=head1 DESCRIPTION
-This is a brief overview of why and how to use Catalyst. It explains how Catalyst works and shows how to quickly get a simple application up and running.
+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.
=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.
=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 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 M, V, and C map to those concerns, with examples of
+well-known Perl modules you may want to use for each.
=over 4
=item * B<View>
-Present content to the user. L<Template Toolkit|Template>, L<Mason|HTML::Mason>...
+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 the whole request phase, check parameters, dispatch actions, flow
+control. Catalyst!
=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, Johson and Vlissides, a.k.a. the Gang of Four (GoF). Or just search the web. Many, many web application frameworks follow 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). You
+can also just Google it. Many, many web application frameworks are
+based on MVC, including all those listed above.
=head3 Flexibility
-Catalyst is much more flexible than many other frameworks.
+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.
=over 4
-=item * B<Multiple Models, Views and Controllers>
+=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 is very flexible about these Components. 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, plus 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<Re-Useable Components>
+=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 via regular expressions! Unlike some 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:
- MyApp->action( 'hello' => sub {
+ sub hello : Global {
my ( $self, $context ) = @_;
- $context->response->output('Hello World!');
- });
+ $context->response->body('Hello World!');
+ }
Now http://localhost:3000/hello prints "Hello World!".
=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 in 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.
+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::CDBI> for L<Class::DBI>, or L<Catalyst::View::TT>
+for L<Template Toolkit|Template>.
-=item * B<Builtin Test Framework>
+=item * B<Built-in Test Framework>
-Catalyst comes with a builtin, 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 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. 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'
+ $ perl -MCPAN -e 'install Task::Catalyst'
=head3 Setup
- $ catalyst.pl My::App
- $ cd My-App
- $ script/create.pl controller My::Controller
+ $ catalyst.pl MyApp
+ # output omitted
+ $ cd MyApp
+ $ script/myapp_create.pl controller Library::Login
=head3 Run
- $ script/server.pl
+ $ script/myapp_server.pl
-Now visit these locations with your favorite browser or user agent to see Catalyst in action:
+Now visit these locations with your favorite browser or user agent to see
+Catalyst in action:
=over 4
=item http://localhost:3000/
-=item http://localhost:3000/my_controller/
+=item http://localhost:3000/library/login/
=back
=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 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, define application-wide
+actions, and extend Catalyst.
package MyApp;
MyApp->config(
name => 'My Application',
- root => '/home/joeuser/myapp/root',
- # You can put whatever you want in here:
- # my_param_name => $my_param_value,
+ # You can put anything else you want in here:
+ my_configuration_variable => 'something',
);
- MyApp->action( '!default' => sub {
+ sub default : Private {
my ( $self, $context ) = @_;
- $context->response->output('Catalyst rockz!');
- });
+ $context->response->body('Catalyst rocks!');
+ }
1;
-For most applications, Catalyst requires you to define only two config parameters:
+For most applications, Catalyst requires you to define only one config
+parameter:
=over 4
Name of your application.
-=item * B<root>
-
-Path to additional files like templates, images or other static data.
-
=back
-However, you can define as many parameters as you want for plugins or whatever you need. You can access them anywhere in your application via C<$context-E<gt>config-E<gt>{$param_name}>.
+Optionally, you can specify a B<root> parameter for templates and static
+data. If omitted, Catalyst will try to auto-detect the directory's
+location. You can define as many parameters as you want for plugins or
+whatever you need. You can access them anywhere in your application via
+C<$context-E<gt>config-E<gt>{$param_name}>.
=head3 Context
-Catalyst automatically blesses a Context object into your application class and makes it available everywhere in your application. Use the Context to directly interact with Catalyst and glue your L<Components> together.
+Catalyst automatically blesses a Context object into your application
+class and makes it available everywhere in your application. Use the
+Context to directly interact with Catalyst and glue your L<Components>
+together. For example, if you need to use the Context from within a
+Template Toolkit template, it's already there:
+
+ <h1>Welcome to [% c.config.name %]!</h1>
-As illustrated earlier in our URL-to-Action dispatching example, the Context is always the second method parameter, behind the Component object reference or class name itself. Previously we called it C<$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>:
- MyApp->action( 'hello' => sub {
+ sub hello : Global {
my ( $self, $c ) = @_;
- $c->res->output('Hello World!');
- });
+ $c->res->body('Hello World!');
+ }
The Context contains several important objects:
$c->request
$c->req # alias
-The request contains all kinds of request-specific information, like query parameters, cookies, uploads, headers and more.
+The request object contains all kinds of request-specific information, like
+query parameters, cookies, uploads, headers, and more.
$c->req->params->{foo};
$c->req->cookies->{sessionid};
$c->response
$c->res # alias
-The response is like the request, but contains just response-specific information.
+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 * B<Stash>
$c->stash
-
$c->stash->{foo} = 'bar';
=back
-The last of these, the stash, is a universal hash for sharing data among application components. For an example, we return to our 'hello' action:
-
- MyApp->action(
+The last of these, the stash, is a universal hash for sharing data among
+application components. For an example, we return to our 'hello' action:
- 'hello' => sub {
- my ( $self, $c ) = @_;
- $c->stash->{message} = 'Hello World!';
- $c->forward('!show-message');
- },
+ sub hello : Global {
+ my ( $self, $c ) = @_;
+ $c->stash->{message} = 'Hello World!';
+ $c->forward('show_message');
+ }
- '!show-message' => sub {
- my ( $self, $c ) = @_;
- $c->res->output( $c->stash->{message} );
- },
+ sub show_message : Private {
+ my ( $self, $c ) = @_;
+ $c->res->body( $c->stash->{message} );
+ }
- );
+Note that the stash should be used only for passing data in an
+individual request cycle; it gets cleared at a new request. If you need
+to maintain more persistent data, use a session.
=head3 Actions
-To define a Catalyst action, register it into your application with the C<action> method. C<action> accepts a key-value pair, where the key represents one or more URLs or application states and the value is a code reference, the action to execute in reponse to the URL(s) or application state(s).
+A Catalyst controller is defined by its actions. An action is a sub with
+a special attribute. You've already seen some examples of actions in
+this document. The URL (for example http://localhost.3000/foo/bar)
+consists of two parts, the base (http://localhost:3000/ in this example)
+and the path (foo/bar). Please note that the trailing slash after the
+hostname[:port] always belongs to base and not to the action.
-Catalyst supports several ways to define Actions:
+Catalyst supports several types of actions:
=over 4
=item * B<Literal>
- MyApp->action( 'foo/bar' => sub { } );
+ package MyApp::Controller::My::Controller;
+ sub bar : Path('foo/bar') { }
+
+Literal C<Path> actions will act relative to their current
+namespace. The above example matches only
+http://localhost:3000/my/controller/foo/bar. If you start your path with
+a forward slash, it will match from the root. Example:
+
+ package MyApp::Controller::My::Controller;
+ sub bar : Path('/foo/bar') { }
Matches only http://localhost:3000/foo/bar.
+ package MyApp::Controller::My::Controller;
+ sub bar : Path { }
+
+By leaving the C<Path> definition empty, it will match on the namespace
+root. The above code matches http://localhost:3000/my/controller.
+
=item * B<Regex>
- MyApp->action( '/^foo(\d+)/bar(\d+)$/' => sub { } );
+ sub bar : Regex('^item(\d+)/order(\d+)$') { }
+
+Matches any URL that matches the pattern in the action key, e.g.
+http://localhost:3000/item23/order42. The '' around the regexp is
+optional, but perltidy likes it. :)
+
+Regex matches act globally, i.e. without reference to the namespace from
+which it is called, so that a C<bar> method in the
+C<MyApp::Controller::Catalog::Order::Process> namespace won't match any
+form of C<bar>, C<Catalog>, C<Order>, or C<Process> unless you
+explicitly put this in the regex. To achieve the above, you should
+consider using a C<LocalRegex> action.
+
+=item * B<LocalRegex>
+
+ sub bar : LocalRegex('^widget(\d+)$') { }
+
+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.
-Matches any URL that matches the pattern in the action key, e.g. http://localhost:3000/foo23/bar42. The pattern must be enclosed with forward slashes, i.e. '/$pattern/'.
+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.
-If you use capturing parantheses to extract values within the matching URL (23, 42 in the above example), those values are available in the $c->req->snippets array. If you want to pass arguments at the end of your URL, you must use regex action keys. See L</URL Argument Handling> below.
+ package MyApp::Controller::Catalog;
+ sub bar : LocalRegex('widget(\d+)$') { }
+
+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<$c-E<gt>req-E<gt>snippets> array. In the above example, "widget23"
+would capture "23" in the above example, and
+C<$c-E<gt>req-E<gt>snippets-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>
+
+ package MyApp;
+ sub foo : Global { }
+
+Matches http://localhost:3000/foo. The function name is mapped directly
+to the application base.
=item * B<Namespace-Prefixed>
package MyApp::Controller::My::Controller;
- MyApp->action( '?foo' => sub { } );
+ sub foo : Local { }
-Matches http://localhost:3000/my_controller/foo. The action key must be prefixed with '?'.
+Matches http://localhost:3000/my/controller/foo.
-Prefixing the action key with '?' 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::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.
+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::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<Private>
- MyApp->action( '!foo' => sub { } );
+ 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');
+ $c->forward('foo');
-See L</Flow Control> for a full explanation of C<forward>.
+See L</Flow Control> for a full explanation of C<forward>. Note that, as
+discussed there, when forwarding from another component, you must use
+the absolute path to the method, so that a private C<bar> method in your
+C<MyApp::Controller::Catalog::Order::Process> controller must, if called
+from elsewhere, be reached with
+C<$c-E<gt>forward('/catalog/order/process/bar')>.
=back
-=head4 Builtin Private Actions
+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.
+
+=head4 Built-in Private Actions
-In response to specific application states, Catalyst will automatically call these built in private actions:
+In response to specific application states, Catalyst will automatically
+call these built-in private actions in your application class:
=over 4
-=item * B<!default>
+=item * B<default : Private>
-Called when no other action matches.
+Called when no other action matches. Could be used, for example, for
+displaying a generic frontpage for the main app, or an error page for
+individual controllers.
-=item * B<!begin>
+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.
-Called at the beginning of a request, before any matching actions are called.
+=item * B<index : Private>
-=item * B<!end>
+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.
-=back
+=item * B<begin : Private>
+
+Called at the beginning of a request, before any matching actions are
+called.
+
+=item * B<end : Private>
Called at the end of a request, after all matching actions are called.
-=head4 B<Namespace-Prefixed Private Actions>
+=back
+
+=head4 Built-in actions in controllers/autochaining
+
+ Package MyApp::Controller::Foo;
+ sub begin : Private { }
+ sub default : Private { }
+ sub auto : Private { }
+
+You can define built-in private actions within your controllers as
+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::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.
+
+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
+C<begin>, but before your action is processed. Unlike the other
+built-ins, C<auto> actions I<do not> override each other; they will be
+called in turn, starting with the application class and going through to
+the I<most> specific class. I<This is the reverse of the order in which
+the normal built-ins override each other>.
+
+Here are some examples of the order in which the various built-ins
+would be called:
+
+=over 4
+
+=item for a request for C</foo/foo>
+
+ MyApp::begin
+ MyApp::auto
+ MyApp::Controller::Foo::default # in the absence of MyApp::Controller::Foo::Foo
+ MyApp::end
+
+=item for a request for C</foo/bar/foo>
+
+ MyApp::Controller::Foo::Bar::begin
+ MyApp::auto
+ 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
+
+The C<auto> action is also distinguished by the fact that you can break
+out of the processing chain by returning 0. If an C<auto> action returns
+0, any remaining actions will be skipped, except for C<end>. So, for the
+request above, if the first auto returns false, the chain would look
+like this:
+
+=over 4
+
+=item for a request for C</foo/bar/foo> where first C<auto> returns
+false
- MyApp->action( '!?foo' => sub { } );
- MyApp->action( '!?default' => sub { } );
+ MyApp::Controller::Foo::Bar::begin
+ MyApp::auto
+ MyApp::Controller::Foo::Bar::end
-The leading '!?' indicates that these are namespace-prefixed private actions. These override any application-wide private actions with the same names, and can be called only from within the namespace in which they are defined. Any private action can be namespace-prefixed, including the builtins. One use for this might be to give a Controller its own !?default, !?begin and !?end.
+=back
+
+An example of why one might use this is an authentication action: you
+could set up a C<auto> action to handle authentication in your
+application class (which will always be called first), and if
+authentication fails, returning 0 would skip any remaining methods
+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
+action; in that case, the request will go straight to the finalize
+stage, without processing further actions.
-=head4 B<URL Argument Handling>
+=head4 URL Path Handling
-If you want to pass variable arguments at the end of a URL, you must use regex actions keys with '^' and '$' anchors, and the arguments must be separated with forward slashes (/) in the URL. For example, suppose you want to handle /foo/$bar/$baz, where $bar and $baz may vary:
+You can pass variable arguments as part of the URL path. In this case,
+you must use regex action keys with '^' and '$' 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:
- MyApp->action( '/^foo$/' => sub { my ($self, $context, $bar, $baz) = @_; } );
+ sub foo : Regex('^foo$') { my ($self, $context, $bar, $baz) = @_; }
-But what if you also defined actions for /foo/boo and /foo/boo/hoo ?
+But what if you also defined actions for C</foo/boo> and C</foo/boo/hoo>?
- MyApp->action( '/foo/boo' => sub { .. } );
- MyApp->action( '/foo/boo/hoo' => sub { .. } );
+ sub boo : Path('foo/boo') { .. }
+ sub hoo : Path('foo/boo/hoo') { .. }
Catalyst matches actions in most specific to least specific order:
/foo/boo/hoo
/foo/boo
- /foo # might be /foo/bar/baz
+ /foo # might be /foo/bar/baz but won't be /foo/boo/hoo
+
+So Catalyst would never mistakenly dispatch the first two URLs to the
+'^foo$' action.
+
+=head4 Parameter Processing
+
+Parameters passed in the URL query string are handled with methods in
+the L<Catalyst::Request> class. The C<param> method is functionally
+equivalent to the C<param> method of C<CGI.pm> and can be used in
+modules that require this.
-So Catalyst would never mistakenly dispatch the first two URLs to the '/^foo$/' action.
+ # http://localhost:3000/catalog/view/?category=hardware&page=3
+ my $category = $c->req->param('category');
+ my $current_page = $c->req->param('page') || 1;
+
+ # multiple values for single parameter name
+ my @values = $c->req->param('scrolling_list');
+
+ # DFV requires a CGI.pm-like input hash
+ my $results = Data::FormValidator->check($c->req->params, \%dfv_profile);
=head3 Flow Control
-Control the application flow with the C<forward> method, which accepts the key of an action to execute.
+You control the application flow with the C<forward> method, which
+accepts the key of an action to execute. This can be an action in the
+same or another Catalyst controller, or a Class name, optionally
+followed by a method name. After a C<forward>, the control flow will
+return to the method from which the C<forward> was issued.
- MyApp->action(
+A C<forward> is similar to a method call. The main differences are that
+it wraps the call in an C<eval> to allow exception handling; it
+automatically passes along the context object (C<$c> or C<$context>);
+and it allows profiling of each call (displayed in the log with
+debugging enabled).
- 'hello' => sub {
- my ( $self, $c ) = @_;
- $c->stash->{message} = 'Hello World!';
- $c->forward('!check-message');
- },
+ sub hello : Global {
+ my ( $self, $c ) = @_;
+ $c->stash->{message} = 'Hello World!';
+ $c->forward('check_message'); # $c is automatically included
+ }
- '!check-message' => sub {
- my ( $self, $c ) = @_;
- return unless $c->stash->{message};
- $c->forward('!show-message');
- },
+ sub check_message : Private {
+ my ( $self, $c ) = @_;
+ return unless $c->stash->{message};
+ $c->forward('show_message');
+ }
- '!show-message' => sub {
- my ( $self, $c ) = @_;
- $c->res->output( $c->stash->{message} );
- },
+ sub show_message : Private {
+ my ( $self, $c ) = @_;
+ $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.
-You can also forward to classes and methods.
+You can pass new arguments to a C<forward> by adding them
+in an anonymous array. In this case C<$c-E<gt>req-E<gt>args>
+will be changed for the duration of the C<forward> only; upon
+return, the original value of C<$c-E<gt>req-E<gt>args> will
+be reset.
- MyApp->action(
+ sub hello : Global {
+ my ( $self, $c ) = @_;
+ $c->stash->{message} = 'Hello World!';
+ $c->forward('check_message',[qw/test1/]);
+ # now $c->req->args is back to what it was before
+ }
- 'hello' => sub {
- my ( $self, $c ) = @_;
- $c->forward(qw/MyApp::M::Hello say_hello/);
- },
+ sub check_message : Private {
+ my ( $self, $c ) = @_;
+ 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,
+you will have to refer to the method by absolute path.
- 'bye' => sub {
- my ( $self, $c ) = @_;
- $c->forward('MyApp::M::Hello');
- },
+ $c->forward('/my/controller/action');
+ $c->forward('/default'); # calls default in main application
- );
+Here are some examples of how to forward to classes and methods.
- package MyApp::M::Hello;
+ sub hello : Global {
+ my ( $self, $c ) = @_;
+ $c->forward(qw/MyApp::Model::Hello say_hello/);
+ }
+
+ sub bye : Global {
+ my ( $self, $c ) = @_;
+ $c->forward('MyApp::Model::Hello'); # no method: will try 'process'
+ }
+
+ 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 after processing.
-Catalyst will automatically try to call process() if you omit the method.
+Note that C<forward> returns to the calling action and continues
+processing after the action finishes. If you want all further processing
+in the calling action to stop, use C<detach> instead, which will execute
+the C<detach>ed action and not return to the calling sub. In both cases,
+Catalyst will automatically try to call process() if you omit the
+method.
=head3 Components
-Again, Catalyst has an uncommonly flexible component system. You can define as many L<Models>, L<Views> and L<Controllers> as you like.
+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).
+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::MyController;
+ package MyApp::Controller::Catalog;
use strict;
use base 'Catalyst::Base';
1;
-You don't have to C<use> or otherwise register Models, Views and Controllers. Catalyst automatically discovers and instantiates them, at startup. 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.
+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
=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:
+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;
+ package MyApp::View::TT;
use strict;
use base 'Catalyst::View::TT';
1;
-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/)>.
+(You can also generate this automatically by using the helper script:
- MyApp->action(
+ script/myapp_create.pl view TT TT
- 'hello' => sub {
- my ( $self, $c ) = @_;
- $c->stash->{template} = 'hello.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.)
- '!end' => sub {
- my ( $self, $c ) = @_;
- $c->forward('MyApp::View::TT');
- },
+This gives us a process() method and we can now just do
+$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';
+ }
-You normally render templates at the end of a request, so it's a perfect use for the !end action.
+ sub end : Private {
+ my ( $self, $c ) = @_;
+ $c->forward('MyApp::View::TT');
+ }
+
+You normally render templates at the end of a request, so it's a perfect
+use for the global C<end> action.
-Also, be sure to put the template under the directory specified in C<$c-E<gt>config->{root}>, or you'll be forced to look at our eyecandy debug screen. ;)
+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>.
+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.
Now we can create a CDBI component for this database.
- package MyApp::M::CDBI;
+ package MyApp::Model::CDBI;
use strict;
use base 'Catalyst::Model::CDBI';
1;
-Catalyst automatically loads table layouts and relationships. Use the stash to pass data to your templates.
+Catalyst automatically loads table layouts and relationships. Use the
+stash to pass data to your templates.
package MyApp;
name => 'My Application',
root => '/home/joeuser/myapp/root'
);
+
+ __PACKAGE__->setup;
+
+ sub end : Private {
+ my ( $self, $c ) = @_;
+ $c->stash->{template} ||= 'index.tt';
+ $c->forward('MyApp::View::TT');
+ }
- __PACKAGE__->action(
+ sub view : Global {
+ my ( $self, $c, $id ) = @_;
+ $c->stash->{item} = MyApp::Model::CDBI::Foo->retrieve($id);
+ }
- '!end' => sub {
- my ( $self, $c ) = @_;
- $c->stash->{template} ||= 'index.tt';
- $c->forward('MyApp::V::TT');
- },
+ 1;
- 'view' => sub {
- my ( $self, $c, $id ) = @_;
- $c->stash->{item} = MyApp::M::CDBI::Foo->retrieve($id);
- }
+ # 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>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::Catalog;
+ use base qw/Catalyst::Base Some::Other::CDBI::Module::Catalog/;
1;
- The id is [% item.data %]
+and that's it! Now C<Some::Other::CDBI::Module::Catalog> is part of your
+Cat app as C<MyApp::Model::Catalog>.
=head4 Controllers
-Multiple Controllers are a good way to separate logical domains of your application.
+Multiple controllers are a good way to separate logical domains of your
+application.
- package MyApp::C::Login;
+ package MyApp::Controller::Login;
- MyApp->action(
- '?sign-in' => sub { },
- '?new-password' => sub { },
- '?sign-out' => sub { },
- );
+ sub sign-in : Local { }
+ sub new-password : Local { }
+ sub sign-out : Local { }
- package MyApp::C::Catalog;
+ package MyApp::Controller::Catalog;
- MyApp->action(
- '?view' => sub { },
- '?list' => sub { },
- );
+ sub view : Local { }
+ sub list : Local { }
- package MyApp::C::Cart;
+ package MyApp::Controller::Cart;
- MyApp->action(
- '?add' => sub { },
- '?update' => sub { },
- '?order' => sub { },
- );
+ sub add : Local { }
+ sub update : Local { }
+ sub order : Local { }
=head3 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).
+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.)
Start your application on the command line...
- script/server.pl
+ script/myapp_server.pl
...then visit http://localhost:3000/ in a browser to view the output.
You can also do it all from the command line:
- script/test.pl http://localhost/
+ script/myapp_test.pl http://localhost/
Have fun!
Join #catalyst on irc.perl.org.
-Mailing-Lists:
+Mailing-lists:
http://lists.rawmode.org/mailman/listinfo/catalyst
http://lists.rawmode.org/mailman/listinfo/catalyst-dev
=head1 AUTHOR
-Sebastian Riedel, C<sri@oook.de> and David Naughton, C<naughton@umn.edu>
+Sebastian Riedel, C<sri@oook.de>
+David Naughton, C<naughton@umn.edu>
+Marcus Ramberg, C<mramberg@cpan.org>
+Jesse Sheidlower, C<jester@panix.com>
+Danijel Milicevic, C<me@danijel.de>
=head1 COPYRIGHT
projects / catagits/Catalyst-Runtime.git / blobdiff