Catalyst - The Elegant MVC Web Application Framework

    # use the helper to start a new application
    catalyst.pl MyApp

    # add models, views, controllers
    script/myapp_create.pl model Database DBIC dbi:SQLite:/path/to/db
    script/myapp_create.pl view TT TT
    script/myapp_create.pl controller Search

    # built in testserver -- use -r to restart automatically on changes
    script/myapp_server.pl

    # command line testing interface
    script/myapp_test.pl /yada

    ### in MyApp.pm
    use Catalyst qw/-Debug/; # include plugins here as well

    sub foo : Global { # called for /foo, /foo/1, /foo/1/2, etc.
        my ( $self, $c, @args ) = @_; # args are qw/1 2/ for /foo/1/2
        $c->stash->{template} = 'foo.tt'; # set the template
        # lookup something from db -- stash vars are passed to TT
        $c->stash->{data} = 
          MyApp::Model::Database::Foo->search( { country => $args[0] } );
        if ( $c->req->params->{bar} ) { # access GET or POST parameters
            $c->forward( 'bar' ); # process another action
            # do something else after forward returns            
        }
    }

    # The foo.tt TT template can use the stash data from the database
    [% WHILE (item = data.next) %]
        [% item.foo %]
    [% END %]

    # called for /bar/of/soap, /bar/of/soap/10, etc.
    sub bar : Path('/bar/of/soap') { ... }

    # called for all actions, from the top-most controller downwards
    sub auto : Private { 
        my ( $self, $c ) = @_;
        if ( !$c->user ) {
            $c->res->redirect( '/login' ); # require login
            return 0; # abort request and go immediately to end()
        }
        return 1; # success; carry on to next action
    }

    # called after all actions are finished
    sub end : Private { 
        my ( $self, $c ) = @_;
        if ( scalar @{ $c->error } ) { ... } # handle errors
        return if $c->res->body; # already have a response
        $c->forward( 'MyApp::View::TT' ); # render template
    }

    ### in MyApp/Controller/Foo.pm
    # called for /foo/bar
    sub bar : Local { ... }

    # called for /blargle
    sub blargle : Global { ... }

    # an index action matches /foo, but not /foo/1, etc.
    sub index : Private { ... }

    ### in MyApp/Controller/Foo/Bar.pm
    # called for /foo/bar/baz
    sub baz : Local { ... }

    # first MyApp auto is called, then Foo auto, then this
    sub auto : Private { ... }

    # powerful regular expression paths are also possible
    sub details : Regex('^product/(\w+)/details$') {
        my ( $self, $c ) = @_;
        # extract the (\w+) from the URI
        my $product = $c->req->snippets->[0];
    }

See Catalyst::Manual::Intro for additional information.

The key concept of Catalyst is DRY (Don't Repeat Yourself).

See Catalyst::Manual for more documentation.

Catalyst plugins can be loaded by naming them as arguments to the use Catalyst statement. Omit the CWCatalyst::Plugin:: prefix from the plugin name, i.e., CWCatalyst::Plugin::My::Module becomes CWMy::Module.

    use Catalyst qw/My::Module/;

Special flags like CW-Debug and CW-Engine can also be specified as arguments when Catalyst is loaded:

    use Catalyst qw/-Debug My::Module/;

The position of plugins and flags in the chain is important, because they are loaded in exactly the order in which they appear.

The following flags are supported:

Enables debug output.

Forces Catalyst to use a specific engine. Omit the CWCatalyst::Engine:: prefix of the engine name, i.e.:

    use Catalyst qw/-Engine=CGI/;

Forces Catalyst to use a specific home directory, e.g.:

    use Catalyst qw[-Home=/usr/sri];

Specifies log level.

Returns a Catalyst::Action object for the current action, which stringifies to the action name. See Catalyst::Action.

Returns the namespace of the current action, i.e., the uri prefix corresponding to the controller of the current action. For example:

    # in Controller::Foo::Bar
    $c->namespace; # returns 'foo/bar';

Returns the current Catalyst::Request object. See Catalyst::Request.

Forwards processing to a private action. If you give a class name but no method, CWprocess() is called. You may also optionally pass arguments in an arrayref. The action will receive the arguments in CW@_ and CW$c->req->args. Upon returning from the function, CW$c->req->args will be restored to the previous values.

    $c->forward('/foo');
    $c->forward('index');
    $c->forward(qw/MyApp::Model::CDBI::Foo do_stuff/);
    $c->forward('MyApp::View::TT');

Returns an arrayref containing error messages. If Catalyst encounters an error while processing a request, it stores the error in CW$c->error. This method should not be used to store non-fatal error messages.

    my @error = @{ $c->error };

Add a new error.

    $c->error('Something bad happened');

Clear errors. You probably don't want to clear the errors unless you are implementing a custom error screen.

    $c->error(0);

Returns the current Catalyst::Response object.

Returns a hashref to the stash, which may be used to store data and pass it between components during a request. You can also set hash keys by passing arguments. The stash is automatically sent to the view. The stash is cleared at the end of a request; it cannot be used for persistent storage.

    $c->stash->{foo} = $bar;
    $c->stash( { moose => 'majestic', qux => 0 } );
    $c->stash( bar => 1, gorch => 2 ); # equivalent to passing a hashref

    # stash is automatically passed to the view for use in a template
    $c->forward( 'MyApp::V::TT' );

Contains the return value of the last executed action.

Gets a component object by name. This method is no longer recommended, unless you want to get a specific component by full class. CW$c->controller, CW$c->model, and CW$c->view should be used instead.

Gets a Catalyst::Controller instance by name.

    $c->controller('Foo')->do_stuff;

Gets a Catalyst::Model instance by name.

    $c->model('Foo')->do_stuff;

Gets a Catalyst::View instance by name.

    $c->view('Foo')->do_stuff;

Returns or takes a hashref containing the application's configuration.

    __PACKAGE__->config({ db => 'dsn:SQLite:foo.db' });

Overload to enable debug messages (same as -Debug option).

Returns the dispatcher instance. Stringifies to class name. See Catalyst::Dispatcher.

Returns the engine instance. Stringifies to the class name. See Catalyst::Engine.

Returns the logging object instance. Unless it is already set, Catalyst sets this up with a Catalyst::Log object. To use your own log class:

    $c->log( MyLogger->new );
    $c->log->info( 'Now logging with my own logger!' );

Your log class should implement the methods described in the Catalyst::Log man page.

Merges CW@path with CW$c->config->{home} and returns a Path::Class object.

For example:

    $c->path_to( 'db', 'sqlite.db' );

    MyApp->plugin( 'prototype', 'HTML::Prototype' );

    $c->prototype->define_javascript_functions;

Initializes the dispatcher and engine, loads any plugins, and loads the model, view, and controller components. You may also specify an array of plugins to load here, if you choose to not load them in the CWuse Catalyst line.

    MyApp->setup;
    MyApp->setup( qw/-Debug/ );

Returns the Catalyst welcome HTML page.

These methods are not meant to be used by end users.

Returns a hash of components.

Returns or sets the context class.

Returns a hashref containing coderefs and execution counts (needed for deep recursion detection).

Returns the number of actions on the current internal execution stack.

Dispatches a request to actions.

Returns or sets the dispatcher class.

Returns a list of 2-element array references (name, structure) pairs that will be dumped on the error page in debug mode.

Returns or sets the engine class. Execute a coderef in given class and catch exceptions. Errors are available via CW$c->error.

Finalizes the request.

Finalizes body.

Finalizes cookies.

Finalizes error.

Finalizes headers.

An alias for finalize_body.

Finalizes the input after reading is complete.

Finalizes uploads. Cleans up any temporary files. Gets an action in a given namespace. Gets all actions of a given name in a namespace and all parent namespaces. Called to handle each HTTP request. Creates a Catalyst context from an engine-specific request (Apache, CGI, etc.).

Prepares action.

Prepares message body. Prepares a chunk of data before sending it to HTTP::Body.

Prepares body parameters.

Prepares connection.

Prepares cookies.

Prepares headers.

Prepares parameters.

Prepares path and base.

Prepares query parameters.

Prepares the input for reading.

Prepares the engine request.

Prepares uploads.

Prepares the output for writing.

Returns or sets the request class.

Returns or sets the response class.

Reads a chunk of data from the request body. This method is designed to be used in a while loop, reading CW$maxlength bytes on every call. CW$maxlength defaults to the size of the request if not specified.

You have to set CWMyApp->config->{parse_on_demand} to use this directly.

Starts the engine. Sets an action in a given namespace.

Sets up actions for a component.

Sets up components.

Sets up dispatcher.

Sets up engine.

Sets up the home directory.

Sets up log.

Sets up plugins.

Returns the stack. Writes CW$data to the output stream. When using this method directly, you will need to manually set the CWContent-Length header to the length of your output data, if known.

Returns the Catalyst version number. Mostly useful for powered by messages in template systems.

Catalyst uses internal actions like CW_DISPATCH, CW_BEGIN, CW_AUTO, CW_ACTION, and CW_END. These are by default not shown in the private action table, but you can make them visible with a config parameter.

    MyApp->config->{show_internal_actions} = 1;

By default Catalyst is not case sensitive, so CWMyApp::C::FOO::Bar is mapped to CW/foo/bar. You can activate case sensitivity with a config parameter.

    MyApp->config->{case_sensitive} = 1;

This causes CWMyApp::C::Foo::Bar to map to CW/Foo/Bar.

The request body is usually parsed at the beginning of a request, but if you want to handle input yourself or speed things up a bit, you can enable on-demand parsing with a config parameter.

    MyApp->config->{parse_on_demand} = 1;

Many production servers operate using the common double-server approach, with a lightweight frontend web server passing requests to a larger backend server. An application running on the backend server must deal with two problems: the remote user always appears to be CW127.0.0.1 and the server's hostname will appear to be CWlocalhost regardless of the virtual host that the user connected through.

Catalyst will automatically detect this situation when you are running the frontend and backend servers on the same machine. The following changes are made to the request.

    $c->req->address is set to the user's real IP address, as read from 
    the HTTP X-Forwarded-For header.

    The host value for $c->req->base and $c->req->uri is set to the real
    host, as read from the HTTP X-Forwarded-Host header.

Obviously, your web server must support these headers for this to work.

In a more complex server farm environment where you may have your frontend proxy server(s) on different machines, you will need to set a configuration option to tell Catalyst to read the proxied data from the headers.

    MyApp->config->{using_frontend_proxy} = 1;

If you do not wish to use the proxy support at all, you may set:

    MyApp->config->{ignore_frontend_proxy} = 1;

Catalyst has been tested under Apache 2's threading mpm_worker, mpm_winnt, and the standalone forking HTTP server on Windows. We believe the Catalyst core to be thread-safe.

If you plan to operate in a threaded environment, remember that all other modules you are using must also be thread-safe. Some modules, most notably DBD::SQLite, are not thread-safe.

IRC:

    Join #catalyst on irc.perl.org.

Mailing Lists:

    http://lists.rawmode.org/mailman/listinfo/catalyst
    http://lists.rawmode.org/mailman/listinfo/catalyst-dev

Web:

    http://catalyst.perl.org

Wiki:

    http://dev.catalyst.perl.org

Andy Grundman

Andy Wardley

Andreas Marienborg

Andrew Bramble

Andrew Ford

Andrew Ruthven

Arthur Bergman

Autrijus Tang

Brian Cassidy

Christian Hansen

Christopher Hicks

Dan Sully

Danijel Milicevic

David Kamholz

David Naughton

Drew Taylor

Gary Ashton Jones

Geoff Richards

Jesse Sheidlower

Jesse Vincent

Jody Belka

Johan Lindstrom

Juan Camacho

Leon Brocard

Marcus Ramberg

Matt S Trout

Robert Sedlacek

Sam Vilain

Sascha Kiefer

Tatsuhiko Miyagawa

Ulf Edvinsson

Yuval Kogman

Sebastian Riedel, CWsri@oook.de

This library is free software, you can redistribute it and/or modify it under the same terms as Perl itself.