3 Catalyst::Manual::Tutorial::03_MoreCatalystBasics - Catalyst Tutorial - Chapter 3: More Catalyst Application Development Basics
8 This is B<Chapter 3 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::01_Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::02_CatalystBasics>
24 B<03_More Catalyst Basics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::05_Authentication>
36 L<Authorization|Catalyst::Manual::Tutorial::06_Authorization>
40 L<Debugging|Catalyst::Manual::Tutorial::07_Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::08_Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::09_AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::10_Appendices>
59 This chapter of the tutorial builds on the work done in Chapter 2 to
60 explore some features that are more typical of "real world" web
61 applications. From this chapter of the tutorial onward, we will be
62 building a simple book database application. Although the application
63 will be too limited to be of use to anyone, it should provide a basic
64 environment where we can explore a variety of features used in
65 virtually all web applications.
67 You can check out the source code for this example from the Catalyst
68 Subversion repository as per the instructions in
69 L<Catalyst::Manual::Tutorial::01_Intro|Catalyst::Manual::Tutorial::01_Intro>.
72 L<Catalyst::Manual::Tutorial::01_Intro/CATALYST INSTALLATION> before
73 doing the rest of this tutorial. Although the tutorial should work
74 correctly under most any recent version of Perl running on any
75 operating system, the tutorial has been written using Debian 5 and
76 tested to be sure it runs correctly in this environment.
79 =head1 CREATE A NEW APPLICATION
81 The remainder of the tutorial will build an application called C<MyApp>.
82 First use the Catalyst C<catalyst.pl> script to initialize the framework
83 for the C<MyApp> application (make sure you aren't still inside the
84 directory of the C<Hello> application from the previous chapter of the
85 tutorial or in a directory that already has a "MyApp" subdirectory):
89 created "MyApp/script"
93 created "MyApp/script/myapp_create.pl"
94 Change to application directory and Run "perl Makefile.PL" to make sure your install is complete
97 This creates a similar skeletal structure to what we saw in Chapter 2 of
98 the tutorial, except with C<MyApp> and C<myapp> substituted for
99 C<Hello> and C<hello>. (As noted in Chapter 2, omit the ".pl" from
100 the command if you are using Strawberry Perl.)
103 =head1 EDIT THE LIST OF CATALYST PLUGINS
105 One of the greatest benefits of Catalyst is that it has such a large
106 library of plugins and base classes available. Plugins are used to
107 seamlessly integrate existing Perl modules into the overall Catalyst
108 framework. In general, they do this by adding additional methods to the
109 C<context> object (generally written as C<$c>) that Catalyst passes to
110 every component throughout the framework.
112 By default, Catalyst enables three plugins/flags:
120 Enables the Catalyst debug output you saw when we started the
121 C<script/myapp_server.pl> development server earlier. You can remove
122 this item when you place your application into production.
124 To be technically correct, it turns out that C<-Debug> is not a plugin, but a I<flag>.
125 Although most of the items specified on the C<__PACKAGE__-E<gt>setup>
126 line of your application class will be plugins, Catalyst supports a
127 limited number of flag options (of these, C<-Debug> is the most
128 common). See the documentation for C<Catalyst.pm> to get details on
129 other flags (currently C<-Engine>, C<-Home>, and C<-Log>).
131 If you prefer, there are several other ways to enable debug output:
137 Use the C<$c-E<gt>debug> method
141 The C<-d> option to C<script/myapp_server.pl>
145 The C<CATALYST_DEBUG=1> environment variable (or set it to
146 zero to templorarily disable debug output).
150 B<TIP>: Depending on your needs, it can be helpful to permanently
151 remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option
152 to C<script/myapp_server.pl> to re-enable it just for the development
153 server. We will not be using that approach in the tutorial, but feel
154 free to make use of it in your own projects.
158 L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader>
160 C<ConfigLoader> provides an automatic way to load configurable
161 parameters for your application from a central
162 L<Config::General|Config::General> file (versus having the values
163 hard-coded inside your Perl modules). Config::General uses syntax
164 very similar to Apache configuration files. We will see how to use
165 this feature of Catalyst during the authentication and authorization
166 sections (Chapter 5 and Chapter 6).
168 B<IMPORTANT NOTE:> If you are using a version of
169 L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware
170 that Catalyst changed the default format from YAML to the more
171 straightforward C<Config::General> style. This tutorial uses the
172 newer C<myapp.conf> file for C<Config::General>. However, Catalyst
173 supports both formats and will automatically use either C<myapp.conf>
174 or C<myapp.yml> (or any other format supported by
175 L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and
176 L<Config::Any|Config::Any>). If you are using a version of
177 Catalyst::Devel prior to 1.06, you can convert to the newer format by
178 simply creating the C<myapp.conf> file manually and deleting
179 C<myapp.yml>. The default contents of the C<myapp.conf> you create
180 should only consist of one line:
184 B<TIP>: This script can be useful for converting between configuration
187 perl -Ilib -e 'use MyApp; use Config::General;
188 Config::General->new->save_file("myapp.conf", MyApp->config);'
192 L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple>
194 C<Static::Simple> provides an easy way to serve static content, such
195 as images and CSS files, from the development server.
199 For our application, we want to add one new plugin into the mix. To
200 do this, edit C<lib/MyApp.pm> (this file is generally referred to as
201 your I<application class>) and delete the lines with:
209 Then replace it with:
220 B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of
221 techniques to load these plugins/flags. For example, you might see
224 __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/);
226 Don't let these variations confuse you -- they all accomplish the same
229 This tells Catalyst to start using one new plugin,
230 L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a
231 stack trace to the standard Catalyst "debug screen" (the screen
232 Catalyst sends to your browser when an error occurs). Be aware that
233 L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
234 browser, not in the console window from which you're running your
235 application, which is where logging output usually goes.
237 Make sure when adding new plugins you also include them as a new
238 dependency within the Makefile.PL file. For example, after adding
239 the StackTrace plugin the Makefile.PL should include the following
242 requires 'Catalyst::Plugin::StackTrace';
251 C<__PACKAGE__> is just a shorthand way of referencing the name of the
252 package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__>
253 is equivalent to C<MyApp>.
257 You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace>
258 before you put your application into production, but it can be helpful
263 When specifying plugins, you can omit C<Catalyst::Plugin::> from the
264 name. Additionally, you can spread the plugin names across multiple
265 lines as shown here or place them all on one line.
270 =head1 CREATE A CATALYST CONTROLLER
272 As discussed earlier, controllers are where you write methods that
273 interact with user input. Typically, controller methods respond to
274 C<GET> and C<POST> requests from the user's web browser.
276 Use the Catalyst C<create> script to add a controller for book-related
279 $ script/myapp_create.pl controller Books
280 exists "/home/me/MyApp/script/../lib/MyApp/Controller"
281 exists "/home/me/MyApp/script/../t"
282 created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm"
283 created "/home/me/MyApp/script/../t/controller_Books.t"
285 Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of
286 the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for
287 each of the three parts of MVC: C<Model>, C<View>, and C<Controller>)
288 and add the following method to the controller:
292 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
297 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
298 # 'Context' that's used to 'glue together' the various components
299 # that make up the application
302 # Retrieve all of the book records as book model objects and store in the
303 # stash where they can be accessed by the TT template
304 # $c->stash->{books} = [$c->model('DB::Book')->all];
305 # But, for now, use this code until we create the model later
306 $c->stash->{books} = '';
308 # Set the TT template to use. You will almost always want to do this
309 # in your action methods (action methods respond to user input in
311 $c->stash->{template} = 'books/list.tt2';
314 B<TIP>: See Appendix 1 for tips on removing the leading spaces when
315 cutting and pasting example code from POD-based documents.
317 Programmers experienced with object-oriented Perl should recognize
318 C<$self> as a reference to the object where this method was called.
319 On the other hand, C<$c> will be new to many Perl programmers who have
320 not used Catalyst before (it's sometimes written as C<$context>). The
321 Context object is automatically passed to all Catalyst components. It
322 is used to pass information between components and provide access to
323 Catalyst and plugin functionality.
325 Catalyst actions are regular Perl methods, but they make use of
326 attributes (the "C<: Local>" next to the "C<sub list>" in the code
327 above) to provide additional information to the Catalyst dispatcher
328 logic (note that the space between the colon and the attribute name is
329 optional; you will see attributes written both ways). Most Catalyst
330 Controllers use one of five action types:
336 B<:Private> -- Use C<:Private> for methods that you want to make into
337 an action, but you do not want Catalyst to directly expose the method
338 to your users. Catalyst will not map C<:Private> methods to a URI.
339 Use them for various sorts of "special" methods (the C<begin>,
340 C<auto>, etc. discussed below) or for methods you want to be able to
341 C<forward> or C<detach> to. (If the method is a plain old "helper
342 method" that you don't want to be an action at all, then just define
343 the method without any attribute -- you can call it in your code, but
344 the Catalyst dispatcher will ignore it.)
346 There are five types of "special" build-in C<:Private> actions:
347 C<begin>, C<end>, C<default>, C<index>, and C<auto>.
353 With C<begin>, C<end>, C<default>, C<index> private actions, only the
354 most specific action of each type will be called. For example, if you
355 define a C<begin> action in your controller it will I<override> a
356 C<begin> action in your application/root controller -- I<only> the
357 action in your controller will be called.
361 Unlike the other actions where only a single method is called for each
362 request, I<every> auto action along the chain of namespaces will be
363 called. Each C<auto> action will be called I<from the application/root
364 controller down through the most specific class>.
370 B<:Path> -- C<:Path> actions let you map a method to an explicit URI
371 path. For example, "C<:Path('list')>" in
372 C<lib/MyApp/Controller/Books.pm> would match on the URL
373 C<http://localhost:3000/books/list>, but "C<:Path('/list')>" would
374 match on C<http://localhost:3000/list> (because of the leading slash).
375 You can use C<:Args()> to specify how many arguments an action should
376 accept. See L<Catalyst::Manual::Intro/Action_types> for more
377 information and examples.
381 B<:Local> -- C<:Local> is merely a shorthand for
382 "C<:Path('_name_of_method_')>". For example, these are equivalent:
383 "C<sub create_book :Local {...}>" and
384 "C<sub create_book :Path('create_book') {...}>".
388 B<:Global> -- C<:Global> is merely a shorthand for
389 "C<:Path('/_name_of_method_')>". For example, these are equivalent:
390 "C<sub create_book :Global {...}>" and
391 "C<sub create_book :Path('/create_book') {...}>".
395 B<:Chained> -- Newer Catalyst applications tend to use the Chained
396 dispatch form of action types because of its power and flexibility.
397 It allows a series of controller methods to be automatically dispatched
398 to service a single user request. See
399 L<Catalyst::Manual::Tutorial::04_BasicCRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>
400 and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained>
401 for more information on chained actions.
405 You should refer to L<Catalyst::Manual::Intro/Action_types> for
406 additional information and for coverage of some lesser-used action
407 types not discussed here (C<Regex> and C<LocalRegex>).
410 =head1 CATALYST VIEWS
412 As mentioned in Chapter 2 of the tutorial, views are where you render
413 output, typically for display in the user's web browser (but also
414 possibly using into output-generation systems, such as PDF or JSON).
415 The code in C<lib/MyApp/View> selects the I<type> of view to use, with
416 the actual rendering template found in the C<root> directory. As with
417 virtually every aspect of Catalyst, options abound when it comes to the
418 specific view technology you adopt inside your application. However,
419 most Catalyst applications use the Template Toolkit, known as TT (for
420 more information on TT, see L<http://www.template-toolkit.org>). Other
421 somewhat popular view technologies include Mason
422 (L<http://www.masonhq.com> and L<http://www.masonbook.com>) and
423 L<HTML::Template> (L<http://html-template.sourceforge.net>).
426 =head2 Create a Catalyst View
428 When using TT for the Catalyst view, the main helper script
429 is L<Catalyst::Helper::View::TT|Catalyst::Helper::View::TT>.
430 You may also come across references to
431 L<Catalyst::Helper::View::TTSite|Catalyst::Helper::View::TTSite>,
432 but its use is now deprecated.
434 Enter the following command to enable the C<TT> style of view
435 rendering for this tutorial:
437 $ script/myapp_create.pl view TT TT
438 exists "/home/me/MyApp/script/../lib/MyApp/View"
439 exists "/home/me/MyApp/script/../t"
440 created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm"
441 created "/home/me/MyApp/script/../t/view_TT.t"
443 This simply creates a view called C<TT> (the second 'TT' argument) in
444 a file called C<TT.pm> (the first 'TT' argument). It is now up to you
445 to decide how you want to structure your view layout. For the
446 tutorial, we will start with a very simple TT template to initially
447 demonstrate the concepts, but quickly migrate to a more typical
448 "wrapper page" type of configuration (where the "wrapper" controls the
449 overall "look and feel" of your site from a single file or set of
452 Edit C<lib/MyApp/View/TT.pm> and you should see that the default
453 contents contains something similar to the following:
455 __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt');
457 And update it to match:
460 # Change default TT extension
461 TEMPLATE_EXTENSION => '.tt2',
462 # Set the location for TT files
464 MyApp->path_to( 'root', 'src' ),
468 B<NOTE:> Make sure to add a comma after '.tt2' outside the single
471 This changes the default extension for Template Toolkit from '.tt' to
472 '.tt2' and changes the base directory for your template files from
473 C<root> to C<root/src>. Stick with these conventions for the
474 tutorial, but feel free to use whatever options you desire in your
475 applications (as with most things Perl, there's more than one way to
478 B<Note:> We will use C<root/src> as the base directory for our
479 template files, with a full naming convention of
480 C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to
481 use C<root/> as the base (with a full filename pattern of
482 C<root/_controller_name_/_action_name_.tt2>).
485 =head2 Create a TT Template Page
487 First create a directory for book-related TT templates:
489 $ mkdir -p root/src/books
491 Then create C<root/src/books/list.tt2> in your editor and enter:
493 [% # This is a TT comment. The '-' at the end "chomps" the newline. You won't -%]
494 [% # see this "chomping" in your browser because HTML ignores blank lines, but -%]
495 [% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
496 [%- # optional, but both the beginning and the ending TT tags support chomping. -%]
498 [% # Provide a title -%]
499 [% META title = 'Book List' -%]
502 <tr><th>Title</th><th>Rating</th><th>Author(s)</th></tr>
503 [% # Display each book in a table row %]
504 [% FOREACH book IN books -%]
506 <td>[% book.title %]</td>
507 <td>[% book.rating %]</td>
513 As indicated by the inline comments above, the C<META title> line uses
514 TT's META feature to provide a title to the "wrapper" that we will
515 create later. Meanwhile, the C<FOREACH> loop iterates through each
516 C<book> model object and prints the C<title> and C<rating> fields.
518 The C<[%> and C<%]> tags are used to delimit Template Toolkit code. TT
519 supports a wide variety of directives for "calling" other files,
520 looping, conditional logic, etc. In general, TT simplifies the usual
521 range of Perl operators down to the single dot (".") operator. This
522 applies to operations as diverse as method calls, hash lookups, and list
524 L<http://search.cpan.org/perldoc?Template::Manual::Variables> for
525 details and examples). In addition to the usual L<Template> module Pod
526 documentation, you can access the TT manual at
527 L<http://search.cpan.org/perldoc?Template::Manual>.
529 B<TIP:> While you can build all sorts of complex logic into your TT
530 templates, you should in general keep the "code" part of your
531 templates as simple as possible. If you need more complex logic,
532 create helper methods in your model that abstract out a set of code
533 into a single call from your TT template. (Note that the same is true
534 of your controller logic as well -- complex sections of code in your
535 controllers should often be pulled out and placed into your model
536 objects.) In Chapter 4 of the tutorial we will explore some extremely
537 helpful and powerful features of L<DBIx::Class> that allow you to pull
538 code out of your views and controllers and place it where it
539 rightfully belongs in a model class.
542 =head2 Test Run The Application
544 To test your work so far, first start the development server:
546 $ script/myapp_server.pl
548 Then point your browser to L<http://localhost:3000> and you should
549 still get the Catalyst welcome page. Next, change the URL in your
550 browser to L<http://localhost:3000/books/list>. If you have
551 everything working so far, you should see a web page that displays
552 nothing other than our column headers for "Title", "Rating", and
553 "Author(s)" -- we will not see any books until we get the database and
556 If you run into problems getting your application to run correctly, it
557 might be helpful to refer to some of the debugging techniques covered in
558 the L<Debugging|Catalyst::Manual::Tutorial::07_Debugging> chapter of the
562 =head1 CREATE A SQLITE DATABASE
564 In this step, we make a text file with the required SQL commands to
565 create a database table and load some sample data. We will use
566 SQLite (L<http://www.sqlite.org>), a popular database that is
567 lightweight and easy to use. Be sure to get at least version 3. Open
568 C<myapp01.sql> in your editor and enter:
571 -- Create a very simple database to hold book and author information
574 id INTEGER PRIMARY KEY,
578 -- 'book_author' is a many-to-many join table between books & authors
579 CREATE TABLE book_author (
580 book_id INTEGER REFERENCES book(id) ON DELETE CASCADE ON UPDATE CASCADE,
581 author_id INTEGER REFERENCES author(id) ON DELETE CASCADE ON UPDATE CASCADE,
582 PRIMARY KEY (book_id, author_id)
584 CREATE TABLE author (
585 id INTEGER PRIMARY KEY,
590 --- Load some sample data
592 INSERT INTO book VALUES (1, 'CCSP SNRS Exam Certification Guide', 5);
593 INSERT INTO book VALUES (2, 'TCP/IP Illustrated, Volume 1', 5);
594 INSERT INTO book VALUES (3, 'Internetworking with TCP/IP Vol.1', 4);
595 INSERT INTO book VALUES (4, 'Perl Cookbook', 5);
596 INSERT INTO book VALUES (5, 'Designing with Web Standards', 5);
597 INSERT INTO author VALUES (1, 'Greg', 'Bastien');
598 INSERT INTO author VALUES (2, 'Sara', 'Nasseh');
599 INSERT INTO author VALUES (3, 'Christian', 'Degu');
600 INSERT INTO author VALUES (4, 'Richard', 'Stevens');
601 INSERT INTO author VALUES (5, 'Douglas', 'Comer');
602 INSERT INTO author VALUES (6, 'Tom', 'Christiansen');
603 INSERT INTO author VALUES (7, 'Nathan', 'Torkington');
604 INSERT INTO author VALUES (8, 'Jeffrey', 'Zeldman');
605 INSERT INTO book_author VALUES (1, 1);
606 INSERT INTO book_author VALUES (1, 2);
607 INSERT INTO book_author VALUES (1, 3);
608 INSERT INTO book_author VALUES (2, 4);
609 INSERT INTO book_author VALUES (3, 5);
610 INSERT INTO book_author VALUES (4, 6);
611 INSERT INTO book_author VALUES (4, 7);
612 INSERT INTO book_author VALUES (5, 8);
614 Then use the following command to build a C<myapp.db> SQLite database:
616 $ sqlite3 myapp.db < myapp01.sql
618 If you need to create the database more than once, you probably want to
619 issue the C<rm myapp.db> command to delete the database before you use
620 the C<sqlite3 myapp.db E<lt> myapp01.sql> command.
622 Once the C<myapp.db> database file has been created and initialized, you
623 can use the SQLite command line environment to do a quick dump of the
628 Enter ".help" for instructions
629 sqlite> select * from book;
630 1|CCSP SNRS Exam Certification Guide|5
631 2|TCP/IP Illustrated, Volume 1|5
632 3|Internetworking with TCP/IP Vol.1|4
634 5|Designing with Web Standards|5
640 $ sqlite3 myapp.db "select * from book"
641 1|CCSP SNRS Exam Certification Guide|5
642 2|TCP/IP Illustrated, Volume 1|5
643 3|Internetworking with TCP/IP Vol.1|4
645 5|Designing with Web Standards|5
647 As with most other SQL tools, if you are using the full "interactive"
648 environment you need to terminate your SQL commands with a ";" (it's not
649 required if you do a single SQL statement on the command line). Use
650 ".q" to exit from SQLite from the SQLite interactive mode and return to
651 your OS command prompt.
653 Please note that here we have chosen to use 'singular' table names. This is
654 because the default inflection code for older versions
655 L<DBIx::Class::Schema::Loader> does NOT handle plurals. There has been much
656 philosophical discussion on whether table names should be plural or singular.
657 There is no one correct answer, as long as one makes a choice and remains
658 consistent with it. If you prefer plural table names (e.g. you think that they
659 are easier to read) then see the documentation in
660 L<DBIx::Class::Schema::Loader::Base/naming> (version 0.05 or greater).
662 For using other databases, such as PostgreSQL or MySQL, see
663 L<Appendix 2|Catalyst::Manual::Tutorial::10_Appendices>.
666 =head1 DATABASE ACCESS WITH DBIx::Class
668 Catalyst can be used with virtually any form of datastore available
669 via Perl. For example, L<Catalyst::Model::DBI|Catalyst::Model::DBI>
670 can be used to access databases through the traditional Perl L<DBI>
671 interface or you can use a model to access files of any type on the
672 filesystem. However, most Catalyst applications use some form of
673 object-relational mapping (ORM) technology to create objects
674 associated with tables in a relational database. Matt Trout's
675 L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly emerged
676 as the Perl-based ORM technology of choice. Most new Catalyst
677 applications rely on DBIx::Class, as will this tutorial.
679 Although DBIx::Class has included support for a C<create=dynamic> mode
680 to automatically read the database structure every time the
681 application starts, it's use is no longer recommended. While it can
682 make for "flashy" demos, the use of the C<create=static> mode we use
683 below can be implemented just as quickly and provides many advantages
684 (such as the ability to add your own methods to the overall DBIC
685 framework, a technique that we see in Chapter 4).
688 =head2 Make Sure You Have a Recent Version of the DBIx::Class Model
690 First, let's be sure we have a recent version of the DBIC helper,
691 L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by
692 running this command:
694 $ perl -MCatalyst::Model::DBIC::Schema -e \
695 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"'
698 Please note the '\' above. Depending on your environment, you might
699 be able to cut and paste the text as shown or need to remove the '\'
700 character to that the command is all on a single line.
702 You should have version 0.31 or greater if you are following along
703 with Debian 5. In other environments, you may need to run this
704 command to install it directly from CPAN:
706 $ sudo cpan Catalyst::Model::DBIC::Schema
708 And re-run the version print command to verify that you are now at
711 Please use version C<1.27> of L<DBD::SQLite> or later for proper foreign key
714 =head2 Create Static DBIx::Class Schema Files
716 Before you continue, make sure your C<myapp.db> database file is in
717 the application's topmost directory. Now use the model helper with
718 the C<create=static> option to read the database with
719 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> and
720 automatically build the required files for us:
722 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
723 create=static dbi:SQLite:myapp.db \
724 on_connect_do="PRAGMA foreign_keys = ON"
725 exists "/home/me/MyApp/script/../lib/MyApp/Model"
726 exists "/home/me/MyApp/script/../t"
727 Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ...
728 Schema dump completed.
729 created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
730 created "/home/me/MyApp/script/../t/model_DB.t"
732 Please note the '\' above. Depending on your environment, you might
733 be able to cut and paste the text as shown or need to remove the '\'
734 character to that the command is all on a single line.
736 The C<script/myapp_create.pl> command breaks down like this:
742 C<DB> is the name of the model class to be created by the helper in
747 C<DBIC::Schema> is the type of the model to create.
751 C<MyApp::Schema> is the name of the DBIC schema file written to
752 C<lib/MyApp/Schema.pm>.
756 C<create=static> causes
757 L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to
758 load the schema as it runs and then write that information out
763 And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string
768 If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
769 only contains a call to the C<load_namespaces> method. You will also
770 find that C<lib/MyApp> contains a C<Schema> subdirectory, which then
771 has a subdirectory called "Result". This "Result" subdirectory then
772 has files named according to each of the tables in our simple database
773 (C<Author.pm>, C<BookAuthor.pm>, and C<Book.pm>). These three
774 files are called "Result Classes" in DBIx::Class nomenclature. Although the
775 Result Class files are named after tables in our database, the classes
776 correspond to the I<row-level data> that is returned by DBIC (more on
777 this later, especially in
778 L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>).
780 The idea with the Result Source files created under
781 C<lib/MyApp/Schema/Result> by the C<create=static> option is to only
782 edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!>
783 warning. If you place all of your changes below that point in the
784 file, you can regenerate the automatically created information at the
785 top of each file should your database structure get updated.
787 Also note the "flow" of the model information across the various files
788 and directories. Catalyst will initially load the model from
789 C<lib/MyApp/Model/DB.pm>. This file contains a reference to
790 C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the
791 call to C<load_namespaces> in C<Schema.pm> will load each of the
792 "Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory.
793 The final outcome is that Catalyst will dynamically create three
794 table-specific Catalyst models every time the application starts (you
795 can see these three model files listed in the debug output generated
796 when you launch the application).
798 B<NOTE:> Older versions of
799 L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the
800 deprecated DBIx::Class C<load_classes> technique instead of the newer
801 C<load_namspaces>. For new applications, please try to use
802 C<load_namespaces> since it more easily supports a very useful DBIC
803 technique called "ResultSet Classes." If you need to convert an
804 existing application from "load_classes" to "load_namespaces," you can
805 use this process to automate the migration, but first make sure you have
806 version C<0.39> of L<Catalyst::Model::DBIC::Schema> and
807 L<DBIx::Class::Schema::Loader> version C<0.05000> or later.
809 $ # Re-run the helper to upgrade for you
810 $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
811 create=static naming=current use_namespaces=1 \
812 dbi:SQLite:myapp.db \
813 on_connect_do="PRAGMA foreign_keys = ON"
815 =head1 ENABLE THE MODEL IN THE CONTROLLER
817 Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we
818 left disabled earlier so that your version matches the following (un-
819 comment the line containing C<[$c-E<gt>model('DB::Book')-E<gt>all]>
820 and delete the next 2 lines):
824 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
829 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
830 # 'Context' that's used to 'glue together' the various components
831 # that make up the application
834 # Retrieve all of the book records as book model objects and store in the
835 # stash where they can be accessed by the TT template
836 $c->stash->{books} = [$c->model('DB::Book')->all];
838 # Set the TT template to use. You will almost always want to do this
839 # in your action methods (action methods respond to user input in
841 $c->stash->{template} = 'books/list.tt2';
844 B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> un-commented
845 above written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The
846 two are equivalent. Either way, C<$c-E<gt>model> returns a
847 L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries
848 against the database and iterating over the set of results that is
851 We are using the C<-E<gt>all> to fetch all of the books. DBIC
852 supports a wide variety of more advanced operations to easily do
853 things like filtering and sorting the results. For example, the
854 following could be used to sort the results by descending title:
856 $c->model('DB::Book')->search({}, {order_by => 'title DESC'});
858 Some other examples are provided in
859 L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with
860 additional information found at L<DBIx::Class::ResultSet/search>,
861 L<DBIx::Class::Manual::FAQ/Searching>,
862 L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro>
863 and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>.
866 =head2 Test Run The Application
868 First, let's enable an environment variable that causes DBIx::Class to
869 dump the SQL statements used to access the database. This is a
870 helpful trick when you are trying to debug your database-oriented
873 $ export DBIC_TRACE=1
875 This assumes you are using bash as your shell -- adjust accordingly if
876 you are using a different shell (for example, under tcsh, use
877 C<setenv DBIC_TRACE 1>).
879 B<NOTE:> You can also set this in your code using
880 C<$class-E<gt>storage-E<gt>debug(1);>. See
881 L<DBIx::Class::Manual::Troubleshooting> for details (including options
882 to log to a file instead of displaying to the Catalyst development server
885 Then launch the Catalyst development server. The log output should
886 display something like:
888 $ script/myapp_server.pl
889 [debug] Debug messages enabled
890 [debug] Statistics enabled
891 [debug] Loaded plugins:
892 .----------------------------------------------------------------------------.
893 | Catalyst::Plugin::ConfigLoader 0.27 |
894 | Catalyst::Plugin::StackTrace 0.11 |
895 | Catalyst::Plugin::Static::Simple 0.25 |
896 '----------------------------------------------------------------------------'
898 [debug] Loaded dispatcher "Catalyst::Dispatcher"
899 [debug] Loaded engine "Catalyst::Engine::HTTP"
900 [debug] Found home "/home/me/MyApp"
901 [debug] Loaded Config "/home/me/MyApp/myapp.conf"
902 [debug] Loaded components:
903 .-----------------------------------------------------------------+----------.
905 +-----------------------------------------------------------------+----------+
906 | MyApp::Controller::Books | instance |
907 | MyApp::Controller::Root | instance |
908 | MyApp::Model::DB | instance |
909 | MyApp::Model::DB::Author | class |
910 | MyApp::Model::DB::Book | class |
911 | MyApp::Model::DB::BookAuthor | class |
912 | MyApp::View::TT | instance |
913 '-----------------------------------------------------------------+----------'
915 [debug] Loaded Private actions:
916 .----------------------+--------------------------------------+--------------.
917 | Private | Class | Method |
918 +----------------------+--------------------------------------+--------------+
919 | /default | MyApp::Controller::Root | default |
920 | /end | MyApp::Controller::Root | end |
921 | /index | MyApp::Controller::Root | index |
922 | /books/index | MyApp::Controller::Books | index |
923 | /books/list | MyApp::Controller::Books | list |
924 '----------------------+--------------------------------------+--------------'
926 [debug] Loaded Path actions:
927 .-------------------------------------+--------------------------------------.
929 +-------------------------------------+--------------------------------------+
932 | /books | /books/index |
933 | /books/list | /books/list |
934 '-------------------------------------+--------------------------------------'
936 [info] MyApp powered by Catalyst 5.80013
937 You can connect to your server at http://debian:3000
939 B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from
940 the 'base' directory of your application, not inside the C<script>
941 directory itself or it will not be able to locate the C<myapp.db>
942 database file. You can use a fully qualified or a relative path to
943 locate the database file, but we did not specify that when we ran the
944 model helper earlier.
946 Some things you should note in the output above:
952 Catalyst::Model::DBIC::Schema dynamically created three model classes,
953 one to represent each of the three tables in our database
954 (C<MyApp::Model::DB::Author>, C<MyApp::Model::DB::BookAuthor>,
955 and C<MyApp::Model::DB::Book>).
959 The "list" action in our Books controller showed up with a path of
964 Point your browser to L<http://localhost:3000> and you should still get
965 the Catalyst welcome page.
967 Next, to view the book list, change the URL in your browser to
968 L<http://localhost:3000/books/list>. You should get a list of the five
969 books loaded by the C<myapp01.sql> script above without any formatting.
970 The rating for each book should appear on each row, but the "Author(s)"
971 column will still be blank (we will fill that in later).
973 Also notice in the output of the C<script/myapp_server.pl> that
974 DBIx::Class used the following SQL to retrieve the data:
976 SELECT me.id, me.title, me.rating FROM book me
978 because we enabled DBIC_TRACE.
980 You now have the beginnings of a simple but workable web application.
981 Continue on to future sections and we will develop the application
985 =head1 CREATE A WRAPPER FOR THE VIEW
987 When using TT, you can (and should) create a wrapper that will
988 literally wrap content around each of your templates. This is
989 certainly useful as you have one main source for changing things that
990 will appear across your entire site/application instead of having to
991 edit many individual files.
994 =head2 Configure TT.pm For The Wrapper
996 In order to create a wrapper, you must first edit your TT view and
997 tell it where to find your wrapper file.
999 Edit you TT view in C<lib/MyApp/View/TT.pm> and change it to match the
1002 __PACKAGE__->config(
1003 # Change default TT extension
1004 TEMPLATE_EXTENSION => '.tt2',
1005 # Set the location for TT files
1007 MyApp->path_to( 'root', 'src' ),
1009 # Set to 1 for detailed timer stats in your HTML as comments
1011 # This is your wrapper template located in the 'root/src'
1012 WRAPPER => 'wrapper.tt2',
1016 =head2 Create the Wrapper Template File and Stylesheet
1018 Next you need to set up your wrapper template. Basically, you'll want
1019 to take the overall layout of your site and put it into this file.
1020 For the tutorial, open C<root/src/wrapper.tt2> and input the following:
1022 <?xml version="1.0" encoding="UTF-8"?>
1023 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
1024 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
1026 <title>[% template.title or "My Catalyst App!" %]</title>
1027 <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" />
1033 [%# Your logo could go here -%]
1034 <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" />
1035 [%# Insert the page title -%]
1036 <h1>[% template.title or site.title %]</h1>
1039 <div id="bodyblock">
1043 <li><a href="[% c.uri_for('/books/list') %]">Home</a></li>
1044 <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li>
1046 </div><!-- end menu -->
1049 [%# Status and error messages %]
1050 <span class="message">[% status_msg %]</span>
1051 <span class="error">[% error_msg %]</span>
1052 [%# This is where TT will stick all of your template's contents. -%]
1054 </div><!-- end content -->
1055 </div><!-- end bodyblock -->
1057 <div id="footer">Copyright (c) your name goes here</div>
1058 </div><!-- end outer -->
1063 Notice the status and error message sections in the code above:
1065 <span class="status">[% status_msg %]</span>
1066 <span class="error">[% error_msg %]</span>
1068 If we set either message in the Catalyst stash (e.g.,
1069 C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it
1070 will be displayed whenever any view used by that request is rendered.
1071 The C<message> and C<error> CSS styles can be customized to suit your
1072 needs in the C<root/static/css/main.css> file we create below.
1080 The Catalyst stash only lasts for a single HTTP request. If
1081 you need to retain information across requests you can use
1082 L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
1083 Catalyst sessions in the Authentication chapter of the tutorial).
1087 Although it is beyond the scope of this tutorial, you may wish to use
1088 a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or
1089 Dojo (L<http://www.dojotoolkit.org>).
1094 =head3 Create A Basic Stylesheet
1096 First create a central location for stylesheets under the static
1099 $ mkdir root/static/css
1101 Then open the file C<root/static/css/main.css> (the file referenced in
1102 the stylesheet href link of our wrapper above) and add the following
1121 background-color: #ddd;
1127 padding: 0 0 50% 5px;
1128 font-weight: normal;
1129 background-color: #ddd;
1142 You may wish to check out a "CSS Framework" like Emastic
1143 (L<http://code.google.com/p/emastic/>) as a way to quickly
1144 provide lots of high-quality CSS functionality.
1147 =head2 Test Run The Application
1149 Restart the development server and hit "Reload" in your web browser
1150 and you should now see a formatted version of our basic book list.
1151 Although our wrapper and stylesheet are obviously very simple, you
1152 should see how it allows us to control the overall look of an entire
1153 website from two central files. To add new pages to the site, just
1154 provide a template that fills in the C<content> section of our wrapper
1155 template -- the wrapper will provide the overall feel of the page.
1158 =head2 Updating the Generated DBIx::Class Result Class Files
1160 Let's manually add some relationship information to the auto-generated
1161 Result Class files. C<many_to_many> relationships are not currently
1162 automatically generated by L<DBIx::Class::Schema::Loader>.
1163 First edit C<lib/MyApp/Schema/Result/Book.pm> and add the
1164 following text below the C<# You can replace this text...> comment:
1168 # 1) Name of relationship, DBIC will create accessor with this name
1169 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1170 # 3) Name of belongs_to() relationship in model class of has_many() above
1171 # You must already have the has_many() defined to use a many_to_many().
1172 __PACKAGE__->many_to_many(authors => 'book_authors', 'author');
1174 B<Note:> Be careful to put this code I<above> the C<1;> at the end of the
1175 file. As with any Perl package, we need to end the last line with
1176 a statement that evaluates to C<true>. This is customarily done with
1177 C<1;> on a line by itself.
1179 You'll notice there is already a C<has_many> relationship called
1180 C<book_authors>. The C<many_to_many> relationship is optional, but it makes it
1181 easier to map a book to its collection of authors. Without
1182 it, we would have to "walk" though the C<book_author> table as in
1183 C<$book-E<gt>book_author-E<gt>first-E<gt>author-E<gt>last_name> (we
1184 will see examples on how to use DBIx::Class objects in your code soon,
1185 but note that because C<$book-E<gt>book_author> can return multiple
1186 authors, we have to use C<first> to display a single author).
1187 C<many_to_many> allows us to use the shorter
1188 C<$book-E<gt>author-E<gt>first-E<gt>last_name>. Note that you cannot
1189 define a C<many_to_many> relationship without also having the
1190 C<has_many> relationship in place.
1192 Then edit C<lib/MyApp/Schema/Result/Author.pm> and add relationship
1193 information as follows (again, be careful to put in above the C<1;> but
1194 below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment):
1198 # 1) Name of relationship, DBIC will create accessor with this name
1199 # 2) Name of has_many() relationship this many_to_many() is shortcut for
1200 # 3) Name of belongs_to() relationship in model class of has_many() above
1201 # You must already have the has_many() defined to use a many_to_many().
1202 __PACKAGE__->many_to_many(books => 'book_authors', 'book');
1204 =head2 Run The Application
1206 Run the Catalyst development server script with the C<DBIC_TRACE> option
1207 (it might still be enabled from earlier in the tutorial, but here is an
1208 alternate way to specify the option just in case):
1210 $ DBIC_TRACE=1 script/myapp_server.pl
1212 Make sure that the application loads correctly and that you see the
1213 three dynamically created model class (one for each of the
1214 Result Classes we created).
1216 Then hit the URL L<http://localhost:3000/books/list> with your browser
1217 and be sure that the book list still displays correctly. You can leave
1218 the development server running for the next step if you wish.
1220 B<Note:> You will not see the authors yet because the view does not yet
1221 use the new relations. Read on to the next section where we update the
1222 template to do that.
1225 =head1 UPDATING THE VIEW
1227 Let's add a new column to our book list page that takes advantage of
1228 the relationship information we manually added to our schema files in
1229 the previous section. Edit C<root/src/books/list.tt2> and replace
1230 the "empty" table cell "<td></td>" with the following:
1234 [% # NOTE: See Chapter 4 for a better way to do this! -%]
1235 [% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
1236 [% # loop in 'side effect notation' to load just the last names of the -%]
1237 [% # authors into the list. Note that the 'push' TT vmethod doesn't return -%]
1238 [% # a value, so nothing will be printed here. But, if you have something -%]
1239 [% # in TT that does return a value and you don't want it printed, you -%]
1240 [% # 1) assign it to a bogus value, or -%]
1241 [% # 2) use the CALL keyword to call it and discard the return value. -%]
1242 [% tt_authors = [ ];
1243 tt_authors.push(author.last_name) FOREACH author = book.authors %]
1244 [% # Now use a TT 'virtual method' to display the author count in parens -%]
1245 [% # Note the use of the TT filter "| html" to escape dangerous characters -%]
1246 ([% tt_authors.size | html %])
1247 [% # Use another TT vmethod to join & print the names & comma separators -%]
1248 [% tt_authors.join(', ') | html %]
1252 B<IMPORTANT NOTE:> Again, you should keep as much "logic code" as
1253 possible out of your views. This kind of logic belongs in your model
1254 (the same goes for controllers -- keep them as "thin" as possible and
1255 push all of the "complicated code" out to your model objects). Avoid
1256 code like you see in the previous example -- we are only using it here
1257 to show some extra features in TT until we get to the more advanced
1258 model features we will see in Chapter 4 (see
1259 L<Catalyst::Manual::Tutorial::04_BasicCRUD/EXPLORING THE POWER OF DBIC>).
1261 Then hit "Reload" in your browser (note that you don't need to reload
1262 the development server or use the C<-r> option when updating TT
1263 templates) and you should now see the number of authors each book has
1264 along with a comma-separated list of the authors' last names. (If you
1265 didn't leave the development server running from the previous step,
1266 you will obviously need to start it before you can refresh your
1269 If you are still running the development server with C<DBIC_TRACE>
1270 enabled, you should also now see five more C<SELECT> statements in the
1271 debug output (one for each book as the authors are being retrieved by
1274 SELECT me.id, me.title, me.rating FROM book me:
1275 SELECT author.id, author.first_name, author.last_name FROM book_author me
1276 JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '1'
1277 SELECT author.id, author.first_name, author.last_name FROM book_author me
1278 JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '2'
1279 SELECT author.id, author.first_name, author.last_name FROM book_author me
1280 JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '3'
1281 SELECT author.id, author.first_name, author.last_name FROM book_author me
1282 JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '4'
1283 SELECT author.id, author.first_name, author.last_name FROM book_author me
1284 JOIN author author ON author.id = me.author_id WHERE ( me.book_id = ? ): '5'
1286 Also note in C<root/src/books/list.tt2> that we are using "| html", a
1287 type of TT filter, to escape characters such as E<lt> and E<gt> to <
1288 and > and avoid various types of dangerous hacks against your
1289 application. In a real application, you would probably want to put
1290 "| html" at the end of every field where a user has control over the
1291 information that can appear in that field (and can therefore inject
1292 markup or code if you don't "neutralize" those fields). In addition to
1293 "| html", Template Toolkit has a variety of other useful filters that
1294 can found in the documentation for
1295 L<Template::Filters|Template::Filters>.
1298 =head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
1300 In some situations, it can be useful to run your application and
1301 display a page without using a browser. Catalyst lets you do this
1302 using the C<scripts/myapp_test.pl> script. Just supply the URL you
1303 wish to display and it will run that request through the normal
1304 controller dispatch logic and use the appropriate view to render the
1305 output (obviously, complex pages may dump a lot of text to your
1306 terminal window). For example, if you type:
1308 $ script/myapp_test.pl "/books/list"
1310 You should get the same text as if you visited
1311 L<http://localhost:3000/books/list> with the normal development server
1312 and asked your browser to view the page source.
1315 =head1 OPTIONAL INFORMATION
1317 B<NOTE: The rest of this chapter of the tutorial is optional. You can
1318 skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::04_BasicCRUD>,
1322 =head2 Using 'RenderView' for the Default View
1324 Once your controller logic has processed the request from a user, it
1325 forwards processing to your view in order to generate the appropriate
1326 response output. Catalyst uses
1327 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by
1328 default to automatically perform this operation. If you look in
1329 C<lib/MyApp/Controller/Root.pm>, you should see the empty
1330 definition for the C<sub end> method:
1332 sub end : ActionClass('RenderView') {}
1334 The following bullet points provide a quick overview of the
1335 C<RenderView> process:
1341 C<Root.pm> is designed to hold application-wide logic.
1345 At the end of a given user request, Catalyst will call the most specific
1346 C<end> method that's appropriate. For example, if the controller for a
1347 request has an C<end> method defined, it will be called. However, if
1348 the controller does not define a controller-specific C<end> method, the
1349 "global" C<end> method in C<Root.pm> will be called.
1353 Because the definition includes an C<ActionClass> attribute, the
1354 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> logic
1355 will be executed B<after> any code inside the definition of C<sub end>
1356 is run. See L<Catalyst::Manual::Actions|Catalyst::Manual::Actions>
1357 for more information on C<ActionClass>.
1361 Because C<sub end> is empty, this effectively just runs the default
1362 logic in C<RenderView>. However, you can easily extend the
1363 C<RenderView> logic by adding your own code inside the empty method body
1364 (C<{}>) created by the Catalyst Helpers when we first ran the
1365 C<catalyst.pl> to initialize our application. See
1366 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
1367 detailed information on how to extend C<RenderView> in C<sub end>.
1372 =head2 RenderView's "dump_info" Feature
1374 One of the nice features of C<RenderView> is that it automatically
1375 allows you to add C<dump_info=1> to the end of any URL for your
1376 application and it will force the display of the "exception dump"
1377 screen to the client browser. You can try this out by starting the
1378 development server as before and then point your browser to this URL:
1380 http://localhost:3000/books/list?dump_info=1
1382 You should get a page with the following message at the top:
1384 Caught exception in MyApp::Controller::Root->end "Forced debug -
1385 Scrubbed output at /usr/share/perl5/Catalyst/Action/RenderView.pm line 46."
1387 Along with a summary of your application's state at the end of the
1388 processing for that request. The "Stash" section should show a
1389 summarized version of the DBIC book model objects. If desired, you
1390 can adjust the summarization logic (called "scrubbing" logic) -- see
1391 L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for
1394 Note that you shouldn't need to worry about "normal clients" using
1395 this technique to "reverse engineer" your application -- C<RenderView>
1396 only supports the C<dump_info=1> feature when your application is
1397 running in C<-Debug> mode (something you won't do once you have your
1398 application deployed in production).
1401 =head2 Using The Default Template Name
1403 By default, C<Catalyst::View::TT> will look for a template that uses the
1404 same name as your controller action, allowing you to save the step of
1405 manually specifying the template name in each action. For example, this
1406 would allow us to remove the
1407 C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our
1408 C<list> action in the Books controller. Open
1409 C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line
1410 to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line
1415 Fetch all book objects and pass to books/list.tt2 in stash to be displayed
1420 # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
1421 # 'Context' that's used to 'glue together' the various components
1422 # that make up the application
1423 my ($self, $c) = @_;
1425 # Retrieve all of the book records as book model objects and store in the
1426 # stash where they can be accessed by the TT template
1427 $c->stash->{books} = [$c->model('DB::Book')->all];
1429 # Set the TT template to use. You will almost always want to do this
1430 # in your action methods (actions methods respond to user input in
1431 # your controllers).
1432 #$c->stash->{template} = 'books/list.tt2';
1436 You should now be able to restart the development server as per the
1437 previous section and access the L<http://localhost:3000/books/list>
1440 B<NOTE:> Please note that if you use the default template technique,
1441 you will B<not> be able to use either the C<$c-E<gt>forward> or
1442 the C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and
1443 Chapter 9 of the Tutorial).
1445 B<IMPORTANT:> Make sure that you do NOT skip the following section
1446 before continuing to the next chapter 4 Basic CRUD.
1449 =head2 Return To A Manually Specified Template
1451 In order to be able to use C<$c-E<gt>forward> and C<$c-E<gt>detach>
1452 later in the tutorial, you should remove the comment from the
1453 statement in C<sub list> in C<lib/MyApp/Controller/Books.pm>:
1455 $c->stash->{template} = 'books/list.tt2';
1457 Then delete the C<TEMPLATE_EXTENSION> line in
1458 C<lib/MyApp/View/TT.pm>.
1460 You should then be able to restart the development server and
1461 access L<http://localhost:3000/books/list> in the same manner as
1462 with earlier sections.
1467 Kennedy Clark, C<hkclark@gmail.com>
1469 Please report any errors, issues or suggestions to the author. The
1470 most recent version of the Catalyst Tutorial can be found at
1471 L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.80/trunk/lib/Catalyst/Manual/Tutorial/>.
1473 Copyright 2006-2008, Kennedy Clark, under Creative Commons License
1474 (L<http://creativecommons.org/licenses/by-sa/3.0/us/>).