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 out 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 This tells Catalyst to start using one new plugin,
194 L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a
195 stack trace to the standard Catalyst "debug screen" (the screen
196 Catalyst sends to your browser when an error occurs). Be aware that
197 L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
198 browser, not in the console window from which you're running your
199 application, which is where logging output usually goes.
207 C<__PACKAGE__> is just a shorthand way of referencing the name of the
208 package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__>
209 is equivalent to C<MyApp>.
213 You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace>
214 before you put your application into production, but it can be helpful
219 When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can
220 omit C<Catalyst::Plugin::> from the name. Additionally, you can
221 spread the plugin names across multiple lines as shown here, or place
222 them all on one (or more) lines as with the default configuration.
227 =head1 CREATE A CATALYST CONTROLLER
229 As discussed earlier, controllers are where you write methods that
230 interact with user input. Typically, controller methods respond to
231 C<GET> and C<POST> messages from the user's web browser.
233 Use the Catalyst C<create> script to add a controller for book-related
236 $ script/myapp_create.pl controller Books
237 exists "/home/me/MyApp/script/../lib/MyApp/Controller"
238 exists "/home/me/MyApp/script/../t"
239 created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm"
240 created "/home/me/MyApp/script/../t/controller_Books.t"
242 Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Part 2 of
243 the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for
244 each of the three parts of MVC: C<Model>, C<View>, and C<Controller>)
245 and add the following method to the controller:
249 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
254 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
255 # 'Context' that's used to 'glue together' the various components
256 # that make up the application
259 # Retrieve all of the book records as book model objects and store in the
260 # stash where they can be accessed by the TT template
261 # $c->stash->{books} = [$c->model('DB::Books')->all];
262 # But, for now, use this code until we create the model later
263 $c->stash->{books} = '';
265 # Set the TT template to use. You will almost always want to do this
266 # in your action methods (action methods respond to user input in
268 $c->stash->{template} = 'books/list.tt2';
271 B<TIP>: See Appendix 1 for tips on removing the leading spaces when
272 cutting and pasting example code from POD-based documents.
274 Programmers experienced with object-oriented Perl should recognize
275 C<$self> as a reference to the object where this method was called.
276 On the other hand, C<$c> will be new to many Perl programmers who have
277 not used Catalyst before (it's sometimes written as C<$context>). The
278 Context object is automatically passed to all Catalyst components. It
279 is used to pass information between components and provide access to
280 Catalyst and plugin functionality.
282 B<Note:> Catalyst actions are regular Perl methods, but they make use
283 of Nicholas Clark's C<attributes> module (that's the "C<: Local>" next
284 to the C<sub list> in the code above) to provide additional
285 information to the Catalyst dispatcher logic. Many newer Catalyst
286 applications are switching to the use of "Literal" C<:Path> actions
287 and C<Args> attribute in lieu of C<: Local> and C<: Private>. For
288 example, C<sub any_method :Path :Args(0)> can be used instead of C<sub
289 index :Private> (because no path was supplied to C<Path> it matches
290 the "empty" URL in the namespace of that module... the same thing
291 C<sub index> would do) or C<sub list :Path('list') :Args(0)> could be
292 used instead of the C<sub list : Local> above (the C<list> argument to
293 C<Path> would make it match on the URL C<list> under C<books>, the
294 namespace of the current module). See "Action Types" in
295 L<Catalyst::Manual::Intro|Catalyst::Manual::Intro> as well as Part 5
296 of this tutorial (Authentication) for additional information. Another
297 popular but more advanced feature is C<Chained> actions that allow a
298 single URL to "chain together" multiple action method calls, each with
299 an appropriate number of arguments (see
300 L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained> for
304 =head1 CATALYST VIEWS
306 As mentioned in Part 2 of the tutorial, views are where you render
307 output, typically for display in the user's web browser (but also
308 possibly using other display output-generation systems). The code in
309 C<lib/MyApp/View> selects the I<type> of view to use, with the actual
310 rendering template found in the C<root> directory. As with virtually
311 every aspect of Catalyst, options abound when it comes to the specific
312 view technology you adopt inside your application. However, most
313 Catalyst applications use the Template Toolkit, known as TT (for more
314 information on TT, see L<http://www.template-toolkit.org>). Other
315 somewhat popular view technologies include Mason
316 (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and
317 L<HTML::Template> (L<http://html-template.sourceforge.net>).
320 =head2 Create a Catalyst View
322 When using TT for the Catalyst view, there are two main helper scripts:
328 L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>
332 L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>
336 Both are similar, but C<TT> merely creates the C<lib/MyApp/View/TT.pm>
337 file and leaves the creation of any hierarchical template organization
338 entirely up to you. (It also creates a C<t/view_TT.t> file for testing;
339 test cases will be discussed in Part 8.) On the other hand, the
340 C<TTSite> helper creates a modular and hierarchical view layout with
341 separate Template Toolkit (TT) files for common header and footer
342 information, configuration values, a CSS stylesheet, and more.
344 While TTSite is useful to bootstrap a project, most in the Catalyst
345 community recommend that it's easier to learn both Catalyst and
346 Tempalte Toolkit if you use the more basic TT approach. Consequently,
347 this tutorial will use "plain old TT."
349 Enter the following command to enable the C<TT> style of view
350 rendering for this tutorial:
352 $ script/myapp_create.pl view TT TT
353 exists "/home/me/MyApp/script/../lib/MyApp/View"
354 exists "/home/me/MyApp/script/../t"
355 created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm"
356 created "/home/me/MyApp/script/../t/view_TT.t"
358 This simply creates a view called C<TT> (the second 'TT' argument) in
359 a file called C<TT.pm> (the first 'TT' argument). It is now up to you
360 to decide how you want to structure your view layout. For the
361 tutorial, we will start with a very simple TT template to initially
362 demonstrate the concepts, but quickly migrate to a more typical
363 "wrapper page" type of configuration (where the "wrapper" controls the
364 overall "look and feel" of your site from a single file or set of
367 Edit C<lib/MyApp/View/TT.pm> and you should see that the default
368 contents contains something similar to the following:
370 __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt');
372 And update it to match:
375 # Change default TT extension
376 TEMPLATE_EXTENSION => '.tt2',
377 # Set the location for TT files
379 MyApp->path_to( 'root/src' ),
383 B<NOTE:> Make sure to add a comma after '.tt2' outside the single
386 This changes the default extenstion for Template Toolkit from '.tt' to
387 '.tt2' and changes the base directory for your template files from
388 C<root> to C<root/src>.
391 =head2 Create a TT Template Page
393 First create a directory for book-related TT templates:
395 $ mkdir -p root/src/books
397 Then create C<root/src/books/list.tt2> in your editor and enter:
399 [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%]
400 [% # see this "chomping" in your browser because HTML ignores blank lines, but -%]
401 [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
402 [%- # optional, but both the beginning and the ending TT tags support chomping. -%]
404 [% # Provide a title -%]
405 [% META title = 'Book List' -%]
408 <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr>
409 [% # Display each book in a table row %]
410 [% FOREACH book IN books -%]
412 <td>[% book.title %]</td>
413 <td>[% book.rating %]</td>
418 As indicated by the inline comments above, the C<META title> line uses
419 TT's META feature to provide a title to the "wrapper" that we will
420 create later. Meanwhile, the C<FOREACH> loop iterates through each
421 C<book> model object and prints the C<title> and C<rating> fields.
423 If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT
424 code. TT supports a wide variety of directives for "calling" other
425 files, looping, conditional logic, etc. In general, TT simplifies the
426 usual range of Perl operators down to the single dot (C<.>) operator.
427 This applies to operations as diverse as method calls, hash lookups, and
428 list index values (see
429 L<http://search.cpan.org/perldoc?Template::Manual::Variables>
430 for details and examples). In addition to the usual C<Template> module
431 Pod documentation, you can access the TT manual at
432 L<http://search.cpan.org/perldoc?Template::Manual>.
434 B<TIP:> While you can build all sorts of complex logic into your TT
435 templates, you should in general keep the "code" part of your templates
436 as simple as possible. If you need more complex logic, create helper
437 methods in your model that abstract out a set of code into a single call
438 from your TT template. (Note that the same is true of your controller
439 logic as well -- complex sections of code in your controllers should
440 often be pulled out and placed into your model objects.)
443 =head2 Test Run The Application
445 To test your work so far, first start the development server:
447 $ script/myapp_server.pl
449 Then point your browser to L<http://localhost:3000> and you should
450 still get the Catalyst welcome page. Next, change the URL in your
451 browser to L<http://localhost:3000/books/list>. If you have
452 everything working so far, you should see a web page that displays
453 nothing other than our column headers for "Title", "Rating", and
454 "Author(s)" -- we will not see any books until we get the database and
457 If you run into problems getting your application to run correctly, it
458 might be helpful to refer to some of the debugging techniques covered in
459 the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the
463 =head1 CREATE A SQLITE DATABASE
465 In this step, we make a text file with the required SQL commands to
466 create a database table and load some sample data. We will use SQLite,
467 a popular database that is lightweight and easy to use. Open
468 C<myapp01.sql> in your editor and enter:
471 -- Create a very simple database to hold book and author information
474 id INTEGER PRIMARY KEY,
478 -- 'book_authors' is a many-to-many join table between books & authors
479 CREATE TABLE book_authors (
482 PRIMARY KEY (book_id, author_id)
484 CREATE TABLE authors (
485 id INTEGER PRIMARY KEY,
490 --- Load some sample data
492 INSERT INTO books VALUES (1, 'CCSP SNRS Exam Certification Guide', 5);
493 INSERT INTO books VALUES (2, 'TCP/IP Illustrated, Volume 1', 5);
494 INSERT INTO books VALUES (3, 'Internetworking with TCP/IP Vol.1', 4);
495 INSERT INTO books VALUES (4, 'Perl Cookbook', 5);
496 INSERT INTO books VALUES (5, 'Designing with Web Standards', 5);
497 INSERT INTO authors VALUES (1, 'Greg', 'Bastien');
498 INSERT INTO authors VALUES (2, 'Sara', 'Nasseh');
499 INSERT INTO authors VALUES (3, 'Christian', 'Degu');
500 INSERT INTO authors VALUES (4, 'Richard', 'Stevens');
501 INSERT INTO authors VALUES (5, 'Douglas', 'Comer');
502 INSERT INTO authors VALUES (6, 'Tom', 'Christiansen');
503 INSERT INTO authors VALUES (7, 'Nathan', 'Torkington');
504 INSERT INTO authors VALUES (8, 'Jeffrey', 'Zeldman');
505 INSERT INTO book_authors VALUES (1, 1);
506 INSERT INTO book_authors VALUES (1, 2);
507 INSERT INTO book_authors VALUES (1, 3);
508 INSERT INTO book_authors VALUES (2, 4);
509 INSERT INTO book_authors VALUES (3, 5);
510 INSERT INTO book_authors VALUES (4, 6);
511 INSERT INTO book_authors VALUES (4, 7);
512 INSERT INTO book_authors VALUES (5, 8);
514 Then use the following command to build a C<myapp.db> SQLite database:
516 $ sqlite3 myapp.db < myapp01.sql
518 If you need to create the database more than once, you probably want to
519 issue the C<rm myapp.db> command to delete the database before you use
520 the C<sqlite3 myapp.db E<lt> myapp01.sql> command.
522 Once the C<myapp.db> database file has been created and initialized, you
523 can use the SQLite command line environment to do a quick dump of the
528 Enter ".help" for instructions
529 sqlite> select * from books;
530 1|CCSP SNRS Exam Certification Guide|5
531 2|TCP/IP Illustrated, Volume 1|5
532 3|Internetworking with TCP/IP Vol.1|4
534 5|Designing with Web Standards|5
540 $ sqlite3 myapp.db "select * from books"
541 1|CCSP SNRS Exam Certification Guide|5
542 2|TCP/IP Illustrated, Volume 1|5
543 3|Internetworking with TCP/IP Vol.1|4
545 5|Designing with Web Standards|5
547 As with most other SQL tools, if you are using the full "interactive"
548 environment you need to terminate your SQL commands with a ";" (it's not
549 required if you do a single SQL statement on the command line). Use
550 ".q" to exit from SQLite from the SQLite interactive mode and return to
551 your OS command prompt.
554 =head1 DATABASE ACCESS WITH C<DBIx::Class>
556 Catalyst can be used with virtually any form of persistent datastore
557 available via Perl. For example,
558 L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to
559 easily access databases through the traditional Perl C<DBI> interface.
560 However, most Catalyst applications use some form of ORM technology to
561 automatically create and save model objects as they are used. Although
562 Tony Bowden's L<Class::DBI|Class::DBI> has been a popular choice
563 in the past, Matt Trout's L<DBIx::Class|DBIx::Class> (abbreviated
564 as "DBIC") has rapidly emerged as the Perl-based ORM technology of choice.
565 Most new Catalyst applications rely on DBIC, as will this tutorial.
568 =head2 Create a Dynamic DBIC Model
570 Use the C<create=dynamic> model helper option to build a model that
571 dynamically reads your database structure every time the application
574 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=dynamic dbi:SQLite:myapp.db
575 exists "/home/me/MyApp/script/../lib/MyApp/Model"
576 exists "/home/me/MyApp/script/../t"
577 exists "/home/me/MyApp/script/../lib/MyApp"
578 created "/home/me/MyApp/script/../lib/MyApp/Schema.pm"
579 created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
580 created "/home/me/MyApp/script/../t/model_DB.t"
583 C<DB> is the name of the model class to be created by the helper in
584 C<lib/MyApp/Model>. C<DBIC::Schema> is the type of the model to
585 create. C<MyApp::Schema> is the name of the DBIC schema file written
586 to C<lib/MyApp/Schema.pm>. Because we specified C<create=dynamic> to
588 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to
589 dynamically load the schema information from the database every time
590 the application starts. And finally, C<dbi:SQLite:myapp.db> is the
591 standard DBI connect string for use with SQLite.
593 B<NOTE:> Although the C<create=dynamic> option to the DBIC helper
594 makes for a nifty demonstration, is only really suitable for very
595 small applications. After this demonstration, you should almost always
596 use the C<create=static> option that we switch to below.
599 =head1 ENABLE THE MODEL IN THE CONTROLLER
601 Open C<lib/MyApp/Controller/Books.pm> and uncomment the model code we
602 left disabled earlier (uncomment the line containing
603 C<[$c-E<gt>model('DB::Books')-E<gt>all]> and delete the next 2 lines):
607 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
612 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
613 # 'Context' that's used to 'glue together' the various components
614 # that make up the application
617 # Retrieve all of the book records as book model objects and store in the
618 # stash where they can be accessed by the TT template
619 $c->stash->{books} = [$c->model('DB::Books')->all];
621 # Set the TT template to use. You will almost always want to do this
622 # in your action methods (action methods respond to user input in
624 $c->stash->{template} = 'books/list.tt2';
627 B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> uncommented above
628 written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The two
632 =head2 Test Run The Application
634 First, let's enable an environment variable option that causes
635 DBIx::Class to dump the SQL statements it's using to access the database
636 (this option can provide extremely helpful troubleshooting information):
638 $ export DBIC_TRACE=1
640 This assumes you are using BASH as your shell -- adjust accordingly if
641 you are using a different shell (for example, under tcsh, use
642 C<setenv DBIC_TRACE 1>).
644 B<NOTE:> You can also set this in your code using
645 C<$class-E<gt>storage-E<gt>debug(1);>. See
646 L<DBIx::Class::Manual::Troubleshooting> for details (including options
647 to log to file instead of displaying to the Catalyst development server
650 Then launch the Catalyst development server. The log output should
651 display something like:
653 $script/myapp_server.pl
654 [debug] Debug messages enabled
655 [debug] Statistics enabled
656 [debug] Loaded plugins:
657 .----------------------------------------------------------------------------.
658 | Catalyst::Plugin::ConfigLoader 0.20 |
659 | Catalyst::Plugin::StackTrace 0.08 |
660 | Catalyst::Plugin::Static::Simple 0.20 |
661 '----------------------------------------------------------------------------'
663 [debug] Loaded dispatcher "Catalyst::Dispatcher"
664 [debug] Loaded engine "Catalyst::Engine::HTTP"
665 [debug] Found home "/home/me/MyApp"
666 [debug] Loaded Config "/home/me/MyApp/myapp.conf"
667 [debug] Loaded components:
668 .-----------------------------------------------------------------+----------.
670 +-----------------------------------------------------------------+----------+
671 | MyApp::Controller::Books | instance |
672 | MyApp::Controller::Root | instance |
673 | MyApp::Model::DB | instance |
674 | MyApp::Model::DB::Authors | class |
675 | MyApp::Model::DB::BookAuthors | class |
676 | MyApp::Model::DB::Books | class |
677 | MyApp::View::TT | instance |
678 '-----------------------------------------------------------------+----------'
680 [debug] Loaded Private actions:
681 .----------------------+--------------------------------------+--------------.
682 | Private | Class | Method |
683 +----------------------+--------------------------------------+--------------+
684 | /default | MyApp::Controller::Root | default |
685 | /end | MyApp::Controller::Root | end |
686 | /index | MyApp::Controller::Root | index |
687 | /books/index | MyApp::Controller::Books | index |
688 | /books/list | MyApp::Controller::Books | list |
689 '----------------------+--------------------------------------+--------------'
691 [debug] Loaded Path actions:
692 .-------------------------------------+--------------------------------------.
694 +-------------------------------------+--------------------------------------+
697 | /books | /books/index |
698 | /books/list | /books/list |
699 '-------------------------------------+--------------------------------------'
701 [info] MyApp powered by Catalyst 5.7014
702 You can connect to your server at http://localhost:3000
704 B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from
705 the 'base' directory of your application, not inside the C<script>
706 directory itself or it will not be able to locate the C<myapp.db>
707 database file. You can use a fully qualified or a relative path to
708 locate the database file, but we did not specify that when we ran the
709 model helper earlier.
711 Some things you should note in the output above:
717 Catalyst::Model::DBIC::Schema dynamically created three model classes,
718 one to represent each of the three tables in our database
719 (C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>,
720 and C<MyApp::Model::DB::Books>).
724 The "list" action in our Books controller showed up with a path of
729 Point your browser to L<http://localhost:3000> and you should still get
730 the Catalyst welcome page.
732 Next, to view the book list, change the URL in your browser to
733 L<http://localhost:3000/books/list>. You should get a list of the five
734 books loaded by the C<myapp01.sql> script above without any formatting.
735 The rating for each book should appear on each row, but the "Author(s)"
736 column will sitll be blank (we will fill that in later).
738 Also notice in the output of the C<script/myapp_server.pl> that DBIC
739 used the following SQL to retrieve the data:
741 SELECT me.id, me.title, me.rating FROM books me
743 because we enabled DBIC_TRACE.
745 You now have the beginnings of a simple but workable web application.
746 Continue on to future sections and we will develop the application
750 =head1 CREATE A WRAPPER FOR THE VIEW
752 When using TT, you can (and should!) create a wrapper that will
753 literally wrap content around each of your templates. This is
754 certainly useful as you have one main source for changing things that
755 will appear across your entire site/application instead of having to
756 edit many individual files.
759 =head2 Configure TT.pm For The Wrapper
761 In order to create a wrapper, you must first edit your TT view and
762 tell it where to find your wrapper file. Your TT view is located in
763 C<lib/MyApp/View/TT.pm>.
765 Edit C<lib/MyApp/View/TT.pm> and change it to match the following:
768 # Change default TT extension
769 TEMPLATE_EXTENSION => '.tt2',
770 # Set the location for TT files
772 MyApp->path_to( 'root/src' ),
774 # Set to 1 for detailed timer stats in your HTML as comments
776 # This is your wrapper template located in the 'root/src'
777 WRAPPER => 'wrapper.tt2',
781 =head2 Create the Wrapper Template File and Stylesheet
783 Next you need to set up your wrapper template. Basically, you'll want
784 to take the overall layout of your site and put it into this file.
785 For the tutorial, open C<root/src/wrapper.tt2> and input the following:
787 <?xml version="1.0" encoding="UTF-8"?>
788 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
789 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
791 <title>[% template.title or "My Catalyst App!" %]</title>
792 <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" />
798 [%# Your logo could go here -%]
799 <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" />
800 [%# Insert the page title -%]
801 <h1>[% template.title or site.title %]</h1>
808 <li><a href="[% c.uri_for('/books/list') %]">Home</a></li>
809 <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li>
810 <li><a href="mailto:nobody@nowhere.com" title="Contact Us">Contact Us</a></li>
812 </div><!-- end menu -->
815 [%# Status and error messages %]
816 <span class="message">[% status_msg %]</span>
817 <span class="error">[% error_msg %]</span>
818 [%# This is where TT will stick all of your template's contents. -%]
820 </div><!-- end content -->
821 </div><!-- end bodyblock -->
823 <div id="footer">Copyright (c) your name goes here</div>
824 </div><!-- end outter -->
829 Notice the status and error message sections in the code above:
831 <span class="status">[% status_msg %]</span>
832 <span class="error">[% error_msg %]</span>
834 If we set either message in the Catalyst stash (e.g.,
835 C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it
836 will be displayed whenever any view used by that request is rendered.
837 The C<message> and C<error> CSS styles can be customized to suit your
838 needs in the C<root/static/css/main.css> file we create below.
846 The Catalyst stash only lasts for a single HTTP request. If
847 you need to retain information across requests you can use
848 L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
849 Catalyst sessions in the Authentication part of the tutorial).
853 Although it is beyond the scope of this tutorial, you may wish to use
854 a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or
855 Dojo (L<http://www.dojotoolkit.org>).
860 =head3 Create A Basic Stylesheet
862 First create a central location for stylesheets under the static
865 $ mkdir root/static/css
867 Then open the file C<root/static/css/main.css> (the file referenced in
868 the stylesheet href link of our wrapper above) and add the following
887 background-color: #ddd;
893 padding: 0 0 50% 5px;
895 background-color: #ddd;
908 You may wish to check out a "CSS Framework" like Emastic
909 (L<http://code.google.com/p/emastic/>) as a way to quickly
910 provide lots of high-quality CSS functionality.
913 =head2 Test Run The Application
915 Restart the development server and hit "Reload" in your web browser
916 and you should now see a formatted version of our basic book list.
917 Although our wrapper and stylesheet are obviously very simple, you
918 should see how it allows us to control the overall look of an entire
919 website from two central files. To add new pages to the site, just
920 provide a template that fills in the C<content> section of our wrapper
921 template -- the wrapper will provide the overall feel of the page.
924 =head1 A STATIC DATABASE MODEL WITH C<DBIx::Class>
926 =head2 Create Static DBIC Schema Files
928 Unlike the previous DBIC section where we had C<create=dynamic>
929 automatically discover the structure of the database every time the
930 application started, here we will use static schema files for more
931 control. This is typical of most "real world" applications.
933 One option would be to manually create a separate schema file for each
934 table in the database, however, lets use the same
935 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> used
936 earlier with C<create=dynamic> to build the static files for us.
937 First, lets remove the schema file created earlier:
939 $ rm lib/MyApp/Schema.pm
941 Now regenerate the schema using the C<create=static> option:
943 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=static dbi:SQLite:myapp.db
944 exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model"
945 exists "/home/kclark/dev/MyApp/script/../t"
946 Dumping manual schema for MyApp::Schema to directory /home/kclark/dev/MyApp/script/../lib ...
947 Schema dump completed.
948 exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model/DB.pm"
950 We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would
951 have regenerated the same file (note the C<exists> in the output above).
952 If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains
953 a reference to the actual schema file in C<lib/MyApp/Schema.pm>
954 along with the database connect string.
956 If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
958 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base
959 class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is
960 only being used by the helper to load the schema once and then create
961 the static files for us) and C<Schema.pm> only contains a call to the
962 C<load_classes> method. You will also find that C<lib/MyApp/Schema>
963 contains a C<Schema> subdirectory, with one file inside this directory
964 for each of the tables in our simple database (C<Authors.pm>,
965 C<BookAuthors.pm>, and C<Books.pm>). These three files were created
966 based on the information found by
967 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as the
970 The idea with all of the files created under C<lib/MyApp/Schema> by
971 the C<create=static> option is to only edit the files below the C<# DO
972 NOT MODIFY THIS OR ANYTHING ABOVE!> warning. If you place all of your
973 changes below that point in the file, you can regenerate the
974 automatically created information at the top of each file should your
975 database structure get updated.
977 Also note the "flow" of the model information across the various files
978 and directories. Catalyst will initially load the model from
979 C<lib/MyApp/Model/DB.pm>. This file contains a reference to
980 C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally,
981 the call to C<load_classes> in C<Schema.pm> will load each of the
982 table-specific "results source" files from the C<lib/MyApp/Schema>
983 subdirectory. These three table-specific DBIC schema files will then be
984 used to create three table-specific Catalyst models every time the
985 application starts (you can see these three model files listed in
986 the debug output generated when you launch the application).
989 =head2 Updating the Generated DBIC Schema Files
991 Let's manually add some relationship information to the auto-generated
992 schema files. First edit C<lib/MyApp/Schema/Books.pm> and
993 add the following text below the C<# You can replace this text...>
1002 # 1) Name of relationship, DBIC will create accessor with this name
1003 # 2) Name of the model class referenced by this relationship
1004 # 3) Column name in *foreign* table
1005 __PACKAGE__->has_many(book_authors => 'MyApp::Schema::BookAuthors', 'book_id');
1009 # 1) Name of relationship, DBIC will create accessor with this name
1010 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1011 # 3) Name of belongs_to() relationship in model class of has_many() above
1012 # You must already have the has_many() defined to use a many_to_many().
1013 __PACKAGE__->many_to_many(authors => 'book_authors', 'author');
1016 B<Note:> Be careful to put this code I<above> the C<1;> at the end of the
1017 file. As with any Perl package, we need to end the last line with
1018 a statement that evaluates to C<true>. This is customarily done with
1019 C<1;> on a line by itself.
1021 This code defines both a C<has_many> and a C<many_to_many> relationship.
1022 The C<many_to_many> relationship is optional, but it makes it easier to
1023 map a book to its collection of authors. Without it, we would have to
1024 "walk" though the C<book_authors> table as in
1025 C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name>
1026 (we will see examples on how to use DBIC objects in your code soon,
1027 but note that because C<$book-E<gt>book_authors> can return multiple
1028 authors, we have to use C<first> to display a single author).
1029 C<many_to_many> allows us to use the shorter
1030 C<$book-E<gt>authors-E<gt>first-E<gt>last_name>.
1031 Note that you cannot define a C<many_to_many> relationship without
1032 also having the C<has_many> relationship in place.
1034 Then edit C<lib/MyApp/Schema/Authors.pm> and add relationship
1035 information as follows (again, be careful to put in above the C<1;> but
1036 below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment):
1039 # Set relationships:
1044 # 1) Name of relationship, DBIC will create accessor with this name
1045 # 2) Name of the model class referenced by this relationship
1046 # 3) Column name in *foreign* table
1047 __PACKAGE__->has_many(book_author => 'MyApp::Schema::BookAuthors', 'author_id');
1051 # 1) Name of relationship, DBIC will create accessor with this name
1052 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1053 # 3) Name of belongs_to() relationship in model class of has_many() above
1054 # You must already have the has_many() defined to use a many_to_many().
1055 __PACKAGE__->many_to_many(books => 'book_author', 'book');
1057 Finally, do the same for the "join table,"
1058 C<lib/MyApp/Schema/BookAuthors.pm>:
1061 # Set relationships:
1066 # 1) Name of relationship, DBIC will create accessor with this name
1067 # 2) Name of the model class referenced by this relationship
1068 # 3) Column name in *this* table
1069 __PACKAGE__->belongs_to(book => 'MyApp::Schema::Books', 'book_id');
1073 # 1) Name of relationship, DBIC will create accessor with this name
1074 # 2) Name of the model class referenced by this relationship
1075 # 3) Column name in *this* table
1076 __PACKAGE__->belongs_to(author => 'MyApp::Schema::Authors', 'author_id');
1079 =head2 Run The Application
1081 Run the Catalyst "demo server" script with the C<DBIC_TRACE> option
1082 (it might still be enabled from earlier in the tutorial, but here
1083 is an alternate way to specify the option just in case):
1085 $ DBIC_TRACE=1 script/myapp_server.pl
1087 Make sure that the application loads correctly and that you see the
1088 three dynamically created model class (one for each of the
1089 table-specific schema classes we created).
1091 Then hit the URL L<http://localhost:3000/books/list> and be sure that
1092 the book list is displayed.
1094 You can leave the development server running for the next step if you
1098 =head1 UPDATING THE VIEW
1100 Let's add a new column to our book list page that takes advantage of
1101 the relationship information we manually added to our schema files
1102 in the previous section. Edit C<root/src/books/list.tt2> add add the
1103 following code below the existing table cell that contains
1104 C<book.rating> (IOW, add a new table cell below the existing two
1108 [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
1109 [% # loop in 'side effect notation' to load just the last names of the -%]
1110 [% # authors into the list. Note that the 'push' TT vmethod does not print -%]
1111 [% # a value, so nothing will be printed here. But, if you have something -%]
1112 [% # in TT that does return a method and you don't want it printed, you -%]
1113 [% # can: 1) assign it to a bogus value, or 2) use the CALL keyword to -%]
1114 [% # call it and discard the return value. -%]
1115 [% tt_authors = [ ];
1116 tt_authors.push(author.last_name) FOREACH author = book.authors %]
1117 [% # Now use a TT 'virtual method' to display the author count in parens -%]
1118 [% # Note the use of the TT filter "| html" to escape dangerous characters -%]
1119 ([% tt_authors.size | html %])
1120 [% # Use another TT vmethod to join & print the names & comma separators -%]
1121 [% tt_authors.join(', ') | html %]
1124 Then hit "Reload" in your browser (note that you don't need to reload
1125 the development server or use the C<-r> option when updating TT
1126 templates) and you should now see the number of authors each book has
1127 along with a comma-separated list of the authors' last names. (If you
1128 didn't leave the development server running from the previous step,
1129 you will obviously need to start it before you can refresh your
1132 If you are still running the development server with C<DBIC_TRACE>
1133 enabled, you should also now see five more C<SELECT> statements in the
1134 debug output (one for each book as the authors are being retrieved by
1137 Also note that we are using "| html", a type of TT filter, to escape
1138 characters such as E<lt> and E<gt> to < and > and avoid various
1139 types of dangerous hacks against your application. In a real
1140 application, you would probably want to put "| html" at the end of
1141 every field where a user has control over the information that can
1142 appear in that field (and can therefore inject markup or code if you
1143 don't "neutralize" those fields). In addition to "| html", Template
1144 Toolkit has a variety of other useful filters that can found in the
1145 documentation for L<Template::Filters|Template::Filters>.
1148 =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
1150 In some situations, it can be useful to run your application and
1151 display a page without using a browser. Catalyst lets you do this
1152 using the C<scripts/myapp_test.pl> script. Just supply the URL you
1153 wish to display and it will run that request through the normal
1154 controller dispatch logic and use the appropriate view to render the
1155 output (obviously, complex pages may dump a lot of text to your
1156 terminal window). For example, if you type:
1158 $ script/myapp_test.pl "/books/list"
1160 You should get the same text as if you visited
1161 L<http://localhost:3000/books/list> with the normal development server
1162 and asked your browser to view the page source.
1165 =head1 OPTIONAL INFORMATION
1167 B<NOTE: The rest of this part of the tutorial is optional. You can
1168 skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>,
1171 =head2 Using C<RenderView> for the Default View
1173 Once your controller logic has processed the request from a user, it
1174 forwards processing to your view in order to generate the appropriate
1175 response output. Catalyst uses
1176 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by
1177 default to automatically performs this operation. If you look in
1178 C<lib/MyApp/Controller/Root.pm>, you should see the empty
1179 definition for the C<sub end> method:
1181 sub end : ActionClass('RenderView') {}
1183 The following bullet points provide a quick overview of the
1184 C<RenderView> process:
1190 C<Root.pm> is designed to hold application-wide logic.
1194 At the end of a given user request, Catalyst will call the most specific
1195 C<end> method that's appropriate. For example, if the controller for a
1196 request has an C<end> method defined, it will be called. However, if
1197 the controller does not define a controller-specific C<end> method, the
1198 "global" C<end> method in C<Root.pm> will be called.
1202 Because the definition includes an C<ActionClass> attribute, the
1203 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic
1204 will be executed B<after> any code inside the definition of C<sub end>
1205 is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions>
1206 for more information on C<ActionClass>.
1210 Because C<sub end> is empty, this effectively just runs the default
1211 logic in C<RenderView>. However, you can easily extend the
1212 C<RenderView> logic by adding your own code inside the empty method body
1213 (C<{}>) created by the Catalyst Helpers when we first ran the
1214 C<catalyst.pl> to initialize our application. See
1215 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
1216 detailed information on how to extended C<RenderView> in C<sub end>.
1221 =head2 Using The Default Template Name
1223 By default, C<Catalyst::View::TT> will look for a template that uses the
1224 same name as your controller action, allowing you to save the step of
1225 manually specifying the template name in each action. For example, this
1226 would allow us to remove the
1227 C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our
1228 C<list> action in the Books controller. Open
1229 C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line
1230 to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line
1235 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
1240 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
1241 # 'Context' that's used to 'glue together' the various components
1242 # that make up the application
1243 my ($self, $c) = @_;
1245 # Retrieve all of the book records as book model objects and store in the
1246 # stash where they can be accessed by the TT template
1247 $c->stash->{books} = [$c->model('DB::Books')->all];
1249 # Set the TT template to use. You will almost always want to do this
1250 # in your action methods (actions methods respond to user input in
1251 # your controllers).
1252 #$c->stash->{template} = 'books/list.tt2';
1256 You should now be able to restart the development server as per the
1257 previous section and access the L<http://localhost:3000/books/list>
1260 B<NOTE:> Please note that if you use the default template technique,
1261 you will B<not> be able to use either the C<$c-E<gt>forward> or
1262 the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and
1263 Part 9 of the Tutorial).
1266 =head2 Return To A Manually-Specified Template
1268 In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach>
1269 later in the tutorial, you should remove the comment from the
1270 statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>:
1272 $c->stash->{template} = 'books/list.tt2';
1274 Then delete the C<TEMPLATE_EXTENSION> line in
1275 C<lib/MyApp/View/TT.pm>.
1277 You should then be able to restart the development server and
1278 access L<http://localhost:3000/books/list> in the same manner as
1279 with earlier sections.
1284 Kennedy Clark, C<hkclark@gmail.com>
1286 Please report any errors, issues or suggestions to the author. The
1287 most recent version of the Catalyst Tutorial can be found at
1288 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
1290 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
1291 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).