and
443 list index values (see
444 L<http://search.cpan.org/perldoc?Template::Manual::Variables>
445 for details and examples). In addition to the usual C<Template> module
446 Pod documentation, you can access the TT manual at
447 L<http://search.cpan.org/perldoc?Template::Manual>.
449 B<TIP:> While you can build all sorts of complex logic into your TT
450 templates, you should in general keep the "code" part of your templates
451 as simple as possible. If you need more complex logic, create helper
452 methods in your model that abstract out a set of code into a single call
453 from your TT template. (Note that the same is true of your controller
454 logic as well -- complex sections of code in your controllers should
455 often be pulled out and placed into your model objects.)
458 =head2 Test Run The Application
460 To test your work so far, first start the development server:
462 $ script/myapp_server.pl
464 Then point your browser to L<http://localhost:3000> and you should
465 still get the Catalyst welcome page. Next, change the URL in your
466 browser to L<http://localhost:3000/books/list>. If you have
467 everything working so far, you should see a web page that displays
468 nothing other than our column headers for "Title", "Rating", and
469 "Author(s)" -- we will not see any books until we get the database and
472 If you run into problems getting your application to run correctly, it
473 might be helpful to refer to some of the debugging techniques covered in
474 the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the
478 =head1 CREATE A SQLITE DATABASE
480 In this step, we make a text file with the required SQL commands to
481 create a database table and load some sample data. We will use SQLite,
482 a popular database that is lightweight and easy to use. Open
483 C<myapp01.sql> in your editor and enter:
486 -- Create a very simple database to hold book and author information
489 id INTEGER PRIMARY KEY,
493 -- 'book_authors' is a many-to-many join table between books & authors
494 CREATE TABLE book_authors (
497 PRIMARY KEY (book_id, author_id)
499 CREATE TABLE authors (
500 id INTEGER PRIMARY KEY,
505 --- Load some sample data
507 INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5);
508 INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5);
509 INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4);
510 INSERT INTO books VALUES (4, 'Perl Cookbook', 5);
511 INSERT INTO books VALUES (5, 'Designing with Web Standards', 5);
512 INSERT INTO authors VALUES (1, 'Greg', 'Bastien');
513 INSERT INTO authors VALUES (2, 'Sara', 'Nasseh');
514 INSERT INTO authors VALUES (3, 'Christian', 'Degu');
515 INSERT INTO authors VALUES (4, 'Richard', 'Stevens');
516 INSERT INTO authors VALUES (5, 'Douglas', 'Comer');
517 INSERT INTO authors VALUES (6, 'Tom', 'Christiansen');
518 INSERT INTO authors VALUES (7, 'Nathan', 'Torkington');
519 INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman');
520 INSERT INTO book_authors VALUES (1, 1);
521 INSERT INTO book_authors VALUES (1, 2);
522 INSERT INTO book_authors VALUES (1, 3);
523 INSERT INTO book_authors VALUES (2, 4);
524 INSERT INTO book_authors VALUES (3, 5);
525 INSERT INTO book_authors VALUES (4, 6);
526 INSERT INTO book_authors VALUES (4, 7);
527 INSERT INTO book_authors VALUES (5, 8);
529 Then use the following command to build a C<myapp.db> SQLite database:
531 $ sqlite3 myapp.db < myapp01.sql
533 If you need to create the database more than once, you probably want to
534 issue the C<rm myapp.db> command to delete the database before you use
535 the C<sqlite3 myapp.db E<lt> myapp01.sql> command.
537 Once the C<myapp.db> database file has been created and initialized, you
538 can use the SQLite command line environment to do a quick dump of the
543 Enter ".help" for instructions
544 sqlite> select * from books;
545 1|CCSP SNRS Exam Certification Guide|5
546 2|TCP/IP Illustrated, Volume 1|5
547 3|Internetworking with TCP/IP Vol.1|4
549 5|Designing with Web Standards|5
555 $ sqlite3 myapp.db "select * from books"
556 1|CCSP SNRS Exam Certification Guide|5
557 2|TCP/IP Illustrated, Volume 1|5
558 3|Internetworking with TCP/IP Vol.1|4
560 5|Designing with Web Standards|5
562 As with most other SQL tools, if you are using the full "interactive"
563 environment you need to terminate your SQL commands with a ";" (it's not
564 required if you do a single SQL statement on the command line). Use
565 ".q" to exit from SQLite from the SQLite interactive mode and return to
566 your OS command prompt.
569 =head1 DATABASE ACCESS WITH C<DBIx::Class>
571 Catalyst can be used with virtually any form of persistent datastore
572 available via Perl. For example,
573 L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to easily
574 access databases through the traditional Perl C<DBI> interface. However,
575 most Catalyst applications use some form of ORM technology to
576 automatically create and save model objects as they are used. Although
577 L<Class::DBI|Class::DBI> has been a popular choice in the past, Matt
578 Trout's L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly
579 emerged as the Perl-based ORM technology of choice. Most new Catalyst
580 applications rely on DBIC, as will this tutorial.
583 =head2 Create a Dynamic DBIC Model
585 Use the C<create=dynamic> model helper option to build a model that
586 dynamically reads your database structure every time the application
589 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=dynamic dbi:SQLite:myapp.db
590 exists "/home/me/MyApp/script/../lib/MyApp/Model"
591 exists "/home/me/MyApp/script/../t"
592 exists "/home/me/MyApp/script/../lib/MyApp"
593 created "/home/me/MyApp/script/../lib/MyApp/Schema.pm"
594 created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
595 created "/home/me/MyApp/script/../t/model_DB.t"
598 C<DB> is the name of the model class to be created by the helper in
599 C<lib/MyApp/Model>. C<DBIC::Schema> is the type of the model to
600 create. C<MyApp::Schema> is the name of the DBIC schema file written
601 to C<lib/MyApp/Schema.pm>. Because we specified C<create=dynamic> to
603 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to
604 dynamically load the schema information from the database every time
605 the application starts. DBIC uses the schema to load other classes
606 that represent the tables in your database (DBIC refers to these
607 "table objects" as "result sources," see
608 L<DBIx::Class::ResultSource|DBIx::Class::ResultSource>). And finally,
609 C<dbi:SQLite:myapp.db> is the standard DBI connect string for use with
612 B<NOTE:> Although the C<create=dynamic> option to the DBIC helper
613 makes for a nifty demonstration, is only really suitable for very
614 small applications. After this demonstration, you should almost always
615 use the C<create=static> option that we switch to below.
618 =head1 ENABLE THE MODEL IN THE CONTROLLER
620 Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we
621 left disabled earlier (un-comment the line containing
622 C<[$c-E<gt>model('DB::Books')-E<gt>all]> and delete the next 2 lines):
626 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
631 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
632 # 'Context' that's used to 'glue together' the various components
633 # that make up the application
636 # Retrieve all of the book records as book model objects and store in the
637 # stash where they can be accessed by the TT template
638 $c->stash->{books} = [$c->model('DB::Books')->all];
640 # Set the TT template to use. You will almost always want to do this
641 # in your action methods (action methods respond to user input in
643 $c->stash->{template} = 'books/list.tt2';
646 B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented
647 above written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The
648 two are equivalent. Either way, C<$c-E<gt>model> returns a
649 L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries
650 against the database and iterating over the set of results that are
653 We are using the C<-E<gt>all> to fetch all of the books. DBIC
654 supports a wide variety of more advanced operations to easily do
655 things like filtering and sorting the results. For example, the
656 following could be used to sort the results by descending title:
658 $c->model('DB::Books')->search({}, {order_by => 'title DESC'});
660 Some other examples are provided in
661 L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with
662 additional information found at L<DBIx::Class::ResultSet/search>,
663 L<DBIx::Class::Manual::FAQ/Searching>,
664 L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro>
665 and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>.
668 =head2 Test Run The Application
670 First, let's enable an environment variable option that causes
671 DBIx::Class to dump the SQL statements it's using to access the database
672 (this option can provide extremely helpful troubleshooting information):
674 $ export DBIC_TRACE=1
676 This assumes you are using BASH as your shell -- adjust accordingly if
677 you are using a different shell (for example, under tcsh, use
678 C<setenv DBIC_TRACE 1>).
680 B<NOTE:> You can also set this in your code using
681 C<$class-E<gt>storage-E<gt>debug(1);>. See
682 L<DBIx::Class::Manual::Troubleshooting> for details (including options
683 to log to file instead of displaying to the Catalyst development server
686 Then launch the Catalyst development server. The log output should
687 display something like:
689 $script/myapp_server.pl
690 [debug] Debug messages enabled
691 [debug] Statistics enabled
692 [debug] Loaded plugins:
693 .----------------------------------------------------------------------------.
694 | Catalyst::Plugin::ConfigLoader 0.20 |
695 | Catalyst::Plugin::StackTrace 0.08 |
696 | Catalyst::Plugin::Static::Simple 0.20 |
697 '----------------------------------------------------------------------------'
699 [debug] Loaded dispatcher "Catalyst::Dispatcher"
700 [debug] Loaded engine "Catalyst::Engine::HTTP"
701 [debug] Found home "/home/me/MyApp"
702 [debug] Loaded Config "/home/me/MyApp/myapp.conf"
703 [debug] Loaded components:
704 .-----------------------------------------------------------------+----------.
706 +-----------------------------------------------------------------+----------+
707 | MyApp::Controller::Books | instance |
708 | MyApp::Controller::Root | instance |
709 | MyApp::Model::DB | instance |
710 | MyApp::Model::DB::Authors | class |
711 | MyApp::Model::DB::BookAuthors | class |
712 | MyApp::Model::DB::Books | class |
713 | MyApp::View::TT | instance |
714 '-----------------------------------------------------------------+----------'
716 [debug] Loaded Private actions:
717 .----------------------+--------------------------------------+--------------.
718 | Private | Class | Method |
719 +----------------------+--------------------------------------+--------------+
720 | /default | MyApp::Controller::Root | default |
721 | /end | MyApp::Controller::Root | end |
722 | /index | MyApp::Controller::Root | index |
723 | /books/index | MyApp::Controller::Books | index |
724 | /books/list | MyApp::Controller::Books | list |
725 '----------------------+--------------------------------------+--------------'
727 [debug] Loaded Path actions:
728 .-------------------------------------+--------------------------------------.
730 +-------------------------------------+--------------------------------------+
733 | /books | /books/index |
734 | /books/list | /books/list |
735 '-------------------------------------+--------------------------------------'
737 [info] MyApp powered by Catalyst 5.7014
738 You can connect to your server at http://localhost:3000
740 B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from
741 the 'base' directory of your application, not inside the C<script>
742 directory itself or it will not be able to locate the C<myapp.db>
743 database file. You can use a fully qualified or a relative path to
744 locate the database file, but we did not specify that when we ran the
745 model helper earlier.
747 Some things you should note in the output above:
753 Catalyst::Model::DBIC::Schema dynamically created three model classes,
754 one to represent each of the three tables in our database
755 (C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>,
756 and C<MyApp::Model::DB::Books>).
760 The "list" action in our Books controller showed up with a path of
765 Point your browser to L<http://localhost:3000> and you should still get
766 the Catalyst welcome page.
768 Next, to view the book list, change the URL in your browser to
769 L<http://localhost:3000/books/list>. You should get a list of the five
770 books loaded by the C<myapp01.sql> script above without any formatting.
771 The rating for each book should appear on each row, but the "Author(s)"
772 column will still be blank (we will fill that in later).
774 Also notice in the output of the C<script/myapp_server.pl> that DBIC
775 used the following SQL to retrieve the data:
777 SELECT me.id, me.title, me.rating FROM books me
779 because we enabled DBIC_TRACE.
781 You now have the beginnings of a simple but workable web application.
782 Continue on to future sections and we will develop the application
786 =head1 CREATE A WRAPPER FOR THE VIEW
788 When using TT, you can (and should!) create a wrapper that will
789 literally wrap content around each of your templates. This is
790 certainly useful as you have one main source for changing things that
791 will appear across your entire site/application instead of having to
792 edit many individual files.
795 =head2 Configure TT.pm For The Wrapper
797 In order to create a wrapper, you must first edit your TT view and
798 tell it where to find your wrapper file. Your TT view is located in
799 C<lib/MyApp/View/TT.pm>.
801 Edit C<lib/MyApp/View/TT.pm> and change it to match the following:
804 # Change default TT extension
805 TEMPLATE_EXTENSION => '.tt2',
806 # Set the location for TT files
808 MyApp->path_to( 'root', 'src' ),
810 # Set to 1 for detailed timer stats in your HTML as comments
812 # This is your wrapper template located in the 'root/src'
813 WRAPPER => 'wrapper.tt2',
817 =head2 Create the Wrapper Template File and Stylesheet
819 Next you need to set up your wrapper template. Basically, you'll want
820 to take the overall layout of your site and put it into this file.
821 For the tutorial, open C<root/src/wrapper.tt2> and input the following:
823 <?xml version="1.0" encoding="UTF-8"?>
824 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
825 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
827 <title>[% template.title or "My Catalyst App!" %]</title>
828 <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" />
834 [%# Your logo could go here -%]
835 <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" />
836 [%# Insert the page title -%]
837 <h1>[% template.title or site.title %]</h1>
844 <li><a href="[% c.uri_for('/books/list') %]">Home</a></li>
845 <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li>
846 <li><a href="mailto:nobody@nowhere.com" title="Contact Us">Contact Us</a></li>
848 </div><!-- end menu -->
851 [%# Status and error messages %]
852 <span class="message">[% status_msg %]</span>
853 <span class="error">[% error_msg %]</span>
854 [%# This is where TT will stick all of your template's contents. -%]
856 </div><!-- end content -->
857 </div><!-- end bodyblock -->
859 <div id="footer">Copyright (c) your name goes here</div>
860 </div><!-- end outer -->
865 Notice the status and error message sections in the code above:
867 <span class="status">[% status_msg %]</span>
868 <span class="error">[% error_msg %]</span>
870 If we set either message in the Catalyst stash (e.g.,
871 C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it
872 will be displayed whenever any view used by that request is rendered.
873 The C<message> and C<error> CSS styles can be customized to suit your
874 needs in the C<root/static/css/main.css> file we create below.
882 The Catalyst stash only lasts for a single HTTP request. If
883 you need to retain information across requests you can use
884 L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
885 Catalyst sessions in the Authentication part of the tutorial).
889 Although it is beyond the scope of this tutorial, you may wish to use
890 a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or
891 Dojo (L<http://www.dojotoolkit.org>).
896 =head3 Create A Basic Stylesheet
898 First create a central location for stylesheets under the static
901 $ mkdir root/static/css
903 Then open the file C<root/static/css/main.css> (the file referenced in
904 the stylesheet href link of our wrapper above) and add the following
923 background-color: #ddd;
929 padding: 0 0 50% 5px;
931 background-color: #ddd;
944 You may wish to check out a "CSS Framework" like Emastic
945 (L<http://code.google.com/p/emastic/>) as a way to quickly
946 provide lots of high-quality CSS functionality.
949 =head2 Test Run The Application
951 Restart the development server and hit "Reload" in your web browser
952 and you should now see a formatted version of our basic book list.
953 Although our wrapper and stylesheet are obviously very simple, you
954 should see how it allows us to control the overall look of an entire
955 website from two central files. To add new pages to the site, just
956 provide a template that fills in the C<content> section of our wrapper
957 template -- the wrapper will provide the overall feel of the page.
960 =head1 A STATIC DATABASE MODEL WITH C<DBIx::Class>
962 =head2 Create Static DBIC Schema Files
964 Unlike the previous DBIC section where we had C<create=dynamic>
965 automatically discover the structure of the database every time the
966 application started, here we will use static schema files for more
967 control. This is typical of most "real world" applications.
969 One option would be to manually create a separate schema file for each
970 table in the database, however, lets use the same
971 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> used
972 earlier with C<create=dynamic> to build the static files for us.
973 First, lets remove the schema file created earlier:
975 $ rm lib/MyApp/Schema.pm
977 Now regenerate the schema using the C<create=static> option:
979 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=static dbi:SQLite:myapp.db
980 exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model"
981 exists "/home/kclark/dev/MyApp/script/../t"
982 Dumping manual schema for MyApp::Schema to directory /home/kclark/dev/MyApp/script/../lib ...
983 Schema dump completed.
984 exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model/DB.pm"
986 We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would
987 have regenerated the same file (note the C<exists> in the output above).
988 If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains
989 a reference to the actual schema file in C<lib/MyApp/Schema.pm>
990 along with the database connect string.
992 If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
994 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base
995 class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is
996 only being used by the helper to load the schema once and then create
997 the static files for us) and C<Schema.pm> only contains a call to the
998 C<load_classes> method. You will also find that C<lib/MyApp>
999 contains a C<Schema> subdirectory, with one file inside this directory
1000 for each of the tables in our simple database (C<Authors.pm>,
1001 C<BookAuthors.pm>, and C<Books.pm>). These three files were created
1002 based on the information found by
1003 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as the
1006 The idea with all of the files created under C<lib/MyApp/Schema> by
1007 the C<create=static> option is to only edit the files below the C<# DO
1008 NOT MODIFY THIS OR ANYTHING ABOVE!> warning. If you place all of your
1009 changes below that point in the file, you can regenerate the
1010 automatically created information at the top of each file should your
1011 database structure get updated.
1013 Also note the "flow" of the model information across the various files
1014 and directories. Catalyst will initially load the model from
1015 C<lib/MyApp/Model/DB.pm>. This file contains a reference to
1016 C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally,
1017 the call to C<load_classes> in C<Schema.pm> will load each of the
1018 table-specific "results source" files from the C<lib/MyApp/Schema>
1019 subdirectory. These three table-specific DBIC schema files will then be
1020 used to create three table-specific Catalyst models every time the
1021 application starts (you can see these three model files listed in
1022 the debug output generated when you launch the application).
1025 =head2 Updating the Generated DBIC Schema Files
1027 Let's manually add some relationship information to the auto-generated
1028 schema files. First edit C<lib/MyApp/Schema/Books.pm> and
1029 add the following text below the C<# You can replace this text...>
1033 # Set relationships:
1038 # 1) Name of relationship, DBIC will create accessor with this name
1039 # 2) Name of the model class referenced by this relationship
1040 # 3) Column name in *foreign* table
1041 __PACKAGE__->has_many(book_authors => 'MyApp::Schema::BookAuthors', 'book_id');
1045 # 1) Name of relationship, DBIC will create accessor with this name
1046 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1047 # 3) Name of belongs_to() relationship in model class of has_many() above
1048 # You must already have the has_many() defined to use a many_to_many().
1049 __PACKAGE__->many_to_many(authors => 'book_authors', 'author');
1052 B<Note:> Be careful to put this code I<above> the C<1;> at the end of the
1053 file. As with any Perl package, we need to end the last line with
1054 a statement that evaluates to C<true>. This is customarily done with
1055 C<1;> on a line by itself.
1057 This code defines both a C<has_many> and a C<many_to_many> relationship.
1058 The C<many_to_many> relationship is optional, but it makes it easier to
1059 map a book to its collection of authors. Without it, we would have to
1060 "walk" though the C<book_authors> table as in
1061 C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name>
1062 (we will see examples on how to use DBIC objects in your code soon,
1063 but note that because C<$book-E<gt>book_authors> can return multiple
1064 authors, we have to use C<first> to display a single author).
1065 C<many_to_many> allows us to use the shorter
1066 C<$book-E<gt>authors-E<gt>first-E<gt>last_name>.
1067 Note that you cannot define a C<many_to_many> relationship without
1068 also having the C<has_many> relationship in place.
1070 Then edit C<lib/MyApp/Schema/Authors.pm> and add relationship
1071 information as follows (again, be careful to put in above the C<1;> but
1072 below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment):
1075 # Set relationships:
1080 # 1) Name of relationship, DBIC will create accessor with this name
1081 # 2) Name of the model class referenced by this relationship
1082 # 3) Column name in *foreign* table
1083 __PACKAGE__->has_many(book_author => 'MyApp::Schema::BookAuthors', 'author_id');
1087 # 1) Name of relationship, DBIC will create accessor with this name
1088 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1089 # 3) Name of belongs_to() relationship in model class of has_many() above
1090 # You must already have the has_many() defined to use a many_to_many().
1091 __PACKAGE__->many_to_many(books => 'book_author', 'book');
1093 Finally, do the same for the "join table,"
1094 C<lib/MyApp/Schema/BookAuthors.pm>:
1097 # Set relationships:
1102 # 1) Name of relationship, DBIC will create accessor with this name
1103 # 2) Name of the model class referenced by this relationship
1104 # 3) Column name in *this* table
1105 __PACKAGE__->belongs_to(book => 'MyApp::Schema::Books', 'book_id');
1109 # 1) Name of relationship, DBIC will create accessor with this name
1110 # 2) Name of the model class referenced by this relationship
1111 # 3) Column name in *this* table
1112 __PACKAGE__->belongs_to(author => 'MyApp::Schema::Authors', 'author_id');
1115 =head2 Run The Application
1117 Run the Catalyst "demo server" script with the C<DBIC_TRACE> option
1118 (it might still be enabled from earlier in the tutorial, but here
1119 is an alternate way to specify the option just in case):
1121 $ DBIC_TRACE=1 script/myapp_server.pl
1123 Make sure that the application loads correctly and that you see the
1124 three dynamically created model class (one for each of the
1125 table-specific schema classes we created).
1127 Then hit the URL L<http://localhost:3000/books/list> and be sure that
1128 the book list is displayed via the relationships established above. You
1129 can leave the development server running for the next step if you wish.
1131 B<Note:> You will not see the authors yet because the view does not yet
1132 use the new relations. Read on to the next section where we update the
1133 template to do that.
1136 =head1 UPDATING THE VIEW
1138 Let's add a new column to our book list page that takes advantage of
1139 the relationship information we manually added to our schema files
1140 in the previous section. Edit C<root/src/books/list.tt2> add add the
1141 following code below the existing table cell that contains
1142 C<book.rating> (IOW, add a new table cell below the existing two
1146 [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
1147 [% # loop in 'side effect notation' to load just the last names of the -%]
1148 [% # authors into the list. Note that the 'push' TT vmethod does not print -%]
1149 [% # a value, so nothing will be printed here. But, if you have something -%]
1150 [% # in TT that does return a method and you don't want it printed, you -%]
1151 [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%]
1152 [% # call it and discard the return value. -%]
1153 [% tt_authors = [ ];
1154 tt_authors.push(author.last_name) FOREACH author = book.authors %]
1155 [% # Now use a TT 'virtual method' to display the author count in parens -%]
1156 [% # Note the use of the TT filter "| html" to escape dangerous characters -%]
1157 ([% tt_authors.size | html %])
1158 [% # Use another TT vmethod to join & print the names & comma separators -%]
1159 [% tt_authors.join(', ') | html %]
1162 Then hit "Reload" in your browser (note that you don't need to reload
1163 the development server or use the C<-r> option when updating TT
1164 templates) and you should now see the number of authors each book has
1165 along with a comma-separated list of the authors' last names. (If you
1166 didn't leave the development server running from the previous step,
1167 you will obviously need to start it before you can refresh your
1170 If you are still running the development server with C<DBIC_TRACE>
1171 enabled, you should also now see five more C<SELECT> statements in the
1172 debug output (one for each book as the authors are being retrieved by
1175 SELECT me.id, me.title, me.rating FROM books me:
1176 SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '1'
1177 SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '2'
1178 SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '3'
1179 SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '4'
1180 SELECT me.book_id, me.author_id FROM book_authors me WHERE ( me.book_id = ? ): '5'
1182 Also note in C<root/src/books/list.tt2> that we are using "| html", a
1183 type of TT filter, to escape characters such as E<lt> and E<gt> to <
1184 and > and avoid various types of dangerous hacks against your
1185 application. In a real application, you would probably want to put
1186 "| html" at the end of every field where a user has control over the
1187 information that can appear in that field (and can therefore inject
1188 markup or code if you don't "neutralize" those fields). In addition to
1189 "| html", Template Toolkit has a variety of other useful filters that
1190 can found in the documentation for
1191 L<Template::Filters|Template::Filters>.
1194 =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
1196 In some situations, it can be useful to run your application and
1197 display a page without using a browser. Catalyst lets you do this
1198 using the C<scripts/myapp_test.pl> script. Just supply the URL you
1199 wish to display and it will run that request through the normal
1200 controller dispatch logic and use the appropriate view to render the
1201 output (obviously, complex pages may dump a lot of text to your
1202 terminal window). For example, if you type:
1204 $ script/myapp_test.pl "/books/list"
1206 You should get the same text as if you visited
1207 L<http://localhost:3000/books/list> with the normal development server
1208 and asked your browser to view the page source.
1211 =head1 OPTIONAL INFORMATION
1213 B<NOTE: The rest of this part of the tutorial is optional. You can
1214 skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>,
1217 =head2 Using C<RenderView> for the Default View
1219 Once your controller logic has processed the request from a user, it
1220 forwards processing to your view in order to generate the appropriate
1221 response output. Catalyst uses
1222 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by
1223 default to automatically performs this operation. If you look in
1224 C<lib/MyApp/Controller/Root.pm>, you should see the empty
1225 definition for the C<sub end> method:
1227 sub end : ActionClass('RenderView') {}
1229 The following bullet points provide a quick overview of the
1230 C<RenderView> process:
1236 C<Root.pm> is designed to hold application-wide logic.
1240 At the end of a given user request, Catalyst will call the most specific
1241 C<end> method that's appropriate. For example, if the controller for a
1242 request has an C<end> method defined, it will be called. However, if
1243 the controller does not define a controller-specific C<end> method, the
1244 "global" C<end> method in C<Root.pm> will be called.
1248 Because the definition includes an C<ActionClass> attribute, the
1249 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic
1250 will be executed B<after> any code inside the definition of C<sub end>
1251 is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions>
1252 for more information on C<ActionClass>.
1256 Because C<sub end> is empty, this effectively just runs the default
1257 logic in C<RenderView>. However, you can easily extend the
1258 C<RenderView> logic by adding your own code inside the empty method body
1259 (C<{}>) created by the Catalyst Helpers when we first ran the
1260 C<catalyst.pl> to initialize our application. See
1261 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
1262 detailed information on how to extended C<RenderView> in C<sub end>.
1267 =head2 Using The Default Template Name
1269 By default, C<Catalyst::View::TT> will look for a template that uses the
1270 same name as your controller action, allowing you to save the step of
1271 manually specifying the template name in each action. For example, this
1272 would allow us to remove the
1273 C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our
1274 C<list> action in the Books controller. Open
1275 C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line
1276 to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line
1281 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
1286 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
1287 # 'Context' that's used to 'glue together' the various components
1288 # that make up the application
1289 my ($self, $c) = @_;
1291 # Retrieve all of the book records as book model objects and store in the
1292 # stash where they can be accessed by the TT template
1293 $c->stash->{books} = [$c->model('DB::Books')->all];
1295 # Set the TT template to use. You will almost always want to do this
1296 # in your action methods (actions methods respond to user input in
1297 # your controllers).
1298 #$c->stash->{template} = 'books/list.tt2';
1302 You should now be able to restart the development server as per the
1303 previous section and access the L<http://localhost:3000/books/list>
1306 B<NOTE:> Please note that if you use the default template technique,
1307 you will B<not> be able to use either the C<$c-E<gt>forward> or
1308 the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and
1309 Part 9 of the Tutorial).
1312 =head2 Return To A Manually-Specified Template
1314 In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach>
1315 later in the tutorial, you should remove the comment from the
1316 statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>:
1318 $c->stash->{template} = 'books/list.tt2';
1320 Then delete the C<TEMPLATE_EXTENSION> line in
1321 C<lib/MyApp/View/TT.pm>.
1323 You should then be able to restart the development server and
1324 access L<http://localhost:3000/books/list> in the same manner as
1325 with earlier sections.
1330 Kennedy Clark, C<hkclark@gmail.com>
1332 Please report any errors, issues or suggestions to the author. The
1333 most recent version of the Catalyst Tutorial can be found at
1334 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
1336 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
1337 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).