=head1 DESCRIPTION
-This is a brief overview of why and how to use Catalyst. It explains how
-Catalyst works and shows how to get a simple application up and running quickly.
+This is a brief introduction to Catalyst. It explains the most important
+features of how Catalyst works and shows how to get a simple application
+up and running quickly. For an introduction (without code) to Catalyst
+itself, and why you should be using it, see L<Catalyst::Manual::About>.
+For a systematic step-by-step introduction to writing an application
+with Catalyst, see L<Catalyst::Manual::Tutorial>.
=head2 What is Catalyst?
-Catalyst is an elegant web application framework, extremely flexible yet
-extremely simple. It's similar to Ruby on Rails, Spring (Java) and L<Maypole>,
-upon which it was originally based.
+Catalyst is an elegant web application framework, extremely flexible
+yet extremely simple. It's similar to Ruby on Rails, Spring (Java),
+and L<Maypole>, upon which it was originally based. Its most important
+design philosphy is to provide easy access to all the tools you need
+to develop web applications, with few restrictions on how you need to
+use these tools. However, this does mean that it is always possible to
+do things in a different way. Other web frameworks are B<initially>
+simpler to use, but achieve this by locking the programmer into a
+single set of tools. Catalyst's emphasis on flexibility means that you
+have to think more to use it. We view this as a feature. For example,
+this leads to Catalyst being more suited to system integration tasks
+than other web frameworks.
=head3 MVC
-Catalyst follows the Model-View-Controller (MVC) design pattern, allowing you to
-easily separate concerns, like content, presentation, and flow control, into
-separate modules. This separation allows you to modify code that handles one
-concern without affecting code that handles the others. Catalyst promotes the
-re-use of existing Perl modules that already handle common web application
-concerns well.
+Catalyst follows the Model-View-Controller (MVC) design pattern,
+allowing you to easily separate concerns, like content, presentation,
+and flow control, into separate modules. This separation allows you to
+modify code that handles one concern without affecting code that handles
+the others. Catalyst promotes the re-use of existing Perl modules that
+already handle common web application concerns well.
-Here's how the M, V, and C map to those concerns, with examples of well-known
-Perl modules you may want to use for each.
+Here's how the Model, View, and Controller map to those concerns, with
+examples of well-known Perl modules you may want to use for each.
=over 4
=item * B<Model>
-Access and modify content (data). L<Class::DBI>, L<Plucene>, L<Net::LDAP>...
+Access and modify content (data). L<DBIx::Class>, L<Class::DBI>,
+L<Xapian>, L<Net::LDAP>...
=item * B<View>
-Present content to the user. L<Template Toolkit|Template>, L<Mason|HTML::Mason>,
-L<HTML::Template>...
+Present content to the user. L<Template Toolkit|Template>,
+L<Mason|HTML::Mason>, L<HTML::Template>...
=item * B<Controller>
Control the whole request phase, check parameters, dispatch actions, flow
-control. Catalyst!
+control. Catalyst itself!
=back
-If you're unfamiliar with MVC and design patterns, you may want to check
-out the original book on the subject, I<Design Patterns>, by Gamma,
-Helm, Johnson, and Vlissides, also known as the Gang of Four (GoF). You
-can also just Google it. Many, many web application frameworks are
-based on MVC, including all those listed above.
+If you're unfamiliar with MVC and design patterns, you may want to
+check out the original book on the subject, I<Design Patterns>, by
+Gamma, Helm, Johnson, and Vlissides, also known as the Gang of Four
+(GoF). Many, many web application frameworks are based on MVC, which
+is becoming a popular design paradigm for the world wide web.
=head3 Flexibility
-Catalyst is much more flexible than many other frameworks. We'll talk more about
-this later, but rest assured you can use your favorite Perl modules with
-Catalyst.
+Catalyst is much more flexible than many other frameworks. Rest assured
+you can use your favorite Perl modules with Catalyst.
=over 4
=item * B<Multiple Models, Views, and Controllers>
-To build a Catalyst application, you handle each type of concern inside special
-modules called L</Components>. Often this code will be very simple, just calling
-out to Perl modules like those listed above under L</MVC>. Catalyst handles
-these components in a very flexible way. Use as many Models, Views, and
-Controllers as you like, using as many different Perl modules as you like, all
-in the same application. Want to manipulate multiple databases, and retrieve
-some data via LDAP? No problem. Want to present data from the same Model using
-L<Template Toolkit|Template> and L<PDF::Template>? Easy.
+To build a Catalyst application, you handle each type of concern inside
+special modules called L</Components>. Often this code will be very
+simple, just calling out to Perl modules like those listed above under
+L</MVC>. Catalyst handles these components in a very flexible way. Use
+as many Models, Views, and Controllers as you like, using as many
+different Perl modules as you like, all in the same application. Want to
+manipulate multiple databases, and retrieve some data via LDAP? No
+problem. Want to present data from the same Model using L<Template
+Toolkit|Template> and L<PDF::Template>? Easy.
=item * B<Reuseable Components>
-Not only does Catalyst promote the re-use of already existing Perl modules, it
-also allows you to re-use your Catalyst components in multiple Catalyst
-applications.
+Not only does Catalyst promote the re-use of already existing Perl
+modules, it also allows you to re-use your Catalyst components in
+multiple Catalyst applications.
=item * B<Unrestrained URL-to-Action Dispatching>
-Catalyst allows you to dispatch any URLs to any application L<Actions>, even
-through regular expressions! Unlike most other frameworks, it doesn't require
-mod_rewrite or class and method names in URLs.
+Catalyst allows you to dispatch any URLs to any application L</Actions>,
+even through regular expressions! Unlike most other frameworks, it
+doesn't require mod_rewrite or class and method names in URLs.
-With Catalyst you register your actions and address them directly. For example:
+With Catalyst you register your actions and address them directly. For
+example:
sub hello : Global {
my ( $self, $context ) = @_;
- $context->response->output('Hello World!');
+ $context->response->body('Hello World!');
}
Now http://localhost:3000/hello prints "Hello World!".
-=item * B<Support for CGI, mod_perl, Apache::Request>
+=item * B<Support for CGI, mod_perl, Apache::Request, FastCGI>
-Use L<Catalyst::Engine::Apache> or L<Catalyst::Engine::CGI>.
+Use L<Catalyst::Engine::Apache> or L<Catalyst::Engine::CGI>. Other
+engines are also available.
=back
=head3 Simplicity
-The best part is that Catalyst implements all this flexibility in a very simple
-way.
+The best part is that Catalyst implements all this flexibility in a very
+simple way.
=over 4
=item * B<Building Block Interface>
-Components interoperate very smoothly. For example, Catalyst automatically makes
-a L<Context> object available to every component. Via the context, you can
-access the request object, share data between components, and control the flow
-of your application. Building a Catalyst application feels a lot like snapping
+Components interoperate very smoothly. For example, Catalyst
+automatically makes a L</Context> object available to every
+component. Via the context, you can access the request object, share
+data between components, and control the flow of your
+application. Building a Catalyst application feels a lot like snapping
together toy building blocks, and everything just works.
=item * B<Component Auto-Discovery>
-No need to C<use> all of your components. Catalyst automatically finds and loads
-them.
+No need to C<use> all of your components. Catalyst automatically finds
+and loads them.
=item * B<Pre-Built Components for Popular Modules>
-See L<Catalyst::Model::CDBI> for L<Class::DBI>, or L<Catalyst::View::TT> for
-L<Template Toolkit|Template>. You can even get an instant web database front end
-with L<Catalyst::Model::CDBI::CRUD>.
+See L<Catalyst::Model::DBIC::Schema> for L<DBIx::Class>, or
+L<Catalyst::View::TT> for L<Template Toolkit|Template>.
=item * B<Built-in Test Framework>
-Catalyst comes with a built-in, lightweight http server and test framework,
-making it easy to test applications from the command line.
+Catalyst comes with a built-in, lightweight http server and test
+framework, making it easy to test applications from the web browser,
+and the command line.
=item * B<Helper Scripts>
-Catalyst provides helper scripts to quickly generate running starter code for
-components and unit tests.
+Catalyst provides helper scripts to quickly generate running starter
+code for components and unit tests. Install L<Catalyst::Devel> and see
+L<Catalyst::Helper>.
=back
=head2 Quickstart
-Here's how to install Catalyst and get a simple application up and running,
-using the helper scripts described above.
+Here's how to install Catalyst and get a simple application up and
+running, using the helper scripts described above.
=head3 Install
- $ perl -MCPAN -e 'install Bundle::Catalyst'
+Installation of Catalyst can be a time-consuming and frustrating
+effort, due to its large number of dependencies. The easiest way
+to get up and running is to use Matt Trout's C<cat-install>
+script, from L<http://www.shadowcatsystems.co.uk/static/cat-install>,
+and then install L<Catalyst::Devel>.
+
+ # perl cat-install
+ # perl -MCPAN -e 'install Catalyst::Devel'
=head3 Setup
Now visit these locations with your favorite browser or user agent to see
Catalyst in action:
+(NOTE: Although we create a controller here, we don't actually use it.
+Both of these URLs should take you to the welcome page.)
+
+
=over 4
=item http://localhost:3000/
=back
-Dead easy!
-
=head2 How It Works
-Let's see how Catalyst works, by taking a closer look at the components and
-other parts of a Catalyst application.
+Let's see how Catalyst works, by taking a closer look at the components
+and other parts of a Catalyst application.
+
+=head3 Components
+
+Catalyst has an uncommonly flexible component system. You can define as
+many L</Models>, L</Views>, and L</Controllers> as you like. As discussed
+previously, the general idea is that the View is responsible for the
+output of data to the user (typically via a web browser, but a View can
+also generate PDFs or e-mails, for example); the Model is responsible
+for providing data (typically from a relational database); and the
+Controller is responsible for interacting with the user and deciding
+how user input determines what actions the application takes.
+
+In the world of MVC, there are frequent discussions and disagreements
+about the nature of each element - whether certain types of logic
+belong in the Model or the Controller, etc. Catalyst's flexibility
+means that this decision is entirely up to you, the programmer;
+Catalyst doesn't enforce anything. See L<Catalyst::Manual::About> for
+a general discussion of these issues.
+
+All components must inherit from L<Catalyst::Base>, which provides a
+simple class structure and some common class methods like C<config> and
+C<new> (constructor).
+
+ package MyApp::Controller::Catalog;
+
+ use strict;
+ use base 'Catalyst::Base';
+
+ __PACKAGE__->config( foo => 'bar' );
+
+ 1;
+
+You don't have to C<use> or otherwise register Models, Views, and
+Controllers. Catalyst automatically discovers and instantiates them
+when you call C<setup> in the main application. All you need to do is
+put them in directories named for each Component type. You can use a
+short alias for each one.
+
+=over 4
+
+=item * B<MyApp/Model/>
+
+=item * B<MyApp/M/>
+
+=item * B<MyApp/View/>
+
+=item * B<MyApp/V/>
+
+=item * B<MyApp/Controller/>
+
+=item * B<MyApp/C/>
+
+=back
+
+In older versions of Catalyst, the recommended practice (and the one
+automatically created by helper scripts) was to name the directories
+C<M/>, C<V/>, and C<C/>. Though these still work, we now recommend
+the use of the full names.
+
+=head4 Views
+
+To show how to define views, we'll use an already-existing base class for the
+L<Template Toolkit|Template>, L<Catalyst::View::TT>. All we need to do is
+inherit from this class:
+
+ package MyApp::View::TT;
+
+ use strict;
+ use base 'Catalyst::View::TT';
+
+ 1;
+
+(You can also generate this automatically by using the helper script:
+
+ script/myapp_create.pl view TT TT
+
+where the first C<TT> tells the script that the name of the view should
+be C<TT>, and the second that it should be a Template Toolkit view.)
+
+This gives us a process() method and we can now just do
+$c->forward('MyApp::View::TT') to render our templates. The base class
+makes process() implicit, so we don't have to say
+C<$c-E<gt>forward(qw/MyApp::View::TT process/)>.
+
+ sub hello : Global {
+ my ( $self, $c ) = @_;
+ $c->stash->{template} = 'hello.tt';
+ }
+
+ sub end : Private {
+ my ( $self, $c ) = @_;
+ $c->forward( $c->view('TT') );
+ }
+
+You normally render templates at the end of a request, so it's a perfect
+use for the global C<end> action.
+
+In practice, however, you would use a default C<end> action as supplied
+by L<Catalyst::Action::RenderView>.
+
+Also, be sure to put the template under the directory specified in
+C<$c-E<gt>config-E<gt>{root}>, or you'll end up looking at the debug
+screen.
+
+=head4 Models
+
+Models are providers of data. This data could come from anywhere - a
+search engine index, a spreadsheet, the file system - but typically a
+Model represents a database table. The data source does not
+intrinsically have much to do with web applications or Catalyst - it
+could just as easily be used to write an offline report generator or a
+command-line tool.
+
+To show how to define models, again we'll use an already-existing base
+class, this time for L<DBIx::Class>: L<Catalyst::Model::DBIC::Schema>.
+We'll also need L<DBIx::Class::Schema::Loader>.
+
+But first, we need a database.
+
+ -- myapp.sql
+ CREATE TABLE foo (
+ id INTEGER PRIMARY KEY,
+ data TEXT
+ );
+
+ CREATE TABLE bar (
+ id INTEGER PRIMARY KEY,
+ foo INTEGER REFERENCES foo,
+ data TEXT
+ );
+
+ INSERT INTO foo (data) VALUES ('TEST!');
+
+ % sqlite /tmp/myapp.db < myapp.sql
+
+Now we can create a DBIC::Schema model for this database.
+
+ script/myapp_create.pl model MyModel DBIC::Schema MySchema create=static 'dbi:SQLite:/tmp/myapp.db'
+
+L<DBIx::Class::Schema::Loader> automatically loads table layouts and
+relationships, and converts them into a static schema definition C<MySchema>,
+which you can edit later.
+
+Use the stash to pass data to your templates.
+
+We add the following to MyApp/Controller/Root.pm
+
+ sub view : Global {
+ my ( $self, $c, $id ) = @_;
+
+ $c->stash->{item} = $c->model('MyModel::Foo')->find($id);
+ }
+
+ 1;
+
+ sub end : Private {
+ my ( $self, $c ) = @_;
+
+ $c->stash->{template} ||= 'index.tt';
+ $c->forward( $c->view('TT') );
+ }
+
+We then create a new template file "root/index.tt" containing:
+
+ The Id's data is [% item.data %]
+
+Models do not have to be part of your Catalyst application; you
+can always call an outside module that serves as your Model:
+
+ # in a Controller
+ sub list : Local {
+ my ( $self, $c ) = @_;
+
+ $c->stash->{template} = 'list.tt';
+
+ use Some::Outside::Database::Module;
+ my @records = Some::Outside::Database::Module->search({
+ artist => 'Led Zeppelin',
+ });
+
+ $c->stash->{records} = \@records;
+ }
+
+But by using a Model that is part of your Catalyst application, you
+gain several things: you don't have to C<use> each component, Catalyst
+will find and load it automatically at compile-time; you can
+C<forward> to the module, which can only be done to Catalyst
+components. Only Catalyst components can be fetched with
+C<$c-E<gt>model('SomeModel')>.
+
+Happily, since many people have existing Model classes that they
+would like to use with Catalyst (or, conversely, they want to
+write Catalyst models that can be used outside of Catalyst, e.g.
+in a cron job), it's trivial to write a simple component in
+Catalyst that slurps in an outside Model:
+
+ package MyApp::Model::DB;
+ use base qw/Catalyst::Model::DBIC::Schema/;
+ __PACKAGE__->config(
+ schema_class => 'Some::DBIC::Schema',
+ connect_info => ['dbi:SQLite:foo.db', '', '', {AutoCommit=>1}]
+ );
+ 1;
+
+and that's it! Now C<Some::DBIC::Schema> is part of your
+Cat app as C<MyApp::Model::DB>.
+
+Within Catalyst, the common approach to writing a model for your
+application is wrapping a generic model (e.g. L<DBIx::Class::Schema>, a
+bunch of XMLs, or anything really) with an object that contains
+configuration data, convenience methods, and so forth. Thus you
+will in effect have two models - a wrapper model that knows something
+about Catalyst and your web application, and a generic model that is
+totally independent of these needs.
+
+Technically, within Catalyst a model is a B<component> - an instance of
+the model's class belonging to the application. It is important to
+stress that the lifetime of these objects is per application, not per
+request.
+
+While the model base class (L<Catalyst::Model>) provides things like
+C<config> to better integrate the model into the application, sometimes
+this is not enough, and the model requires access to C<$c> itself.
+
+Situations where this need might arise include:
+
+=over 4
+
+=item *
+
+Interacting with another model
+
+=item *
+
+Using per-request data to control behavior
+
+=item *
+
+Using plugins from a Model (for example L<Catalyst::Plugin::Cache>).
+
+=back
+
+From a style perspective it's usually considered bad form to make your
+model "too smart" about things - it should worry about business logic
+and leave the integration details to the controllers. If, however, you
+find that it does not make sense at all to use an auxillary controller
+around the model, and the model's need to access C<$c> cannot be
+sidestepped, there exists a power tool called L</ACCEPT_CONTEXT>.
+
+=head4 Controllers
+
+Multiple controllers are a good way to separate logical domains of your
+application.
+
+ package MyApp::Controller::Login;
+
+ use base qw/Catalyst::Controller/;
+
+ sub login : Path("login") { }
+ sub new_password : Path("new-password") { }
+ sub logout : Path("logout") { }
+
+ package MyApp::Controller::Catalog;
+
+ use base qw/Catalyst::Controller/;
+
+ sub view : Local { }
+ sub list : Local { }
+
+ package MyApp::Controller::Cart;
+
+ use base qw/Catalyst::Controller/;
+
+ sub add : Local { }
+ sub update : Local { }
+ sub order : Local { }
+
+Note that you can also supply attributes via the Controller's config so
+long as you have at least one attribute on a subref to be exported
+(:Action is commonly used for this) - for example the following is
+equivalent to the same controller above:
+
+ package MyApp::Controller::Login;
+
+ use base qw/Catalyst::Controller/;
+
+ __PACKAGE__->config(
+ actions => {
+ 'sign_in' => { Path => 'sign-in' },
+ 'new_password' => { Path => 'new-password' },
+ 'sign_out' => { Path => 'sign-out' },
+ },
+ );
+
+ sub sign_in : Action { }
+ sub new_password : Action { }
+ sub sign_out : Action { }
+
+=head3 ACCEPT_CONTEXT
+
+Whenever you call $c->component("Foo") you get back an object - the
+instance of the model. If the component supports the C<ACCEPT_CONTEXT>
+method instead of returning the model itself, the return value of C<<
+$model->ACCEPT_CONTEXT( $c ) >> will be used.
+
+This means that whenever your model/view/controller needs to talk to C<$c> it
+gets a chance to do this when it's needed.
+
+A typical C<ACCEPT_CONTEXT> method will either clone the model and return one
+with the context object set, or it will return a thin wrapper that contains
+C<$c> and delegates to the per-application model object.
+
+A typical C<ACCEPT_CONTEXT> method could look like this:
+
+ sub ACCEPT_CONTEXT {
+ my ( $self, $c, @extra_arguments ) = @_;
+ bless { %$self, c => $c }, ref($self);
+ }
+
+effectively treating $self as a B<prototype object> that gets a new parameter.
+C<@extra_arguments> comes from any trailing arguments to
+C<< $c->component( $bah, @extra_arguments ) >> (or C<< $c->model(...) >>,
+C<< $c->view(...) >> etc).
+
+The life time of this value is B<per usage>, and not per request. To make this
+per request you can use the following technique:
+
+Add a field to C<$c>, like C<my_model_instance>. Then write your
+C<ACCEPT_CONTEXT> method to look like this:
+
+ sub ACCEPT_CONTEXT {
+ my ( $self, $c ) = @_;
+
+ if ( my $per_request = $c->my_model_instance ) {
+ return $per_request;
+ } else {
+ my $new_instance = bless { %$self, c => $c }, ref($self);
+ Scalar::Util::weaken($new_instance->{c}); # or we have a circular reference
+ $c->my_model_instance( $new_instance );
+ return $new_instance;
+ }
+ }
=head3 Application Class
-In addition to the Model, View, and Controller components, there's a single
-class that represents your application itself. This is where you configure your
-application, load plugins, define application-wide actions, and extend Catalyst.
+In addition to the Model, View, and Controller components, there's a
+single class that represents your application itself. This is where you
+configure your application, load plugins, and extend Catalyst.
package MyApp;
use strict;
- use Catalyst qw/-Debug/;
+ use Catalyst qw/-Debug/; # Add other plugins here, e.g.
+ # for session support
MyApp->config(
name => 'My Application',
- root => '/home/joeuser/myapp/root',
# You can put anything else you want in here:
my_configuration_variable => 'something',
);
-
- sub default : Private {
- my ( $self, $context ) = @_;
- $context->response->output('Catalyst rockz!');
- }
-
1;
-For most applications, Catalyst requires you to define only two config
-parameters:
+In older versions of Catalyst, the application class was where you put
+global actions. However, as of version 5.66, the recommended practice is
+to place such actions in a special Root controller (see L</Actions>,
+below), to avoid namespace collisions.
=over 4
=item * B<name>
-Name of your application.
-
-=item * B<root>
-
-Path to additional files such as templates, images, or other static data.
+The name of your application.
=back
-However, you can define as many parameters as you want for plugins or whatever
-you need. You can access them anywhere in your application via
+Optionally, you can specify a B<root> parameter for templates and static
+data. If omitted, Catalyst will try to auto-detect the directory's
+location. You can define as many parameters as you want for plugins or
+whatever you need. You can access them anywhere in your application via
C<$context-E<gt>config-E<gt>{$param_name}>.
=head3 Context
-Catalyst automatically blesses a Context object into your application class and
-makes it available everywhere in your application. Use the Context to directly
-interact with Catalyst and glue your L<Components> together. For example, if you
-need to use the Context from within a Template Toolkit template, it's already
-there:
+Catalyst automatically blesses a Context object into your application
+class and makes it available everywhere in your application. Use the
+Context to directly interact with Catalyst and glue your L</Components>
+together. For example, if you need to use the Context from within a
+Template Toolkit template, it's already there:
<h1>Welcome to [% c.config.name %]!</h1>
-As illustrated earlier in our URL-to-Action dispatching example, the Context is
-always the second method parameter, behind the Component object reference or
-class name itself. Previously we called it C<$context> for clarity, but most
-Catalyst developers just call it C<$c>:
+As illustrated in our URL-to-Action dispatching example, the Context is
+always the second method parameter, behind the Component object
+reference or class name itself. Previously we called it C<$context> for
+clarity, but most Catalyst developers just call it C<$c>:
sub hello : Global {
my ( $self, $c ) = @_;
- $c->res->output('Hello World!');
+ $c->res->body('Hello World!');
}
The Context contains several important objects:
$c->req->cookies->{sessionid};
$c->req->headers->content_type;
$c->req->base;
+ $c->req->uri_with( { page = $pager->next_page } );
=item * L<Catalyst::Response>
The response is like the request, but contains just response-specific
information.
- $c->res->output('Hello World');
+ $c->res->body('Hello World');
$c->res->status(404);
$c->res->redirect('http://oook.de');
=item * L<Catalyst::Config>
$c->config
-
$c->config->root;
$c->config->name;
=item * L<Catalyst::Log>
$c->log
-
$c->log->debug('Something happened');
$c->log->info('Something you should know');
=item * B<Stash>
$c->stash
-
$c->stash->{foo} = 'bar';
+ $c->stash->{baz} = {baz => 'qox'};
+ $c->stash->{fred} = [qw/wilma pebbles/];
+
+and so on.
=back
sub show_message : Private {
my ( $self, $c ) = @_;
- $c->res->output( $c->stash->{message} );
+ $c->res->body( $c->stash->{message} );
}
-Note that the stash should be used only for passing data in an individual
-request cycle; it gets cleared at a new request. If you need to maintain more
-persistent data, use a session.
+Note that the stash should be used only for passing data in an
+individual request cycle; it gets cleared at a new request. If you need
+to maintain persistent data, use a session. See
+L<Catalyst::Plugin::Session> for a comprehensive set of
+Catalyst-friendly session-handling tools.
=head3 Actions
-A Catalyst controller is defined by its actions. An action is a sub with a
-special attribute. You've already seen some examples of actions in this
-document. The URL (for example http://localhost.3000/foo/bar) consists of two
-parts, the base (http://localhost:3000/ in this example) and the path (foo/bar).
-Please note that the trailing slash after the hostname[:port] always belongs to
+A Catalyst controller is defined by its actions. An action is a
+subroutine with a special attribute. You've already seen some examples
+of actions in this document. The URL (for example
+http://localhost.3000/foo/bar) consists of two parts, the base
+(http://localhost:3000/ in this example) and the path (foo/bar). Please
+note that the trailing slash after the hostname[:port] always belongs to
base and not to the action.
+=over 4
+
+=item * B<Application Wide Actions>
+
+Actions which are called at the root level of the application
+(e.g. http://localhost:3000/ ) go in MyApp::Controller::Root, like
+this:
+
+ package MyApp::Controller::Root;
+ use base 'Catalyst::Controller';
+ # Sets the actions in this controller to be registered with no prefix
+ # so they function identically to actions created in MyApp.pm
+ __PACKAGE__->config->{namespace} = '';
+ sub default : Private {
+ my ( $self, $context ) = @_;
+ $context->response->body('Catalyst rocks!');
+ }
+ 1;
+
+=back
+
+=head4 Action types
+
Catalyst supports several types of actions:
=over 4
-=item * B<Literal>
+=item * B<Literal> (B<Path> actions)
+ package MyApp::Controller::My::Controller;
sub bar : Path('foo/bar') { }
+Literal C<Path> actions will act relative to their current
+namespace. The above example matches only
+http://localhost:3000/my/controller/foo/bar. If you start your path with
+a forward slash, it will match from the root. Example:
+
+ package MyApp::Controller::My::Controller;
+ sub bar : Path('/foo/bar') { }
+
Matches only http://localhost:3000/foo/bar.
+ package MyApp::Controller::My::Controller;
+ sub bar : Path { }
+
+By leaving the C<Path> definition empty, it will match on the namespace
+root. The above code matches http://localhost:3000/my/controller.
+
=item * B<Regex>
sub bar : Regex('^item(\d+)/order(\d+)$') { }
Matches any URL that matches the pattern in the action key, e.g.
-http://localhost:3000/item23/order42. The '' around the regexp is optional, but
-perltidy likes it. :)
+http://localhost:3000/item23/order42. The '' around the regexp is
+optional, but perltidy likes it. :)
+
+Regex matches act globally, i.e. without reference to the namespace from
+which it is called, so that a C<bar> method in the
+C<MyApp::Controller::Catalog::Order::Process> namespace won't match any
+form of C<bar>, C<Catalog>, C<Order>, or C<Process> unless you
+explicitly put this in the regex. To achieve the above, you should
+consider using a C<LocalRegex> action.
-Regex matches act globally, i.e. without reference to the namespace from which
-it is called, so that a C<bar> method in the
-C<MyApp::Controller::Catalog::Order::Process> namespace won't match any form of
-C<bar>, C<Catalog>, C<Order>, or C<Process> unless you explicitly put this in
-the regex.
+=item * B<LocalRegex>
-If you use capturing parentheses to extract values within the matching URL (23,
-42 in the above example), those values are available in the $c->req->snippets
-array. If you want to pass arguments at the end of your URL, you must use regex
-action keys. See L</URL Argument Handling> below.
+ sub bar : LocalRegex('^widget(\d+)$') { }
-=item * B<Top-level>
+LocalRegex actions act locally. If you were to use C<bar> in
+C<MyApp::Controller::Catalog>, the above example would match urls like
+http://localhost:3000/catalog/widget23.
- package MyApp;
+If you omit the "C<^>" from your regex, then it will match any depth
+from the controller and not immediately off of the controller name. The
+following example differs from the above code in that it will match
+http://localhost:3000/catalog/foo/widget23 as well.
+
+ package MyApp::Controller::Catalog;
+ sub bar : LocalRegex('widget(\d+)$') { }
+
+For both LocalRegex and Regex actions, if you use capturing parentheses
+to extract values within the matching URL, those values are available in
+the C<$c-E<gt>req-E<gt>captures> array. In the above example, "widget23"
+would capture "23" in the above example, and
+C<$c-E<gt>req-E<gt>captures-E<gt>[0]> would be "23". If you want to pass
+arguments at the end of your URL, you must use regex action keys. See
+L</URL Path Handling> below.
+
+=item * B<Top-level> (B<Global>)
+
+ package MyApp::Controller::Foo;
sub foo : Global { }
-Matches http://localhost:3000/foo. The function name is mapped directly
-to the application base.
+Matches http://localhost:3000/foo. The function name is mapped
+directly to the application base. You can provide an equivalent
+function in this case by doing the following:
-=item * B<Namespace-Prefixed>
+ package MyApp::Controller::Root
+ sub foo : Local { }
+
+=item * B<Namespace-Prefixed> (B<Local>)
- package MyApp::C::My::Controller;
+ package MyApp::Controller::My::Controller;
sub foo : Local { }
Matches http://localhost:3000/my/controller/foo.
This action type indicates that the matching URL must be prefixed with a
-modified form of the component's class (package) name. This modified class name
-excludes the parts that have a pre-defined meaning in Catalyst ("MyApp::C" in
-the above example), replaces "::" with "/", and converts the name to lower case.
-See L</Components> for a full explanation of the pre-defined meaning of Catalyst
-component class names.
+modified form of the component's class (package) name. This modified
+class name excludes the parts that have a pre-defined meaning in
+Catalyst ("MyApp::Controller" in the above example), replaces "::" with
+"/", and converts the name to lower case. See L</Components> for a full
+explanation of the pre-defined meaning of Catalyst component class
+names.
+
+=item * B<Chained>
+
+Catalyst also provides a method to build and dispatch chains of actions,
+like
+
+ sub catalog : Chained : CaptureArgs(1) {
+ my ( $self, $c, $arg ) = @_;
+ ...
+ }
+
+ sub item : Chained('catalog') : Args(1) {
+ my ( $self, $c, $arg ) = @_;
+ ...
+ }
+
+to handle a C</catalog/*/item/*> path. For further information about this
+dispatch type, please see L<Catalyst::DispatchType::Chained>.
=item * B<Private>
sub foo : Private { }
-Matches no URL, and cannot be executed by requesting a URL that corresponds to
-the action key. Private actions can be executed only inside a Catalyst
-application, by calling the C<forward> method:
+Matches no URL, and cannot be executed by requesting a URL that
+corresponds to the action key. Private actions can be executed only
+inside a Catalyst application, by calling the C<forward> method:
$c->forward('foo');
from elsewhere, be reached with
C<$c-E<gt>forward('/catalog/order/process/bar')>.
+=item * B<Args>
+
+Args is not an action type per se, but an action modifier - it adds a
+match restriction to any action it's provided to, requiring only as many
+path parts as are specified for the action to be valid - for example in
+MyApp::Controller::Foo,
+
+ sub bar :Local
+
+would match any URL starting /foo/bar/. To restrict this you can do
+
+ sub bar :Local :Args(1)
+
+to only match /foo/bar/*/
+
=back
B<Note:> After seeing these examples, you probably wonder what the point
-is of defining names for regex and path actions. Actually, every public
-action is also a private one, so you have one unified way of addressing
-components in your C<forward>s.
+is of defining names for regex and path actions. Every public action is
+also a private one, so you have one unified way of addressing components
+in your C<forward>s.
=head4 Built-in Private Actions
displaying a generic frontpage for the main app, or an error page for
individual controllers.
+If C<default> isn't acting how you would expect, look at using a
+L</Literal> C<Path> action (with an empty path string). The difference
+is that C<Path> takes arguments relative from the namespace and
+C<default> I<always> takes arguments relative from the root, regardless
+of what controller it's in. Indeed, this is now the recommended way of
+handling default situations; the C<default> private controller should
+be considered deprecated.
+
+=item * B<index : Private>
+
+C<index> is much like C<default> except that it takes no arguments
+and it is weighted slightly higher in the matching process. It is
+useful as a static entry point to a controller, e.g. to have a static
+welcome page. Note that it's also weighted higher than Path.
+
=item * B<begin : Private>
Called at the beginning of a request, before any matching actions are
=head4 Built-in actions in controllers/autochaining
- Package MyApp::C::Foo;
+ Package MyApp::Controller::Foo;
sub begin : Private { }
sub default : Private { }
sub auto : Private { }
well. The actions will override the ones in less-specific controllers,
or your application class. In other words, for each of the three
built-in private actions, only one will be run in any request
-cycle. Thus, if C<MyApp::C::Catalog::begin> exists, it will be run in
-place of C<MyApp::begin> if you're in the C<catalog> namespace, and
-C<MyApp::C::Catalog::Order::begin> would override this in turn.
+cycle. Thus, if C<MyApp::Controller::Catalog::begin> exists, it will be
+run in place of C<MyApp::begin> if you're in the C<catalog> namespace,
+and C<MyApp::Controller::Catalog::Order::begin> would override this in
+turn.
+
+=over 4
+
+=item * B<auto : Private>
In addition to the normal built-in actions, you have a special action
for making chains, C<auto>. Such C<auto> actions will be run after any
the I<most> specific class. I<This is the reverse of the order in which
the normal built-ins override each other>.
+=back
+
Here are some examples of the order in which the various built-ins
would be called:
MyApp::begin
MyApp::auto
- MyApp::C::Foo::default # in the absence of MyApp::C::Foo::Foo
+ MyApp::Controller::Foo::default # in the absence of MyApp::Controller::Foo::Foo
MyApp::end
=item for a request for C</foo/bar/foo>
- MyApp::C::Foo::Bar::begin
+ MyApp::Controller::Foo::Bar::begin
MyApp::auto
- MyApp::C::Foo::auto
- MyApp::C::Foo::Bar::auto
- MyApp::C::Foo::Bar::default # for MyApp::C::Foo::Bar::foo
- MyApp::C::Foo::Bar::end
+ MyApp::Controller::Foo::auto
+ MyApp::Controller::Foo::Bar::auto
+ MyApp::Controller::Foo::Bar::default # for MyApp::Controller::Foo::Bar::foo
+ MyApp::Controller::Foo::Bar::end
=back
=item for a request for C</foo/bar/foo> where first C<auto> returns
false
- MyApp::C::Foo::Bar::begin
+ MyApp::Controller::Foo::Bar::begin
MyApp::auto
- MyApp::C::Foo::Bar::end
+ MyApp::Controller::Foo::Bar::end
=back
for that URL.
B<Note:> Looking at it another way, C<auto> actions have to return a
-true value to continue processing! You can also C<die> in the autochain
+true value to continue processing! You can also C<die> in the auto
action; in that case, the request will go straight to the finalize
stage, without processing further actions.
=head4 URL Path Handling
-You can pass variable arguments as part of the URL path. In this case,
-you must use regex action keys with '^' and '$' anchors, and the
-arguments must be separated with forward slashes (/) in the URL. For
-example, suppose you want to handle C</foo/$bar/$baz>, where C<$bar> and
-C<$baz> may vary:
+You can pass variable arguments as part of the URL path, separated with
+forward slashes (/). If the action is a Regex or LocalRegex, the '$' anchor
+must be used. For example, suppose you want to handle C</foo/$bar/$baz>,
+where C<$bar> and C<$baz> may vary:
sub foo : Regex('^foo$') { my ($self, $context, $bar, $baz) = @_; }
So Catalyst would never mistakenly dispatch the first two URLs to the
'^foo$' action.
+If a Regex or LocalRegex action doesn't use the '$' anchor, the action will
+still match a URL containing arguments, however the arguments won't be
+available via C<@_>.
+
=head4 Parameter Processing
Parameters passed in the URL query string are handled with methods in
sub show_message : Private {
my ( $self, $c ) = @_;
- $c->res->output( $c->stash->{message} );
+ $c->res->body( $c->stash->{message} );
}
-A C<forward> does not create a new request, so your request
-object (C<$c-E<gt>req>) will remain unchanged. This is a
-key difference between using C<forward> and issuing a
-redirect.
+A C<forward> does not create a new request, so your request object
+(C<$c-E<gt>req>) will remain unchanged. This is a key difference between
+using C<forward> and issuing a redirect.
You can pass new arguments to a C<forward> by adding them
in an anonymous array. In this case C<$c-E<gt>req-E<gt>args>
sub check_message : Private {
my ( $self, $c ) = @_;
- my $first_argument = $c->req->args[0]; # now = 'test1'
+ my $first_argument = $c->req->args->[0]; # now = 'test1'
# do something...
}
-
+
As you can see from these examples, you can just use the method name as
long as you are referring to methods in the same controller. If you want
to forward to a method in another controller, or the main application,
sub hello : Global {
my ( $self, $c ) = @_;
- $c->forward(qw/MyApp::M::Hello say_hello/);
+ $c->forward(qw/MyApp::Model::Hello say_hello/);
}
sub bye : Global {
my ( $self, $c ) = @_;
- $c->forward('MyApp::M::Hello'); # no method: will try 'process'
+ $c->forward('MyApp::Model::Hello'); # no method: will try 'process'
}
- package MyApp::M::Hello;
+ package MyApp::Model::Hello;
sub say_hello {
my ( $self, $c ) = @_;
- $c->res->output('Hello World!');
+ $c->res->body('Hello World!');
}
sub process {
my ( $self, $c ) = @_;
- $c->res->output('Goodbye World!');
+ $c->res->body('Goodbye World!');
}
Note that C<forward> returns to the calling action and continues
Catalyst will automatically try to call process() if you omit the
method.
-=head3 Components
-
-Catalyst has an uncommonly flexible component system. You can define as many
-L<Models>, L<Views>, and L<Controllers> as you like.
-
-All components must inherit from L<Catalyst::Base>, which provides a simple
-class structure and some common class methods like C<config> and C<new>
-(constructor).
-
- package MyApp::C::Catalog;
-
- use strict;
- use base 'Catalyst::Base';
-
- __PACKAGE__->config( foo => 'bar' );
-
- 1;
-
-You don't have to C<use> or otherwise register Models, Views, and
-Controllers. Catalyst automatically discovers and instantiates them
-when you call C<setup> in the main application. All you need to do is
-put them in directories named for each Component type. Notice that you
-can use some very terse aliases for each one.
-
-=over 4
-
-=item * B<MyApp/Model/>
-
-=item * B<MyApp/M/>
-
-=item * B<MyApp/View/>
-
-=item * B<MyApp/V/>
-
-=item * B<MyApp/Controller/>
-
-=item * B<MyApp/C/>
-
-=back
-
-=head4 Views
-
-To show how to define views, we'll use an already-existing base class for the
-L<Template Toolkit|Template>, L<Catalyst::View::TT>. All we need to do is
-inherit from this class:
-
- package MyApp::V::TT;
-
- use strict;
- use base 'Catalyst::View::TT';
-
- 1;
-
-(You can also generate this automatically by using the helper script:
-
- script/myapp_create.pl view TT TT
-
-where the first C<TT> tells the script that the name of the view should
-be C<TT>, and the second that it should be a Template Toolkit view.)
-
-This gives us a process() method and we can now just do
-$c->forward('MyApp::V::TT') to render our templates. The base class makes
-process() implicit, so we don't have to say C<$c-E<gt>forward(qw/MyApp::V::TT
-process/)>.
-
- sub hello : Global {
- my ( $self, $c ) = @_;
- $c->stash->{template} = 'hello.tt';
- }
-
- sub end : Private {
- my ( $self, $c ) = @_;
- $c->forward('MyApp::V::TT');
- }
-
-You normally render templates at the end of a request, so it's a perfect
-use for the global C<end> action.
-
-Also, be sure to put the template under the directory specified in
-C<$c-E<gt>config-E<gt>{root}>, or you'll be forced to look at our
-eyecandy debug screen. ;)
-
-=head4 Models
-
-To show how to define models, again we'll use an already-existing base class,
-this time for L<Class::DBI>: L<Catalyst::Model::CDBI>.
-
-But first, we need a database.
-
- -- myapp.sql
- CREATE TABLE foo (
- id INTEGER PRIMARY KEY,
- data TEXT
- );
-
- CREATE TABLE bar (
- id INTEGER PRIMARY KEY,
- foo INTEGER REFERENCES foo,
- data TEXT
- );
-
- INSERT INTO foo (data) VALUES ('TEST!');
-
-
- % sqlite /tmp/myapp.db < myapp.sql
-
-Now we can create a CDBI component for this database.
-
- package MyApp::M::CDBI;
-
- use strict;
- use base 'Catalyst::Model::CDBI';
-
- __PACKAGE__->config(
- dsn => 'dbi:SQLite:/tmp/myapp.db',
- relationships => 1
- );
-
- 1;
-
-Catalyst automatically loads table layouts and relationships. Use the stash to
-pass data to your templates.
-
- package MyApp;
-
- use strict;
- use Catalyst '-Debug';
-
- __PACKAGE__->config(
- name => 'My Application',
- root => '/home/joeuser/myapp/root'
- );
-
- __PACKAGE__->setup;
-
- sub end : Private {
- my ( $self, $c ) = @_;
- $c->stash->{template} ||= 'index.tt';
- $c->forward('MyApp::V::TT');
- }
- sub view : Global {
- my ( $self, $c, $id ) = @_;
- $c->stash->{item} = MyApp::M::CDBI::Foo->retrieve($id);
- }
-
- 1;
-
- # Then, in a TT template:
- The id is [% item.data %]
-
-Models do not have to be part of your Catalyst application; you
-can always call an outside module that serves as your Model:
-
- # in a Controller
- sub list : Local {
- my ( $self, $c ) = @_;
- $c->stash->{template} = 'list.tt';
- use Some::Outside::CDBI::Module;
- my @records = Some::Outside::CDBI::Module->retrieve_all;
- $c->stash->{records} = \@records;
- }
-
-But by using a Model that is part of your Catalyst application, you gain
-several things: you don't have to C<use> each component, Catalyst will
-find and load it automatically at compile-time; you can C<forward> to
-the module, which can only be done to Catalyst components; and only
-Catalyst components can be fetched with
-C<$c-E<gt>comp('MyApp::M::SomeModel')>.
-
-Happily, since many people have existing Model classes that they
-would like to use with Catalyst (or, conversely, they want to
-write Catalyst models that can be used outside of Catalyst, e.g.
-in a cron job), it's trivial to write a simple component in
-Catalyst that slurps in an outside Model:
-
- package MyApp::M::Catalog;
- use base qw/Catalyst::Base Some::Other::CDBI::Module::Catalog/;
- 1;
-
-and that's it! Now C<Some::Other::CDBI::Module::Catalog> is part of your
-Cat app as C<MyApp::M::Catalog>.
+=head3 Testing
-=head4 Controllers
+Catalyst has a built-in http server for testing or local
+deployment. (Later, you can easily use a more powerful server, for
+example Apache/mod_perl or FastCGI, in a production environment.)
-Multiple controllers are a good way to separate logical domains of your
-application.
+Start your application on the command line...
- package MyApp::C::Login;
+ script/myapp_server.pl
- sub sign-in : Local { }
- sub new-password : Local { }
- sub sign-out : Local { }
+...then visit http://localhost:3000/ in a browser to view the output.
- package MyApp::C::Catalog;
+You can also do it all from the command line:
- sub view : Local { }
- sub list : Local { }
+ script/myapp_test.pl http://localhost/
- package MyApp::C::Cart;
+Catalyst has a number of tools for actual regression testing of
+applications. The helper scripts will automatically generate basic tests
+that can be extended as you develop your project. To write your own
+comprehensive test scripts, L<Test::WWW::Mechanize::Catalyst> is an
+invaluable tool.
- sub add : Local { }
- sub update : Local { }
- sub order : Local { }
-
-=head3 Testing
+For more testing ideas, see L<Catalyst::Manual::Tutorial::Testing>.
-Catalyst has a built-in http server for testing! (Later, you can easily use a
-more powerful server, e.g. Apache/mod_perl, in a production environment.)
+Have fun!
-Start your application on the command line...
+=head1 SEE ALSO
- script/myapp_server.pl
+=over 4
-...then visit http://localhost:3000/ in a browser to view the output.
+=item * L<Catalyst::Manual::About>
-You can also do it all from the command line:
+=item * L<Catalyst::Manual::Tutorial>
- script/myapp_test.pl http://localhost/
+=item * L<Catalyst>
-Have fun!
+=back
=head1 SUPPORT
IRC:
Join #catalyst on irc.perl.org.
+ Join #catalyst-dev on irc.perl.org to help with development.
-Mailing-lists:
+Mailing lists:
http://lists.rawmode.org/mailman/listinfo/catalyst
http://lists.rawmode.org/mailman/listinfo/catalyst-dev
Marcus Ramberg, C<mramberg@cpan.org>
Jesse Sheidlower, C<jester@panix.com>
Danijel Milicevic, C<me@danijel.de>
+Kieren Diment, C<kd@totaldatasolution.com>
+Yuval Kogman, C<nothingmuch@woobling.org>
=head1 COPYRIGHT
-This program is free software, you can redistribute it and/or modify it under
-the same terms as Perl itself.
+This program is free software. You can redistribute it and/or modify it
+under the same terms as Perl itself.
projects / catagits/Catalyst-Runtime.git / blobdiff