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Catalyst-5.49_02
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/ Catalyst

NAME

Catalyst - The Elegant MVC Web Application Framework

SYNOPSIS

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

    # add models, views, controllers
    script/myapp_create.pl model Something
    script/myapp_create.pl view Stuff
    script/myapp_create.pl controller Yada

    # built in testserver
    script/myapp_server.pl

    # command line interface
    script/myapp_test.pl /yada


    use Catalyst;

    use Catalyst qw/My::Module My::OtherModule/;

    use Catalyst '-Debug';

    use Catalyst qw/-Debug -Engine=CGI/;

    sub default : Private { $_[1]->res->output('Hello') } );

    sub index : Path('/index.html') {
        my ( $self, $c ) = @_;
        $c->res->output('Hello');
        $c->forward('foo');
    }

    sub product : Regex('^product[_]*(\d*).html$') {
        my ( $self, $c ) = @_;
        $c->stash->{template} = 'product.tt';
        $c->stash->{product} = $c->req->snippets->[0];
    }

See also Catalyst::Manual::Intro

DESCRIPTION

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 Catalyst::Plugin:: prefix from the plugin name, so Catalyst::Plugin::My::Module becomes My::Module.

    use Catalyst 'My::Module';

Special flags like -Debug and -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 that they appear.

The following flags are supported:

-Debug

enables debug output, i.e.:

    use Catalyst '-Debug';

this is equivalent to:

    use Catalyst;
    sub debug { 1 }
-Dispatcher

Force Catalyst to use a specific dispatcher.

-Engine

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

    use Catalyst '-Engine=CGI';
-Home

Force Catalyst to use a specific home directory.

-Log

Specify log level.

METHODS

$c->action

Accessor for the current action

$c->comp($name)
$c->component($name)

Get a component object by name.

    $c->comp('MyApp::Model::MyModel')->do_stuff;
config

Returns a hashref containing your applications settings.

debug

Overload to enable debug messages.

$c->detach( $command [, \@arguments ] )

Like forward but doesn't return.

$c->dispatcher

Contains the dispatcher instance. Stringifies to class.

$c->forward( $command [, \@arguments ] )

Forward processing to a private action or a method from a class. If you define a class without method it will default to process(). also takes an optional arrayref containing arguments to be passed to the new function. $c->req->args will be reset upon returning from the function.

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

Accessor to the namespace of the current action

$c->path_to(@path)

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

For example:

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

Setup.

    $c->setup;
$c->uri_for($path,[@args])

Merges path with $c->request->base for absolute uri's and with $c->request->match for relative uri's, then returns a normalized URI object. If any args are passed, they are added at the end of the path.

$c->error
$c->error($error, ...)
$c->error($arrayref)

Returns an arrayref containing error messages.

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

Add a new error.

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

Clean errors.

    $c->error(0);
$c->engine

Contains the engine instance. Stringifies to the class.

$c->log

Contains the logging object. 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.

$c->plugin( $name, $class, @args )

Instant plugins for Catalyst. Classdata accessor/mutator will be created, class loaded and instantiated.

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

    $c->prototype->define_javascript_functions;
$c->request
$c->req

Returns a Catalyst::Request object.

    my $req = $c->req;
$c->response
$c->res

Returns a Catalyst::Response object.

    my $res = $c->res;
$c->state

Contains the return value of the last executed action.

$c->stash

Returns a hashref containing all your data.

    print $c->stash->{foo};

Keys may be set in the stash by assigning to the hash reference, or by passing either a single hash reference or a list of key/value pairs as arguments.

For example:

    $c->stash->{foo} ||= 'yada';
    $c->stash( { moose => 'majestic', qux => 0 } );
    $c->stash( bar => 1, gorch => 2 );
$c->welcome_message

Returns the Catalyst welcome HTML page.

INTERNAL METHODS

$c->benchmark($coderef)

Takes a coderef with arguments and returns elapsed time as float.

    my ( $elapsed, $status ) = $c->benchmark( sub { return 1 } );
    $c->log->info( sprintf "Processing took %f seconds", $elapsed );
$c->components

Contains the components.

$c->counter

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

$c->depth

Returns the actual forward depth.

$c->dispatch

Dispatch request to actions.

$c->execute($class, $coderef)

Execute a coderef in given class and catch exceptions. Errors are available via $c->error.

$c->finalize

Finalize request.

$c->finalize_body

Finalize body.

$c->finalize_cookies

Finalize cookies.

$c->finalize_error

Finalize error.

$c->finalize_headers

Finalize headers.

$c->finalize_output

An alias for finalize_body.

$c->finalize_read

Finalize the input after reading is complete.

$c->finalize_uploads

Finalize uploads. Cleans up any temporary files.

$c->get_action( $action, $namespace, $inherit )

Get an action in a given namespace.

handle_request( $class, @arguments )

Handles the request.

$c->prepare(@arguments)

Turns the engine-specific request( Apache, CGI ... ) into a Catalyst context .

$c->prepare_action

Prepare action.

$c->prepare_body

Prepare message body.

$c->prepare_body_chunk( $chunk )

Prepare a chunk of data before sending it to HTTP::Body.

$c->prepare_body_parameters

Prepare body parameters.

$c->prepare_connection

Prepare connection.

$c->prepare_cookies

Prepare cookies.

$c->prepare_headers

Prepare headers.

$c->prepare_parameters

Prepare parameters.

$c->prepare_path

Prepare path and base.

$c->prepare_query_parameters

Prepare query parameters.

$c->prepare_read

Prepare the input for reading.

$c->prepare_request

Prepare the engine request.

$c->prepare_uploads

Prepare uploads.

$c->prepare_write

Prepare the output for writing.

$c->read( [$maxlength] )

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

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

$c->run

Starts the engine.

$c->set_action( $action, $code, $namespace, $attrs )

Set an action in a given namespace.

$c->setup_actions($component)

Setup actions for a component.

$c->setup_components

Setup components.

$c->setup_dispatcher
$c->setup_engine
$c->setup_home
$c->setup_log
$c->setup_plugins
$c->write( $data )

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

version

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

CASE SENSITIVITY

By default Catalyst is not case sensitive, so MyApp::C::FOO::Bar becomes /foo/bar.

But you can activate case sensitivity with a config parameter.

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

So MyApp::C::Foo::Bar becomes /Foo/Bar.

ON-DEMAND PARSER

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;

PROXY SUPPORT

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 '127.0.0.1' and the server's hostname will appear to be 'localhost' regardless of the virtual host the user connected through.

Catalyst will automatically detect this situation when you are running both 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 2 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;

THREAD SAFETY

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.

SUPPORT

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

SEE ALSO

Catalyst::Manual - The Catalyst Manual
Catalyst::Engine - Core Engine
Catalyst::Log - The Log Class.
Catalyst::Request - The Request Object
Catalyst::Response - The Response Object
Catalyst::Test - The test suite.

CREDITS

Andy Grundman

Andy Wardley

Andreas Marienborg

Andrew Bramble

Andrew Ford

Andrew Ruthven

Arthur Bergman

Autrijus Tang

Christian Hansen

Christopher Hicks

Dan Sully

Danijel Milicevic

David Naughton

Gary Ashton Jones

Geoff Richards

Jesse Sheidlower

Jesse Vincent

Jody Belka

Johan Lindstrom

Juan Camacho

Leon Brocard

Marcus Ramberg

Matt S Trout

Robert Sedlacek

Tatsuhiko Miyagawa

Ulf Edvinsson

Yuval Kogman

AUTHOR

Sebastian Riedel, sri@oook.de

LICENSE

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