=head1 NAME
-Catalyst::Manual::Tutorial::MoreCatalystBasics - Catalyst Tutorial - Part 3: More Catalyst Application Development Basics
+Catalyst::Manual::Tutorial::MoreCatalystBasics - Catalyst Tutorial - Chapter 3: More Catalyst Application Development Basics
=head1 OVERVIEW
-This is B<Part 3 of 10> for the Catalyst tutorial.
+This is B<Chapter 3 of 10> for the Catalyst tutorial.
L<Tutorial Overview|Catalyst::Manual::Tutorial>
=head1 DESCRIPTION
-This part of the tutorial builds on the work done in Part 2 to explore
-some features that are more typical of "real world" web applications.
-From this part of the tutorial onward, we will be building a simple
-book database application. Although the application will be too
-limited to be of use to anyone, it should provide a basic environment
-where we can explore a variety of features used in virtually all web
-applications.
+This chapter of the tutorial builds on the work done in Chapter 2 to
+explore some features that are more typical of "real world" web
+applications. From this chapter of the tutorial onward, we will be
+building a simple book database application. Although the application
+will be too limited to be of use to anyone, it should provide a basic
+environment where we can explore a variety of features used in
+virtually all web applications.
You can checkout the source code for this example from the catalyst
subversion repository as per the instructions in
-L<Catalyst::Manual::Tutorial::Intro>
+L<Catalyst::Manual::Tutorial::Intro|Catalyst::Manual::Tutorial::Intro>.
=head1 CREATE A NEW APPLICATION
-The remainder of the tutorial will build an application call C<MyApp>.
-Use the Catalyst C<catalyst.pl> script to initialize the framework for
-an application called C<MyApp> (make sure you aren't still inside the
-directory of the C<Hello> application from the previous part of the
-tutorial):
+The remainder of the tutorial will build an application called C<MyApp>.
+First use the Catalyst C<catalyst.pl> script to initialize the framework
+for the C<MyApp> application (make sure you aren't still inside the
+directory of the C<Hello> application from the previous chapter of the
+tutorial or in a directory that already has a "MyApp" subdirectory):
$ catalyst.pl MyApp
created "MyApp"
created "MyApp/script/myapp_create.pl"
$ cd MyApp
-This creates a similar skeletal structure to what we saw in Part 2 of
-the tutorial, except with C<MyApp> and C<myapp> substituted for
+This creates a similar skeletal structure to what we saw in Chapter 2 of
+the tutorial, except with C<MyApp> and C<myapp> substituted for
C<Hello> and C<hello>.
=head1 EDIT THE LIST OF CATALYST PLUGINS
One of the greatest benefits of Catalyst is that it has such a large
-library of plugins available. Plugins are used to seamlessly integrate
-existing Perl modules into the overall Catalyst framework. In general,
-they do this by adding additional methods to the C<context> object
-(generally written as C<$c>) that Catalyst passes to every component
-throughout the framework.
+library of plugins and base classes available. Plugins are used to
+seamlessly integrate existing Perl modules into the overall Catalyst
+framework. In general, they do this by adding additional methods to the
+C<context> object (generally written as C<$c>) that Catalyst passes to
+every component throughout the framework.
By default, Catalyst enables three plugins/flags:
=over 4
-=item *
+=item *
C<-Debug> Flag
C<script/myapp_server.pl> development server earlier. You can remove
this item when you place your application into production.
-As you may have noticed, C<-Debug> is not a plugin, but a I<flag>.
-Although most of the items specified on the C<use Catalyst> line of your
-application class will be plugins, Catalyst supports a limited number of
-flag options (of these, C<-Debug> is the most common). See the
-documentation for C<Catalyst.pm> to get details on other flags
-(currently C<-Engine>, C<-Home>, and C<-Log>).
+As you may have noticed, C<-Debug> is not a plugin, but a I<flag>.
+Although most of the items specified on the C<__PACKAGE__-E<gt>setup>
+line of your application class will be plugins, Catalyst supports a
+limited number of flag options (of these, C<-Debug> is the most
+common). See the documentation for C<Catalyst.pm> to get details on
+other flags (currently C<-Engine>, C<-Home>, and C<-Log>).
If you prefer, you can use the C<$c-E<gt>debug> method to enable debug
messages.
B<TIP>: Depending on your needs, it can be helpful to permanently
remove C<-Debug> from C<lib/MyApp.pm> and then use the C<-d> option
to C<script/myapp_server.pl> to re-enable it just for the development
-server. We will not be using that approach in the tutorial, but feel
+server. We will not be using that approach in the tutorial, but feel
free to make use of it in your own projects.
=item *
hard-coded inside your Perl modules). Config::General uses syntax
very similar to Apache configuration files. We will see how to use
this feature of Catalyst during the authentication and authorization
-sections (Part 5 and Part 6).
-
-B<IMPORTANT NOTE:> If you are following along in Ubuntu 8.04 or
-otherwise using a version of L<Catalyst::Devel|Catalyst::Devel> prior
-to version 1.06, you need to be aware that Catalyst changed from a
-default format of YAML to the more straightforward C<Config::General>
-format. Because Catalyst has long supported both formats, this
-tutorial will simply use a configuration file called C<myapp.conf>
-instead of C<myapp.yml> and Catalyst will automatically use the new
-format. Just be aware that earlier versions of Catalyst will still
-create the C<myapp.yml> file and that you will need to B<remove
-C<myapp.yml>> and create a new C<myapp.conf> file by hand, but
-otherwise this transition is very painless. The default contents of
-C<myapp.conf> should only consist of one line: C<name MyApp>. Also be
-aware that you can continue to use any format supported by
-L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and
-L<Config::Any|Config::Any>, including YAML -- Catalyst will
-automatically look for any of the supported configuration file
-formats.
-
-B<TIP>: This script can be useful for converting between configuration
+sections (Chapter 5 and Chapter 6).
+
+B<IMPORTANT NOTE:> If you are using a version of
+L<Catalyst::Devel|Catalyst::Devel> prior to version 1.06, be aware
+that Catalyst changed the default format from YAML to the more
+straightforward C<Config::General> style. This tutorial uses the
+newer C<myapp.conf> file for C<Config::General>. However, Catalyst
+supports both formats and will automatically use either C<myapp.conf>
+or C<myapp.yml> (or any other format supported by
+L<Catalyst::Plugin::ConfigLoader|Catalyst::Plugin::ConfigLoader> and
+L<Config::Any|Config::Any>). If you are using a version of
+Catalyst::Devel prior to 1.06, you can convert to the newer format by
+simply creating the C<myapp.conf> file manually and deleting
+C<myapp.yml>. The default contents of the C<myapp.conf> you create
+should only consist of one line:
+
+ name MyApp
+
+B<TIP>: This script can be useful for converting between configuration
formats:
- perl -Ilib -e 'use MyApp; use Config::General;
+ perl -Ilib -e 'use MyApp; use Config::General;
Config::General->new->save_file("myapp.conf", MyApp->config);'
-B<NOTE:> The default C<myapp.conf> should look like:
-
- name MyApp
-
=item *
L<Catalyst::Plugin::Static::Simple|Catalyst::Plugin::Static::Simple>
=back
-To modify the list of plugins, edit C<lib/MyApp.pm> (this file is
-generally referred to as your I<application class>) and delete the line
-with:
+For our application, we want to add one new plugin into the mix. To
+do this, edit C<lib/MyApp.pm> (this file is generally referred to as
+your I<application class>) and delete the lines with:
+
+ use Catalyst qw/-Debug
+ ConfigLoader
+ Static::Simple/;
- use Catalyst qw/-Debug ConfigLoader Static::Simple/;
+Then replace it with:
-Replace it with:
+ # Load plugins
+ use Catalyst qw/-Debug
+ ConfigLoader
+ Static::Simple
+
+ StackTrace
+ /;
- use Catalyst qw/
- -Debug
- ConfigLoader
- Static::Simple
+B<Note:> Recent versions of C<Catalyst::Devel> have used a variety of
+techniques to load these plugins/flags. For example, you might see
+the following:
- StackTrace
- /;
+ __PACKAGE__->setup(qw/-Debug ConfigLoader Static::Simple/);
-This tells Catalyst to start using one new plugin:
+Don't let these variations confuse you -- they all accomplish the same
+result.
+
+This tells Catalyst to start using one new plugin,
+L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>, to add a
+stack trace to the standard Catalyst "debug screen" (the screen
+Catalyst sends to your browser when an error occurs). Be aware that
+L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
+browser, not in the console window from which you're running your
+application, which is where logging output usually goes.
+
+B<Notes:>
=over 4
-=item *
+=item *
-L<Catalyst::Plugin::StackTrace|Catalyst::Plugin::StackTrace>
+C<__PACKAGE__> is just a shorthand way of referencing the name of the
+package where it is used. Therefore, in C<MyApp.pm>, C<__PACKAGE__>
+is equivalent to C<MyApp>.
-Adds a stack trace to the standard Catalyst "debug screen" (this is the
-screen Catalyst sends to your browser when an error occurs).
+=item *
-Note: L<StackTrace|Catalyst::Plugin::StackTrace> output appears in your
-browser, not in the console window from which you're running your
-application, which is where logging output usually goes.
+You will want to disable L<StackTrace|Catalyst::Plugin::StackTrace>
+before you put your application into production, but it can be helpful
+during development.
-B<Note:> You will want to disable
-L<StackTrace|Catalyst::Plugin::StackTrace> before you put your
-application into production, but it can be helpful during development.
+=item *
-=back
+When specifying plugins on the C<__PACKAGE__-E<gt>setup> line, you can
+omit C<Catalyst::Plugin::> from the name. Additionally, you can
+spread the plugin names across multiple lines as shown here, or place
+them all on one (or more) lines as with the default configuration.
-Note that when specifying plugins on the C<use Catalyst> line, you can
-omit C<Catalyst::Plugin::> from the name. Additionally, you can spread
-the plugin names across multiple lines as shown here, or place them all
-on one (or more) lines as with the default configuration.
+=back
=head1 CREATE A CATALYST CONTROLLER
-As discussed earlier, controllers are where you write methods that
-interact with user input. Typically, controller methods respond to
+As discussed earlier, controllers are where you write methods that
+interact with user input. Typically, controller methods respond to
C<GET> and C<POST> messages from the user's web browser.
Use the Catalyst C<create> script to add a controller for book-related
created "/home/me/MyApp/script/../lib/MyApp/Controller/Books.pm"
created "/home/me/MyApp/script/../t/controller_Books.t"
-Then edit C<lib/MyApp/Controller/Books.pm> and add the following method
-to the controller:
+Then edit C<lib/MyApp/Controller/Books.pm> (as discussed in Chapter 2 of
+the Tutorial, Catalyst has a separate directory under C<lib/MyApp> for
+each of the three parts of MVC: C<Model>, C<View>, and C<Controller>)
+and add the following method to the controller:
=head2 list
Fetch all book objects and pass to books/list.tt2 in stash to be displayed
=cut
-
+
sub list : Local {
# Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
# 'Context' that's used to 'glue together' the various components
# Retrieve all of the book records as book model objects and store in the
# stash where they can be accessed by the TT template
- $c->stash->{books} = [$c->model('DB::Books')->all];
-
+ # $c->stash->{books} = [$c->model('DB::Books')->all];
+ # But, for now, use this code until we create the model later
+ $c->stash->{books} = '';
+
# Set the TT template to use. You will almost always want to do this
# in your action methods (action methods respond to user input in
# your controllers).
$c->stash->{template} = 'books/list.tt2';
}
-B<Note:> This won't actually work yet since you haven't set up your
-model yet. We will be covering the model soon.
-
-B<Note:> Programmers experienced with object-oriented Perl should
-recognize C<$self> as a reference to the object where this method was
-called. On the other hand, C<$c> will be new to many Perl programmers
-who have not used Catalyst before (it's sometimes written as
-C<$context>). The Context object is automatically passed to all
-Catalyst components. It is used to pass information between
-components and provide access to Catalyst and plugin functionality.
-
-B<TIP>: You may see the C<$c-E<gt>model('DB::Book')> used above
-written as C<$c-E<gt>model('DB')-E<gt>resultset('Book')>. The two
-are equivalent.
-
-B<Note:> Catalyst actions are regular Perl methods, but they make use
-of Nicholas Clark's C<attributes> module (that's the C<: Local> next
-to the C<sub list> in the code above) to provide additional
-information to the Catalyst dispatcher logic. Many newer Catalyst
-applications are switching to the use of "Literal" C<:Path> actions
-and C<Args> attribute in lieu of C<: Local> and C<: Private>. For
-example, C<sub any_method :Path :Args(0)> can be used instead of
-C<sub index :Private> (because no path was supplied to C<Path> it
-matches the "empty" URL in the namespace of that module... the same
-thing C<sub index> would do) or C<sub list :Path('list') :Args(0)>
-could be used instead of the C<sub list : Local> above (the C<list>
-argument to C<Path> would make it match on the URL C<list> under
-C<books>, the namespace of the current module). See "Action Types" in
-L<Catalyst::Manual::Intro|Catalyst::Manual::Intro> as well as Part 5
-of this tutorial (Authentication) for additional information. Another
-popular but more advanced feature is C<Chained> actions that allow a
-single URL to "chain together" multiple action method calls, each with
-an appropriate number of arguments (see
-L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained>
-for details).
+B<TIP>: See Appendix 1 for tips on removing the leading spaces when
+cutting and pasting example code from POD-based documents.
+
+Programmers experienced with object-oriented Perl should recognize
+C<$self> as a reference to the object where this method was called.
+On the other hand, C<$c> will be new to many Perl programmers who have
+not used Catalyst before (it's sometimes written as C<$context>). The
+Context object is automatically passed to all Catalyst components. It
+is used to pass information between components and provide access to
+Catalyst and plugin functionality.
+
+Catalyst actions are regular Perl methods, but they make use of
+attributes (the "C<: Local>" next to the "C<sub list>" in the code
+above) to provide additional information to the Catalyst dispatcher
+logic (note that the space between the colon and the attribute name is
+optional... you will see attributes written both ways). Most Catalyst
+Controllers use one of five action types:
+
+=over 4
+
+=item *
+
+B<:Private> -- Use C<:Private> for methods that you want to make into
+an action, but you do not want Catalyst to directly expose the action
+to your users. Catalyst will not map C<:Private> methods to a URI.
+Use them for various sorts of "special" methods (the C<begin>,
+C<auto>, etc. discussed below) or for methods you want to be able to
+C<forward> or C<detach> to. (If the method is a plain old "helper
+method" that you don't want to be an action at all, then just define
+the method without any attribute -- you can call it in your code, but
+the Catalyst dispatcher will ignore it.)
+
+There are five types of "special" build-in C<:Private> actions:
+C<begin>, C<end>, C<default>, C<index>, and C<auto>.
+
+=over 4
+
+=item *
+
+With C<begin>, C<end>, C<default>, C<index> private actions, only the
+most specific action of each type will be called. For example, if you
+define a C<begin> action in your controller it will I<override> a
+C<begin> action in your application/root controller -- I<only> the
+action in your controller will be called.
+
+=item *
+
+Unlike the other actions where only a single method is called for each
+request, I<every> auto action along the chain of namespaces will be
+called. Each C<auto> action will be called I<from the application/root
+controller down through the most specific class>.
+
+=back
+
+=item *
+
+B<:Path> -- C<:Path> actions let you map a method to an explicit URI
+path. For example, "C<:Path('list')>" in
+C<lib/MyApp/Controller/Books.pm> would match on the URL
+C<http://localhost:3000/books/list> but "C<:Path('/list')>" would match
+on C<http://localhost:3000/list>. You can use C<:Args()> to specify
+how many arguments an action should except. See
+L<Catalyst::Manual::Intro/Action_types> for more information and a few
+examples.
+
+=item *
+
+B<:Local> -- C<:Local> is merely a shorthand for
+"C<:Path('_name_of_method_')>". For example, these are equivalent:
+"C<sub create_book :Local {...}>" and
+"C<sub create_book :Path('create_book') {...}>".
+
+=item *
+
+B<:Global> -- C<:Global> is merely a shorthand for
+"C<:Path('/_name_of_method_')>". For example, these are equivalent:
+"C<sub create_book :Global {...}>" and
+"C<sub create_book :Path('/create_book') {...}>".
+
+=item *
+
+B<:Chained> -- Newer Catalyst applications tend to use the Chained
+dispatch form of action types because of its power and flexibility.
+It allows a series of controller methods to automatically be dispatched
+to service a single user request. See
+L<Catalyst::Manual::Tutorial::BasicCRUD|Catalyst::Manual::Tutorial::BasicCRUD>
+and L<Catalyst::DispatchType::Chained|Catalyst::DispatchType::Chained>
+for more information on chained actions.
+
+=back
+
+You should refer to L<Catalyst::Manual::Intro/Action_types> for
+additional information and for coverage of some lesser-used action
+types not discussed here (C<Regex> and C<LocalRegex>).
=head1 CATALYST VIEWS
-As mentioned in Part 2 of the tutorial, views are where you render
-output, typically for display in the user's web browser, but also
-possibly using other display output- generation systems. As with
-virtually every aspect of Catalyst, options abound when it comes to
-the specific view technology you adopt inside your application.
-However, most Catalyst applications use the Template Toolkit, known as
-TT (for more information on TT, see
-L<http://www.template-toolkit.org>). Other popular view technologies
-include Mason (L<http://www.masonhq.com> and
-L<http://www.masonbook.com>) and L<HTML::Template>
-(L<http://html-template.sourceforge.net>).
+As mentioned in Chapter 2 of the tutorial, views are where you render
+output, typically for display in the user's web browser (but also
+possibly using other display output-generation systems). The code in
+C<lib/MyApp/View> selects the I<type> of view to use, with the actual
+rendering template found in the C<root> directory. As with virtually
+every aspect of Catalyst, options abound when it comes to the specific
+view technology you adopt inside your application. However, most
+Catalyst applications use the Template Toolkit, known as TT (for more
+information on TT, see L<http://www.template-toolkit.org>). Other
+somewhat popular view technologies include Mason
+(L<http://www.masonhq.com> and L<http://www.masonbook.com>) and
+L<HTML::Template> (L<http://html-template.sourceforge.net>).
+
-=head2 Create a Catalyst View Using C<TTSite>
+=head2 Create a Catalyst View
When using TT for the Catalyst view, there are two main helper scripts:
=back
-Both are similar, but C<TT> merely creates the C<lib/MyApp/View/TT.pm>
+Both helpers are similar. C<TT> creates the C<lib/MyApp/View/TT.pm>
file and leaves the creation of any hierarchical template organization
entirely up to you. (It also creates a C<t/view_TT.t> file for testing;
-test cases will be discussed in Part 8). The C<TTSite> helper creates a
-modular and hierarchical view layout with separate Template Toolkit (TT)
-files for common header and footer information, configuration values, a
-CSS stylesheet, and more.
-
-While TTSite is useful to bootstrap a project, we recommend that
-unless you know what you're doing or want to pretty much use the
-supplied templates as is, that you use the plain Template Toolkit view
-when starting a project from scratch. This is because TTSite can be
-tricky to customize. Additionally TT contains constructs that you
-need to learn yourself if you're going to be a serious user of TT.
-Our experience suggests that you're better off learning these from
-scratch. We use TTSite here precisely because it is useful for
-bootstrap/prototype purposes.
-
-Enter the following command to enable the C<TTSite> style of view
+test cases will be discussed in Chapter 8.) C<TTSite>, on the other hand,
+creates a modular and hierarchical view layout with
+separate Template Toolkit (TT) files for common header and footer
+information, configuration values, a CSS stylesheet, and more.
+
+While C<TTSite> was useful to bootstrap a project, its use is now
+deprecated and to be considered historical. For most Catalyst
+applications it adds redundant functionality and structure; many in the
+Catalyst community recommend that it's easier to learn both Catalyst and
+Template Toolkit if you use the more basic C<TT> approach.
+Consequently, this tutorial will use "plain old TT."
+
+Enter the following command to enable the C<TT> style of view
rendering for this tutorial:
- $ script/myapp_create.pl view TT TTSite
+ $ script/myapp_create.pl view TT TT
exists "/home/me/MyApp/script/../lib/MyApp/View"
exists "/home/me/MyApp/script/../t"
- created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm"
- created "/home/me/MyApp/script/../root/lib"
- ...
- created "/home/me/MyApp/script/../root/src/ttsite.css"
-
-This puts a number of files in the C<root/lib> and C<root/src>
-directories that can be used to customize the look and feel of your
-application. Also take a look at C<lib/MyApp/View/TT.pm> for config
-values set by the C<TTSite> helper.
-
-B<TIP>: When troubleshooting TT it can be helpful to enable variable
-C<DEBUG> options. You can do this in a Catalyst environment by adding
-a C<DEBUG> line to the C<__PACKAGE__->config> declaration in
-C<lib/MyApp/View/TT.pm>:
-
- __PACKAGE__->config({
- ...
- DEBUG => 'undef',
- ...
- });
-
-B<Note:> C<__PACKAGE__> is just a shorthand way of referencing the name
-of the package where it is used. Therefore, in C<TT.pm>,
-C<__PACKAGE__> is equivalent to C<TT>.
-
-There are a variety of options you can use, such as 'undef', 'all',
-'service', 'context', 'parser' and 'provider'. See
-L<Template::Constants> for more information (remove the C<DEBUG_>
-portion of the name shown in the TT docs and convert to lower case
-for use inside Catalyst).
-
-B<NOTE:> B<Please be sure to disable TT debug options before
-continuing the tutorial> (especially the 'undef' option -- leaving
-this enabled will conflict with several of the conventions used
-by this tutorial and TTSite to leave some variables undefined
-on purpose).
-
-
-=head2 Globally Customize Every View
-
-When using TTSite, files in the subdirectories of C<root/lib> can be
-used to make changes that will appear in every view. For example, to
-display optional status and error messages in every view, edit
-C<root/lib/site/layout>, updating it to match the following (the two HTML
-C<span> elements are new):
-
- <div id="header">[% PROCESS site/header %]</div>
-
- <div id="content">
- <span class="message">[% status_msg %]</span>
- <span class="error">[% error_msg %]</span>
- [% content %]
- </div>
-
- <div id="footer">[% PROCESS site/footer %]</div>
+ created "/home/me/MyApp/script/../lib/MyApp/View/TT.pm"
+ created "/home/me/MyApp/script/../t/view_TT.t"
-If we set either message in the Catalyst stash (e.g.,
-C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it will
-be displayed whenever any view used by that request is rendered. The
-C<message> and C<error> CSS styles are automatically defined in
-C<root/src/ttsite.css> and can be customized to suit your needs.
+This simply creates a view called C<TT> (the second 'TT' argument) in
+a file called C<TT.pm> (the first 'TT' argument). It is now up to you
+to decide how you want to structure your view layout. For the
+tutorial, we will start with a very simple TT template to initially
+demonstrate the concepts, but quickly migrate to a more typical
+"wrapper page" type of configuration (where the "wrapper" controls the
+overall "look and feel" of your site from a single file or set of
+files).
-B<Note:> The Catalyst stash only lasts for a single HTTP request. If
-you need to retain information across requests you can use
-L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
-Catalyst sessions in the Authentication part of the tutorial).
+Edit C<lib/MyApp/View/TT.pm> and you should see that the default
+contents contains something similar to the following:
+ __PACKAGE__->config(TEMPLATE_EXTENSION => '.tt');
-=head2 Create a TT Template Page
+And update it to match:
+
+ __PACKAGE__->config(
+ # Change default TT extension
+ TEMPLATE_EXTENSION => '.tt2',
+ # Set the location for TT files
+ INCLUDE_PATH => [
+ MyApp->path_to( 'root', 'src' ),
+ ],
+ );
+
+B<NOTE:> Make sure to add a comma after '.tt2' outside the single
+quote.
+
+This changes the default extension for Template Toolkit from '.tt' to
+'.tt2' and changes the base directory for your template files from
+C<root> to C<root/src>. These changes from the default are done mostly
+to facilitate the application we're developing in this tutorial; as with
+most things Perl, there's more than one way to do it...
-To add a new page of content to the TTSite view hierarchy, just create a
-new C<.tt2> file in C<root/src>. Only include HTML markup that goes
-inside the HTML <body> and </body> tags, TTSite will use the contents of
-C<root/lib/site> to add the top and bottom.
+B<Note:> We will use C<root/src> as the base directory for our
+template files, which a full naming convention of
+C<root/src/_controller_name_/_action_name_.tt2>. Another popular option is to
+use C<root/> as the base (with a full filename pattern of
+C<root/_controller_name_/_action_name_.tt2>).
+
+
+=head2 Create a TT Template Page
First create a directory for book-related TT templates:
- $ mkdir root/src/books
+ $ mkdir -p root/src/books
Then create C<root/src/books/list.tt2> in your editor and enter:
[% # it WILL eliminate a blank line if you view the HTML source. It's purely -%]
[%- # optional, but both the beginning and the ending TT tags support chomping. -%]
- [% # Provide a title to root/lib/site/header -%]
+ [% # Provide a title -%]
[% META title = 'Book List' -%]
<table>
</table>
As indicated by the inline comments above, the C<META title> line uses
-TT's META feature to provide a title to C<root/lib/site/header>.
-Meanwhile, the C<FOREACH> loop iterates through each C<book> model
-object and prints the C<title> and C<rating> fields.
+TT's META feature to provide a title to the "wrapper" that we will
+create later. Meanwhile, the C<FOREACH> loop iterates through each
+C<book> model object and prints the C<title> and C<rating> fields.
If you are new to TT, the C<[%> and C<%]> tags are used to delimit TT
code. TT supports a wide variety of directives for "calling" other
Pod documentation, you can access the TT manual at
L<http://search.cpan.org/perldoc?Template::Manual>.
-B<NOTE:> The C<TTSite> helper creates several TT files using an
-extension of C<.tt2>. Most other Catalyst and TT examples use an
-extension of C<.tt>. You can use either extension (or no extension at
-all) with TTSite and TT, just be sure to use the appropriate extension
-for both the file itself I<and> the C<$c-E<gt>stash-E<gt>{template} =
-...> line in your controller. This document will use C<.tt2> for
-consistency with the files already created by the C<TTSite> helper.
+B<TIP:> While you can build all sorts of complex logic into your TT
+templates, you should in general keep the "code" part of your templates
+as simple as possible. If you need more complex logic, create helper
+methods in your model that abstract out a set of code into a single call
+from your TT template. (Note that the same is true of your controller
+logic as well -- complex sections of code in your controllers should
+often be pulled out and placed into your model objects.)
+
+
+=head2 Test Run The Application
+
+To test your work so far, first start the development server:
+
+ $ script/myapp_server.pl
+
+Then point your browser to L<http://localhost:3000> and you should
+still get the Catalyst welcome page. Next, change the URL in your
+browser to L<http://localhost:3000/books/list>. If you have
+everything working so far, you should see a web page that displays
+nothing other than our column headers for "Title", "Rating", and
+"Author(s)" -- we will not see any books until we get the database and
+model working below.
+
+If you run into problems getting your application to run correctly, it
+might be helpful to refer to some of the debugging techniques covered in
+the L<Debugging|Catalyst::Manual::Tutorial::Debugging> part of the
+tutorial.
=head1 CREATE A SQLITE DATABASE
In this step, we make a text file with the required SQL commands to
-create a database table and load some sample data. Open C<myapp01.sql>
-in your editor and enter:
+create a database table and load some sample data. We will use SQLite,
+a popular database that is lightweight and easy to use. Open
+C<myapp01.sql> in your editor and enter:
--
-- Create a very simple database to hold book and author information
INSERT INTO book_authors VALUES (4, 7);
INSERT INTO book_authors VALUES (5, 8);
-B<TIP>: See Appendix 1 for tips on removing the leading spaces when
-cutting and pasting example code from POD-based documents.
-
Then use the following command to build a C<myapp.db> SQLite database:
$ sqlite3 myapp.db < myapp01.sql
If you need to create the database more than once, you probably want to
issue the C<rm myapp.db> command to delete the database before you use
-the C<sqlite3 myapp.db < myapp01.sql> command.
+the C<sqlite3 myapp.db E<lt> myapp01.sql> command.
Once the C<myapp.db> database file has been created and initialized, you
can use the SQLite command line environment to do a quick dump of the
database contents:
$ sqlite3 myapp.db
- SQLite version 3.4.2
+ SQLite version 3.5.9
Enter ".help" for instructions
sqlite> select * from books;
1|CCSP SNRS Exam Certification Guide|5
".q" to exit from SQLite from the SQLite interactive mode and return to
your OS command prompt.
+For using other databases, such as PostgreSQL or MySQL, see
+L<Appendix 2|Catalyst::Manual::Tutorial::Appendices>.
+
=head1 DATABASE ACCESS WITH C<DBIx::Class>
-Catalyst can be used with virtually any form of persistent datastore
+Catalyst can be used with virtually any form of persistent datastore
available via Perl. For example,
-L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to
-easily access databases through the traditional Perl C<DBI> interface.
-However, most Catalyst applications use some form of ORM technology to
-automatically create and save model objects as they are used. Although
-Tony Bowden's L<Class::DBI|Class::DBI> has been a popular choice
-in the past, Matt Trout's L<DBIx::Class|DBIx::Class> (abbreviated
-as "DBIC") has rapidly emerged as the Perl-based ORM technology of choice.
-Most new Catalyst applications rely on DBIC, as will this tutorial.
-
-=head2 Create a dynamic DBIC Model
-
-Use the C<create=dynamic> model helper option to build a model that
+L<Catalyst::Model::DBI|Catalyst::Model::DBI> can be used to easily
+access databases through the traditional Perl C<DBI> interface. However,
+most Catalyst applications use some form of ORM technology to
+automatically create and save model objects as they are used. Although
+L<Class::DBI|Class::DBI> has been a popular choice in the past, Matt
+Trout's L<DBIx::Class|DBIx::Class> (abbreviated as "DBIC") has rapidly
+emerged as the Perl-based ORM technology of choice. Most new Catalyst
+applications rely on DBIC, as will this tutorial.
+
+
+=head2 Create a Dynamic DBIC Model
+
+Use the C<create=dynamic> model helper option to build a model that
dynamically reads your database structure every time the application
starts:
- $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=dynamic dbi:SQLite:myapp.db
- exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model"
- exists "/home/kclark/dev/MyApp/script/../t"
- exists "/home/kclark/dev/MyApp/script/../lib/MyApp"
- created "/home/kclark/dev/MyApp/script/../lib/MyApp/Schema.pm"
- created "/home/kclark/dev/MyApp/script/../lib/MyApp/Model/DB.pm"
- created "/home/kclark/dev/MyApp/script/../t/model_DB.t"
+ $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
+ create=dynamic dbi:SQLite:myapp.db
+ exists "/home/me/MyApp/script/../lib/MyApp/Model"
+ exists "/home/me/MyApp/script/../t"
+ exists "/home/me/MyApp/script/../lib/MyApp"
+ created "/home/me/MyApp/script/../lib/MyApp/Schema.pm"
+ created "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
+ created "/home/me/MyApp/script/../t/model_DB.t"
+
+
+The C<script/myapp_create.pl> command breaks down like this:
+
+=over 4
+=item *
C<DB> is the name of the model class to be created by the helper in
-C<lib/MyApp/Model> (Catalyst has a separate directory under C<lib/MyApp>
-for each of the three parts of MVC: C<Model>, C<View>, and C<Controller>).
-C<DBIC::Schema> is the type of the model to create.
-C<MyApp::Schema> is the name of the DBIC schema file written to
-C<lib/MyApp/Schema.pm>. Because we specified C<create=dynamic>
-to the helper, it use L<DBIx::Class::Schema::Loader> to dynamically load
-the schema information from the database every time the application
-starts. And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect
-string for use with SQLite.
+C<lib/MyApp/Model>.
+
+=item *
+
+C<DBIC::Schema> is the type of the model to create.
+
+=item *
+
+C<MyApp::Schema> is the name of the DBIC schema file written to
+C<lib/MyApp/Schema.pm>.
+
+=item *
+
+Because we specified C<create=dynamic> to the helper, it use
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> to
+dynamically load the schema information from the database every time
+the application starts.
+
+=item *
+
+And finally, C<dbi:SQLite:myapp.db> is the standard DBI connect string
+for use with SQLite.
+
+=back
B<NOTE:> Although the C<create=dynamic> option to the DBIC helper
makes for a nifty demonstration, is only really suitable for very
use the C<create=static> option that we switch to below.
-=head1 RUN THE APPLICATION
+=head1 ENABLE THE MODEL IN THE CONTROLLER
+
+Open C<lib/MyApp/Controller/Books.pm> and un-comment the model code we
+left disabled earlier so that your version matches the following (un-
+comment the line containing C<[$c-E<gt>model('DB::Books')-E<gt>all]>
+and delete the next 2 lines):
+
+ =head2 list
+
+ Fetch all book objects and pass to books/list.tt2 in stash to be displayed
+
+ =cut
+
+ sub list : Local {
+ # Retrieve the usual Perl OO '$self' for this object. $c is the Catalyst
+ # 'Context' that's used to 'glue together' the various components
+ # that make up the application
+ my ($self, $c) = @_;
+
+ # Retrieve all of the book records as book model objects and store in the
+ # stash where they can be accessed by the TT template
+ $c->stash->{books} = [$c->model('DB::Books')->all];
+
+ # Set the TT template to use. You will almost always want to do this
+ # in your action methods (action methods respond to user input in
+ # your controllers).
+ $c->stash->{template} = 'books/list.tt2';
+ }
+
+B<TIP>: You may see the C<$c-E<gt>model('DB::Books')> un-commented
+above written as C<$c-E<gt>model('DB')-E<gt>resultset('Books')>. The
+two are equivalent. Either way, C<$c-E<gt>model> returns a
+L<DBIx::Class::ResultSet|DBIx::Class::ResultSet> which handles queries
+against the database and iterating over the set of results that are
+returned.
+
+We are using the C<-E<gt>all> to fetch all of the books. DBIC
+supports a wide variety of more advanced operations to easily do
+things like filtering and sorting the results. For example, the
+following could be used to sort the results by descending title:
+
+ $c->model('DB::Books')->search({}, {order_by => 'title DESC'});
+
+Some other examples are provided in
+L<DBIx::Class::Manual::Cookbook/Complex WHERE clauses>, with
+additional information found at L<DBIx::Class::ResultSet/search>,
+L<DBIx::Class::Manual::FAQ/Searching>,
+L<DBIx::Class::Manual::Intro|DBIx::Class::Manual::Intro>
+and L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>.
+
-First, let's enable an environment variable option that causes
-DBIx::Class to dump the SQL statements it's using to access the database
-(this option can provide extremely helpful troubleshooting information):
+=head2 Test Run The Application
+
+First, let's enable an environment variable that causes DBIx::Class to
+dump the SQL statements used to access the database. This is a
+helpful trick when you are trying to debug your database-oriented
+code:
$ export DBIC_TRACE=1
to log to file instead of displaying to the Catalyst development server
log).
-Then run the Catalyst "demo server" script:
+Then launch the Catalyst development server. The log output should
+display something like:
$ script/myapp_server.pl
-
-Your development server log output should display something like:
-
- $script/myapp_server.pl
[debug] Debug messages enabled
+ [debug] Statistics enabled
[debug] Loaded plugins:
.----------------------------------------------------------------------------.
- | Catalyst::Plugin::ConfigLoader 0.17 |
- | Catalyst::Plugin::StackTrace 0.06 |
+ | Catalyst::Plugin::ConfigLoader 0.20 |
+ | Catalyst::Plugin::StackTrace 0.08 |
| Catalyst::Plugin::Static::Simple 0.20 |
'----------------------------------------------------------------------------'
+----------------------+--------------------------------------+--------------+
| /default | MyApp::Controller::Root | default |
| /end | MyApp::Controller::Root | end |
+ | /index | MyApp::Controller::Root | index |
| /books/index | MyApp::Controller::Books | index |
| /books/list | MyApp::Controller::Books | list |
'----------------------+--------------------------------------+--------------'
.-------------------------------------+--------------------------------------.
| Path | Private |
+-------------------------------------+--------------------------------------+
+ | / | /default |
+ | / | /index |
+ | /books | /books/index |
| /books/list | /books/list |
'-------------------------------------+--------------------------------------'
- [info] MyApp powered by Catalyst 5.7011
- You can connect to your server at http://localhost:3000
-
-B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from
-the 'base' directory of your application, not inside the C<script>
-directory itself or it will not be able to locate the C<myapp.db>
-database file. You can use a fully qualified or a relative path to
-locate the database file, but we did not specify that when we ran the
+ [info] MyApp powered by Catalyst 5.71000
+ You can connect to your server at http://debian:3000
+
+B<NOTE:> Be sure you run the C<script/myapp_server.pl> command from
+the 'base' directory of your application, not inside the C<script>
+directory itself or it will not be able to locate the C<myapp.db>
+database file. You can use a fully qualified or a relative path to
+locate the database file, but we did not specify that when we ran the
model helper earlier.
Some things you should note in the output above:
=over 4
-=item *
+=item *
-Catalyst::Model::DBIC::Schema dynamically created three model classes,
-one to represent each of the three tables in our database
+Catalyst::Model::DBIC::Schema dynamically created three model classes,
+one to represent each of the three tables in our database
(C<MyApp::Model::DB::Authors>, C<MyApp::Model::DB::BookAuthors>,
and C<MyApp::Model::DB::Books>).
-=item *
+=item *
The "list" action in our Books controller showed up with a path of
C</books/list>.
Next, to view the book list, change the URL in your browser to
L<http://localhost:3000/books/list>. You should get a list of the five
-books loaded by the C<myapp01.sql> script above, with TTSite providing
-the formatting for the very simple output we generated in our template.
-The rating for each book should appear on each row.
+books loaded by the C<myapp01.sql> script above without any formatting.
+The rating for each book should appear on each row, but the "Author(s)"
+column will still be blank (we will fill that in later).
Also notice in the output of the C<script/myapp_server.pl> that DBIC
used the following SQL to retrieve the data:
more fully.
+=head1 CREATE A WRAPPER FOR THE VIEW
+
+When using TT, you can (and should) create a wrapper that will
+literally wrap content around each of your templates. This is
+certainly useful as you have one main source for changing things that
+will appear across your entire site/application instead of having to
+edit many individual files.
+
+
+=head2 Configure TT.pm For The Wrapper
+
+In order to create a wrapper, you must first edit your TT view and
+tell it where to find your wrapper file. Your TT view is located in
+C<lib/MyApp/View/TT.pm>.
+
+Edit C<lib/MyApp/View/TT.pm> and change it to match the following:
+
+ __PACKAGE__->config(
+ # Change default TT extension
+ TEMPLATE_EXTENSION => '.tt2',
+ # Set the location for TT files
+ INCLUDE_PATH => [
+ MyApp->path_to( 'root', 'src' ),
+ ],
+ # Set to 1 for detailed timer stats in your HTML as comments
+ TIMER => 0,
+ # This is your wrapper template located in the 'root/src'
+ WRAPPER => 'wrapper.tt2',
+ );
+
+
+=head2 Create the Wrapper Template File and Stylesheet
+
+Next you need to set up your wrapper template. Basically, you'll want
+to take the overall layout of your site and put it into this file.
+For the tutorial, open C<root/src/wrapper.tt2> and input the following:
+
+ <?xml version="1.0" encoding="UTF-8"?>
+ <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+ <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+ <head>
+ <title>[% template.title or "My Catalyst App!" %]</title>
+ <link rel="stylesheet" href="[% c.uri_for('/static/css/main.css') %]" />
+ </head>
+
+ <body>
+ <div id="outer">
+ <div id="header">
+ [%# Your logo could go here -%]
+ <img src="[% c.uri_for('/static/images/btn_88x31_powered.png') %]" />
+ [%# Insert the page title -%]
+ <h1>[% template.title or site.title %]</h1>
+ </div>
+
+ <div id="bodyblock">
+ <div id="menu">
+ Navigation:
+ <ul>
+ <li><a href="[% c.uri_for('/books/list') %]">Home</a></li>
+ <li><a href="[% c.uri_for('/') %]" title="Catalyst Welcome Page">Welcome</a></li>
+ </ul>
+ </div><!-- end menu -->
+
+ <div id="content">
+ [%# Status and error messages %]
+ <span class="message">[% status_msg %]</span>
+ <span class="error">[% error_msg %]</span>
+ [%# This is where TT will stick all of your template's contents. -%]
+ [% content %]
+ </div><!-- end content -->
+ </div><!-- end bodyblock -->
+
+ <div id="footer">Copyright (c) your name goes here</div>
+ </div><!-- end outer -->
+
+ </body>
+ </html>
+
+Notice the status and error message sections in the code above:
+
+ <span class="status">[% status_msg %]</span>
+ <span class="error">[% error_msg %]</span>
+
+If we set either message in the Catalyst stash (e.g.,
+C<$c-E<gt>stash-E<gt>{status_msg} = 'Request was successful!'>) it
+will be displayed whenever any view used by that request is rendered.
+The C<message> and C<error> CSS styles can be customized to suit your
+needs in the C<root/static/css/main.css> file we create below.
+
+B<Notes:>
+
+=over 4
+
+=item *
+
+The Catalyst stash only lasts for a single HTTP request. If
+you need to retain information across requests you can use
+L<Catalyst::Plugin::Session|Catalyst::Plugin::Session> (we will use
+Catalyst sessions in the Authentication chapter of the tutorial).
+
+=item *
+
+Although it is beyond the scope of this tutorial, you may wish to use
+a JavaScript or AJAX tool such as jQuery (L<http://www.jquery.com>) or
+Dojo (L<http://www.dojotoolkit.org>).
+
+=back
+
+
+=head3 Create A Basic Stylesheet
+
+First create a central location for stylesheets under the static
+directory:
+
+ $ mkdir root/static/css
+
+Then open the file C<root/static/css/main.css> (the file referenced in
+the stylesheet href link of our wrapper above) and add the following
+content:
+
+ #header {
+ text-align: center;
+ }
+ #header h1 {
+ margin: 0;
+ }
+ #header img {
+ float: right;
+ }
+ #footer {
+ text-align: center;
+ font-style: italic;
+ padding-top: 20px;
+ }
+ #menu {
+ font-weight: bold;
+ background-color: #ddd;
+ }
+ #menu ul {
+ list-style: none;
+ float: left;
+ margin: 0;
+ padding: 0 0 50% 5px;
+ font-weight: normal;
+ background-color: #ddd;
+ width: 100px;
+ }
+ #content {
+ margin-left: 120px;
+ }
+ .message {
+ color: #390;
+ }
+ .error {
+ color: #f00;
+ }
+
+You may wish to check out a "CSS Framework" like Emastic
+(L<http://code.google.com/p/emastic/>) as a way to quickly
+provide lots of high-quality CSS functionality.
+
+
+=head2 Test Run The Application
+
+Restart the development server and hit "Reload" in your web browser
+and you should now see a formatted version of our basic book list.
+Although our wrapper and stylesheet are obviously very simple, you
+should see how it allows us to control the overall look of an entire
+website from two central files. To add new pages to the site, just
+provide a template that fills in the C<content> section of our wrapper
+template -- the wrapper will provide the overall feel of the page.
+
+
=head1 A STATIC DATABASE MODEL WITH C<DBIx::Class>
+First, let's be sure we have a recent versino of the DBIC helper,
+L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema>, by
+running this command:
+
+ $ perl -MCatalyst::Model::DBIC::Schema -e \
+ 'print "$Catalyst::Model::DBIC::Schema::VERSION\n"'
+ 0.23
+
+If you don't have version 0.23 or higher, please run this command
+to install it directly from CPAN:
+
+ $ sudo cpan Catalyst::Model::DBIC::Schema
+
+And re-run the version print command to verify that you are now at
+0.23 or higher.
+
+
=head2 Create Static DBIC Schema Files
-Unlike the previous section where we had DBIC automatically discover the
-structure of the database every time the application started, here we
-will use static schema files for more control. This is typical of most
-"real world" applications.
+Unlike the previous DBIC section where we had C<create=dynamic>
+automatically discover the structure of the database every time the
+application started, here we will use static schema files for more
+control. This is typical of most "real world" applications.
-One option would be to create a separate schema file for each table in
-the database, however, lets use the same L<DBIx::Class::Schema::Loader>
-used earlier with C<create=dynamic> to build the static files for us.
+One option would be to manually create a separate schema file for each
+table in the database, however, lets use the same
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> used
+earlier with C<create=dynamic> to build the static files for us.
First, lets remove the schema file created earlier:
- $ rm lib/MyApp/Schema.pm
+ $ rm lib/MyApp/Schema.pm
Now regenerate the schema using the C<create=static> option:
- $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema create=static dbi:SQLite:myapp.db
- exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model"
- exists "/home/kclark/dev/MyApp/script/../t"
- Dumping manual schema for MyApp::Schema to directory /home/kclark/dev/MyApp/script/../lib ...
+ $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
+ create=static components=TimeStamp dbi:SQLite:myapp.db
+ exists "/home/me/MyApp/script/../lib/MyApp/Model"
+ exists "/home/me/MyApp/script/../t"
+ Dumping manual schema for MyApp::Schema to directory /home/me/MyApp/script/../lib ...
Schema dump completed.
- exists "/home/kclark/dev/MyApp/script/../lib/MyApp/Model/DB.pm"
+ exists "/home/me/MyApp/script/../lib/MyApp/Model/DB.pm"
-We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would
+We could have also deleted C<lib/MyApp/Model/DB.pm>, but it would
have regenerated the same file (note the C<exists> in the output above).
If you take a look at C<lib/MyApp/Model/DB.pm>, it simply contains
a reference to the actual schema file in C<lib/MyApp/Schema.pm>
along with the database connect string.
-If you look in the C<lib/MyApp/Schema> directory, you will find that
-C<DB.pm> is no longer using L<DBIx::Class::Schema::Loader> as its
-base class (L<DBIx::Class::Schema::Loader> is only being used by the
-helper to load the schema once and then create the static files for us)
-and that it only contains a call to the C<load_classes> method. You
-will also find that C<lib/MyApp/Schema> contains a C<Schema>
-subdirectory, with one file inside this directory for each of the tables
-in our simple database (C<Authors.pm>, C<BookAuthors.pm>, and
-C<Books.pm>). These three files were created based on the information
-found by L<DBIx::Class::Schema::Loader> as the helper ran.
-
-The idea with all of the files created under C<lib/MyApp/Schema> by the
-C<create=static> option is to only edit the files below the C<# DO NOT
-MODIFY THIS OR ANYTHING ABOVE!> warning. If you place all of your
-changes below that point in the file, you can regenerate the
-auto-generated information at the top of each file should your database
-structure get updated.
+If you look in the C<lib/MyApp/Schema.pm> file, you will find that it
+is no longer using
+L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> as its base
+class (L<DBIx::Class::Schema::Loader|DBIx::Class::Schema::Loader> is
+only being used by the helper to load the schema once and then create
+the static files for us) and C<Schema.pm> only contains a call to the
+C<load_namespaces> method. You will also find that C<lib/MyApp>
+contains a C<Schema> subdirectory, which then has a subdirectory
+called "Result". This "Result" subdirectory then has files named
+according to each of the tables in our simple database (C<Authors.pm>,
+C<BookAuthors.pm>, and C<Books.pm>). These three files are called
+"Result Classes" in DBIC nomenclature. Although the Result Class files
+are named after tables in our database, the classes correspond to the
+I<row-level data> that is returned by DBIC (more on this later,
+especially in
+L<Catalyst::Manual::Tutorial::BasicCRUD/EXPLORING THE POWER OF DBIC>.
+
+The idea with the Result Source files created under
+C<lib/MyApp/Schema/Result> by the C<create=static> option is to only
+edit the files below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!>
+warning. If you place all of your changes below that point in the
+file, you can regenerate the automatically created information at the
+top of each file should your database structure get updated.
Also note the "flow" of the model information across the various files
and directories. Catalyst will initially load the model from
-C<lib/MyApp/Model/DB.pm>. This file contains a reference to
-C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally,
-the call to C<load_classes> in that file will load each of the
-table-specific "results source" files from the C<lib/MyApp/Schema>
-subdirectory. These three table-specific DBIC schema files will then be
-used to create three table-specific Catalyst models every time the
-application starts (you can see these three model files listed in
-the debug output generated when you launch the application).
+C<lib/MyApp/Model/DB.pm>. This file contains a reference to
+C<lib/MyApp/Schema.pm>, so that file is loaded next. Finally, the
+call to C<load_namespaces> in C<Schema.pm> will load each of the
+"Result Class" files from the C<lib/MyApp/Schema/Result> subdirectory.
+The final outcome is that Catalyst will dynamically create three
+table-specific Catalyst models every time the application starts (you
+can see these three model files listed in the debug output generated
+when you launch the application).
+
+B<NOTE:> Older versions of
+L<Catalyst::Model::DBIC::Schema|Catalyst::Model::DBIC::Schema> use the
+deprecated DBIC C<load_classes> technique instead of the newer
+C<load_namspaces>. For new applications, please try to use
+C<load_namespaces> since it more easily supports a very useful DBIC
+technique called "ResultSet Classes." If you need to convert an
+existing application from "load_classes" to "load_namespaces," you can
+use this process to automate the migration (but first make sure you
+have v0.23 C<Catalyst::Model::DBIC::Schema> as discussed above):
+
+ $ # First delete the existing schema file to disable "compatibility" mode
+ $ rm lib/MyApp/Schema.pm
+ $
+ $ # Then re-run the helper to build the files for "load_namespaces"
+ $ script/myapp_create.pl model DB DBIC::Schema MyApp::Schema \
+ create=static components=TimeStamp dbi:SQLite:myapp.db
+ $
+ $ # Now convert the existing files over
+ $ cd lib/MyApp/Schema
+ $ perl -MIO::All -e 'for (@ARGV) { my $s < io($_); $s =~ s/.*\n\# You can replace.*?\n//s;
+ $s =~ s/'MyApp::Schema::/'MyApp::Schema::Result::/g; my $d < io("Result/$_");
+ $d =~ s/1;\n?//; "$d$s" > io("Result/$_"); }' *.pm
+ $ cd ../../..
+ $
+ $ # And finally delete the old files
+ $ rm lib/MyApp/Schema/*.pm
+The "C<perl -MIO::ALL ...>" script will copy all the customized
+relationship (and other) information below "C<# DO NOT MODIFY>" line
+from the old files in C<lib/MyApp/Schema> to the new files in
+C<lib/MyApp/Schema/Result> (we will be starting to add some
+"customized relationship information in the section below).
-=head2 Updating the Generated DBIC Schema Files
+=head2 Updating the Generated DBIC Result Class Files
-Let's manually add some relationship information to the auto-generated
-schema files. First edit C<lib/MyApp/Schema/Books.pm> and
-add the following text below the C<# You can replace this text...>
-comment:
+Let's manually add some relationship information to the auto-generated
+Result Class files. (Note: if you are using a database other than
+SQLite, such as PostgreSQL, then the relationship could have been
+automatically placed in the Result Class files. If so, you can skip
+this step.) First edit C<lib/MyApp/Schema/Result/Books.pm> and add the
+following text below the C<# You can replace this text...> comment:
#
# Set relationships:
- #
+ #
# has_many():
# args:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
- # 3) Column name in *foreign* table
- __PACKAGE__->has_many(book_authors => 'MyApp::Schema::BookAuthors', 'book_id');
+ # 3) Column name in *foreign* table (aka, foreign key in peer table)
+ __PACKAGE__->has_many(book_authors => 'MyApp::Schema::Result::BookAuthors', 'book_id');
# many_to_many():
# args:
# 1) Name of relationship, DBIC will create accessor with this name
- # 2) Name of has_many() relationship this many_to_many() is shortcut for
- # 3) Name of belongs_to() relationship in model class of has_many() above
+ # 2) Name of has_many() relationship this many_to_many() is shortcut for
+ # 3) Name of belongs_to() relationship in model class of has_many() above
# You must already have the has_many() defined to use a many_to_many().
__PACKAGE__->many_to_many(authors => 'book_authors', 'author');
a statement that evaluates to C<true>. This is customarily done with
C<1;> on a line by itself.
-This code defines both a C<has_many> and a C<many_to_many> relationship.
-The C<many_to_many> relationship is optional, but it makes it easier to
-map a book to its collection of authors. Without it, we would have to
-"walk" though the C<book_authors> table as in C<$book-E<gt>book_authors-
-E<gt>first-E<gt>author-E<gt>last_name> (we will see examples on how to
-use DBIC objects in your code soon, but note that because C<$book-
-E<gt>book_authors> can return multiple authors, we have to use C<first>
-to display a single author). C<many_to_many> allows us to use the
-shorter C<$book-E<gt>authors-E<gt>first-E<gt>last_name>. Note that you
-cannot define a C<many_to_many> relationship without also having the
-C<has_many> relationship in place.
-
-Then edit C<lib/MyApp/Schema/Authors.pm> and add relationship
+C<Important Note:> Although this tutorial uses plural names for both
+the names of the SQL tables and therefore the Result Classes (after
+all, C<Schema::Loader> automatically named the Result Classes from the
+names of the SQL tables it found), DBIC users prefer singular names
+for these items. B<Please try to use singular table and DBIC
+model/Result Class names in your applications.> This tutorial will
+migrate to singular names as soon as possible (patches welcomed).
+B<Note that while singular is preferred for the DBIC model, plural is
+perfectly acceptable for the names of the controller classes.> After
+all, the C<Books.pm> controller operates on multiple books.
+
+This code defines both a C<has_many> and a C<many_to_many> relationship.
+The C<many_to_many> relationship is optional, but it makes it easier to
+map a book to its collection of authors. Without it, we would have to
+"walk" though the C<book_authors> table as in
+C<$book-E<gt>book_authors-E<gt>first-E<gt>author-E<gt>last_name>
+(we will see examples on how to use DBIC objects in your code soon,
+but note that because C<$book-E<gt>book_authors> can return multiple
+authors, we have to use C<first> to display a single author).
+C<many_to_many> allows us to use the shorter
+C<$book-E<gt>authors-E<gt>first-E<gt>last_name>.
+Note that you cannot define a C<many_to_many> relationship without
+also having the C<has_many> relationship in place.
+
+Then edit C<lib/MyApp/Schema/Result/Authors.pm> and add relationship
information as follows (again, be careful to put in above the C<1;> but
below the C<# DO NOT MODIFY THIS OR ANYTHING ABOVE!> comment):
# args:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
- # 3) Column name in *foreign* table
- __PACKAGE__->has_many(book_author => 'MyApp::Schema::BookAuthors', 'author_id');
+ # 3) Column name in *foreign* table (aka, foreign key in peer table)
+ __PACKAGE__->has_many(book_author => 'MyApp::Schema::Result::BookAuthors', 'author_id');
# many_to_many():
# args:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of has_many() relationship this many_to_many() is shortcut for
- # 3) Name of belongs_to() relationship in model class of has_many() above
+ # 3) Name of belongs_to() relationship in model class of has_many() above
# You must already have the has_many() defined to use a many_to_many().
__PACKAGE__->many_to_many(books => 'book_author', 'book');
-Finally, do the same for the "join table,"
-C<lib/MyApp/Schema/BookAuthors.pm>:
+Finally, do the same for the "join table,"
+C<lib/MyApp/Schema/Result/BookAuthors.pm>:
#
# Set relationships:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *this* table
- __PACKAGE__->belongs_to(book => 'MyApp::Schema::Books', 'book_id');
+ __PACKAGE__->belongs_to(book => 'MyApp::Schema::Result::Books', 'book_id');
# belongs_to():
# args:
# 1) Name of relationship, DBIC will create accessor with this name
# 2) Name of the model class referenced by this relationship
# 3) Column name in *this* table
- __PACKAGE__->belongs_to(author => 'MyApp::Schema::Authors', 'author_id');
+ __PACKAGE__->belongs_to(author => 'MyApp::Schema::Result::Authors', 'author_id');
-=head1 RUN THE APPLICATION
+=head2 Run The Application
Run the Catalyst "demo server" script with the C<DBIC_TRACE> option
(it might still be enabled from earlier in the tutorial, but here
$ DBIC_TRACE=1 script/myapp_server.pl
-Make sure that the application loads correctly and that you see the
-three dynamically created model class (one for each of the
-table-specific schema classes we created).
+Make sure that the application loads correctly and that you see the
+three dynamically created model class (one for each of the
+Result Classes we created).
-Then hit the URL L<http://localhost:3000/books/list> and be sure that
-the book list is displayed.
+Then hit the URL L<http://localhost:3000/books/list> with your browser
+and be sure that the book list is displayed via the relationships
+established above. You can leave the development server running for
+the next step if you wish.
-
-=head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
-
-In some situations, it can be useful to run your application and
-display a page without using a browser. Catalyst lets you do this
-using the C<scripts/myapp_test.pl> script. Just supply the URL you
-wish to display and it will run that request through the normal
-controller dispatch logic and use the appropriate view to render the
-output (obviously, complex pages may dump a lot of text to your
-terminal window). For example, if you type:
-
- $ script/myapp_test.pl "/books/list"
-
-You should get the same text as if you visited
-L<http://localhost:3000/books/list> with the normal development server
-and asked your browser to view the page source.
+B<Note:> You will not see the authors yet because the view does not yet
+use the new relations. Read on to the next section where we update the
+template to do that.
=head1 UPDATING THE VIEW
-Let's add a new column to our book list page that takes advantage of
-the relationship information we manually added to our schema files
-in the previous section. Edit C<root/src/books/list.tt2> add add the
-following code below the existing table cell that contains
+Let's add a new column to our book list page that takes advantage of
+the relationship information we manually added to our schema files in
+the previous section. Edit C<root/src/books/list.tt2> add add the
+following code below the existing table cell that contains
C<book.rating> (IOW, add a new table cell below the existing two
-C<td> cells):
+C<E<lt>tdE<gt>> tags but above the closing C<E<lt>/trE<gt>> and
+C<E<lt>/tableE<gt>> tags):
+ ...
<td>
[% # First initialize a TT variable to hold a list. Then use a TT FOREACH -%]
[% # loop in 'side effect notation' to load just the last names of the -%]
[% # Use another TT vmethod to join & print the names & comma separators -%]
[% tt_authors.join(', ') | html %]
</td>
+ ...
-Then hit C<Ctrl+R> in your browser (note that you don't need to reload
+Then hit "Reload" in your browser (note that you don't need to reload
the development server or use the C<-r> option when updating TT
-templates) and you should now see the number of authors each book has
-along with a comma-separated list of the authors' last names.
+templates) and you should now see the number of authors each book has
+along with a comma-separated list of the authors' last names. (If you
+didn't leave the development server running from the previous step,
+you will obviously need to start it before you can refresh your
+browser window.)
+
+If you are still running the development server with C<DBIC_TRACE>
+enabled, you should also now see five more C<SELECT> statements in the
+debug output (one for each book as the authors are being retrieved by
+DBIC):
+
+ SELECT me.id, me.title, me.rating FROM books me:
+ SELECT author.id, author.first_name, author.last_name FROM book_authors me
+ JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '1'
+ SELECT author.id, author.first_name, author.last_name FROM book_authors me
+ JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '2'
+ SELECT author.id, author.first_name, author.last_name FROM book_authors me
+ JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '3'
+ SELECT author.id, author.first_name, author.last_name FROM book_authors me
+ JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '4'
+ SELECT author.id, author.first_name, author.last_name FROM book_authors me
+ JOIN authors author ON ( author.id = me.author_id ) WHERE ( me.book_id = ? ): '5'
+
+Also note in C<root/src/books/list.tt2> that we are using "| html", a
+type of TT filter, to escape characters such as E<lt> and E<gt> to <
+and > and avoid various types of dangerous hacks against your
+application. In a real application, you would probably want to put
+"| html" at the end of every field where a user has control over the
+information that can appear in that field (and can therefore inject
+markup or code if you don't "neutralize" those fields). In addition to
+"| html", Template Toolkit has a variety of other useful filters that
+can found in the documentation for
+L<Template::Filters|Template::Filters>.
-If you are still running the development server with C<DBIC_TRACE>
-enabled, you should also now see five more C<SELECT> statements in the
-debug output (one for each book as the authors are being retrieved by
-DBIC).
-Also note that we are using "| html", a type of TT filter, to escape
-characters such as E<lt> and E<gt> to < and > and avoid various
-types of dangerous hacks against your application. In a real
-application, you would probably want to put "| html" at the end of
-every field where a user has control over the information that can
-appear in that field (and can therefore inject markup or code if you
-don't "neutralize" those fields). In addition to "| html", Template
-Toolkit has a variety of other useful filters that can found in the
-documentation for L<Template::Filters|Template::Filters>.
+=head1 RUNNING THE APPLICATION FROM THE COMMAND LINE
+In some situations, it can be useful to run your application and
+display a page without using a browser. Catalyst lets you do this
+using the C<scripts/myapp_test.pl> script. Just supply the URL you
+wish to display and it will run that request through the normal
+controller dispatch logic and use the appropriate view to render the
+output (obviously, complex pages may dump a lot of text to your
+terminal window). For example, if you type:
-=head2 Using C<RenderView> for the Default View
+ $ script/myapp_test.pl "/books/list"
+
+You should get the same text as if you visited
+L<http://localhost:3000/books/list> with the normal development server
+and asked your browser to view the page source.
+
+
+=head1 OPTIONAL INFORMATION
-B<NOTE: The rest of this part of the tutorial is optional. You can
-skip to Part 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>,
+B<NOTE: The rest of this chapter of the tutorial is optional. You can
+skip to Chapter 4, L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>,
if you wish.>
-Once your controller logic has processed the request from a user, it
-forwards processing to your view in order to generate the appropriate
+
+=head2 Using C<RenderView> for the Default View
+
+Once your controller logic has processed the request from a user, it
+forwards processing to your view in order to generate the appropriate
response output. Catalyst uses
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by
-default to automatically performs this operation. If you look in
-C<lib/MyApp/Controller/Root.pm>, you should see the empty
+L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> by
+default to automatically performs this operation. If you look in
+C<lib/MyApp/Controller/Root.pm>, you should see the empty
definition for the C<sub end> method:
sub end : ActionClass('RenderView') {}
-The following bullet points provide a quick overview of the
+The following bullet points provide a quick overview of the
C<RenderView> process:
=over 4
=item *
-At the end of a given user request, Catalyst will call the most specific
-C<end> method that's appropriate. For example, if the controller for a
-request has an C<end> method defined, it will be called. However, if
-the controller does not define a controller-specific C<end> method, the
+At the end of a given user request, Catalyst will call the most specific
+C<end> method that's appropriate. For example, if the controller for a
+request has an C<end> method defined, it will be called. However, if
+the controller does not define a controller-specific C<end> method, the
"global" C<end> method in C<Root.pm> will be called.
=item *
=item *
-Because C<sub end> is empty, this effectively just runs the default
-logic in C<RenderView>. However, you can easily extend the
-C<RenderView> logic by adding your own code inside the empty method body
-(C<{}>) created by the Catalyst Helpers when we first ran the
-C<catalyst.pl> to initialize our application. See
-L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
+Because C<sub end> is empty, this effectively just runs the default
+logic in C<RenderView>. However, you can easily extend the
+C<RenderView> logic by adding your own code inside the empty method body
+(C<{}>) created by the Catalyst Helpers when we first ran the
+C<catalyst.pl> to initialize our application. See
+L<Catalyst::Action::RenderView|Catalyst::Action::RenderView> for more
detailed information on how to extended C<RenderView> in C<sub end>.
=back
=head2 Using The Default Template Name
-By default, C<Catalyst::View::TT> will look for a template that uses the
-same name as your controller action, allowing you to save the step of
-manually specifying the template name in each action. For example, this
-would allow us to remove the
-C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our
-C<list> action in the Books controller. Open
+By default, C<Catalyst::View::TT> will look for a template that uses the
+same name as your controller action, allowing you to save the step of
+manually specifying the template name in each action. For example, this
+would allow us to remove the
+C<$c-E<gt>stash-E<gt>{template} = 'books/list.tt2';> line of our
+C<list> action in the Books controller. Open
C<lib/MyApp/Controller/Books.pm> in your editor and comment out this line
to match the following (only the C<$c-E<gt>stash-E<gt>{template}> line
has changed):
#$c->stash->{template} = 'books/list.tt2';
}
-C<Catalyst::View::TT> defaults to looking for a template with no
-extension. In our case, we need to override this to look for an
-extension of C<.tt2>. Open C<lib/MyApp/View/TT.pm> and add the
-C<TEMPLATE_EXTENSION> definition as follows:
- __PACKAGE__->config({
- CATALYST_VAR => 'Catalyst',
- INCLUDE_PATH => [
- MyApp->path_to( 'root', 'src' ),
- MyApp->path_to( 'root', 'lib' )
- ],
- PRE_PROCESS => 'config/main',
- WRAPPER => 'site/wrapper',
- ERROR => 'error.tt2',
- TIMER => 0,
- TEMPLATE_EXTENSION => '.tt2',
- });
-
-You should now be able to restart the development server as per the
+You should now be able to restart the development server as per the
previous section and access the L<http://localhost:3000/books/list>
as before.
B<NOTE:> Please note that if you use the default template technique,
you will B<not> be able to use either the C<$c-E<gt>forward> or
-the C<$c-E<gt>detach> mechanisms (these are discussed in Part 2 and
-Part 9 of the Tutorial).
+the C<$c-E<gt>detach> mechanisms (these are discussed in Chapter 2 and
+Chapter 9 of the Tutorial).
=head2 Return To A Manually-Specified Template
$c->stash->{template} = 'books/list.tt2';
-Then delete the C<TEMPLATE_EXTENSION> line in
+Then delete the C<TEMPLATE_EXTENSION> line in
C<lib/MyApp/View/TT.pm>.
-You should then be able to restart the development server and
+You should then be able to restart the development server and
access L<http://localhost:3000/books/list> in the same manner as
with earlier sections.
Please report any errors, issues or suggestions to the author. The
most recent version of the Catalyst Tutorial can be found at
-L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>.
+L<http://dev.catalyst.perl.org/repos/Catalyst/Catalyst-Manual/5.70/trunk/lib/Catalyst/Manual/Tutorial/>.
Copyright 2006-2008, Kennedy Clark, under Creative Commons License
(L<http://creativecommons.org/licenses/by-sa/3.0/us/>).
-
projects / catagits/Catalyst-Manual.git / blobdiff