Provided by: libcatalyst-perl_5.90053-1_all 
NAME
Catalyst - The Elegant MVC Web Application Framework
SYNOPSIS
See the Catalyst::Manual distribution for comprehensive documentation and tutorials.
# Install Catalyst::Devel for helpers and other development tools
# use the helper to create a new application
catalyst.pl MyApp
# add models, views, controllers
script/myapp_create.pl model MyDatabase DBIC::Schema create=static dbi:SQLite:/path/to/db
script/myapp_create.pl view MyTemplate TT
script/myapp_create.pl controller Search
# built in testserver -- use -r to restart automatically on changes
# --help to see all available options
script/myapp_server.pl
# command line testing interface
script/myapp_test.pl /yada
### in lib/MyApp.pm
use Catalyst qw/-Debug/; # include plugins here as well
### In lib/MyApp/Controller/Root.pm (autocreated)
sub foo : Chained('/') Args() { # 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} =
$c->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 : Chained('/') PathPart('/bar/of/soap') Args() { ... }
# called after all actions are finished
sub end : Action {
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
}
See Catalyst::Manual::Intro for additional information.
DESCRIPTION
Catalyst is a modern framework for making web applications without the pain usually
associated with this process. This document is a reference to the main Catalyst
application. If you are a new user, we suggest you start with Catalyst::Manual::Tutorial
or Catalyst::Manual::Intro.
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, i.e.,
"Catalyst::Plugin::My::Module" becomes "My::Module".
use Catalyst qw/My::Module/;
If your plugin starts with a name other than "Catalyst::Plugin::", you can fully qualify
the name by using a unary plus:
use Catalyst qw/
My::Module
+Fully::Qualified::Plugin::Name
/;
Special flags like "-Debug" 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
the order in which they appear.
The following flags are supported:
-Debug
Enables debug output. You can also force this setting from the system environment with
CATALYST_DEBUG or <MYAPP>_DEBUG. The environment settings override the application, with
<MYAPP>_DEBUG having the highest priority.
This sets the log level to 'debug' and enables full debug output on the error screen. If
you only want the latter, see $c->debug.
-Home
Forces Catalyst to use a specific home directory, e.g.:
use Catalyst qw[-Home=/usr/mst];
This can also be done in the shell environment by setting either the "CATALYST_HOME"
environment variable or "MYAPP_HOME"; where "MYAPP" is replaced with the uppercased name
of your application, any "::" in the name will be replaced with underscores, e.g.
MyApp::Web should use MYAPP_WEB_HOME. If both variables are set, the MYAPP_HOME one will
be used.
If none of these are set, Catalyst will attempt to automatically detect the home
directory. If you are working in a development environment, Catalyst will try and find the
directory containing either Makefile.PL, Build.PL, dist.ini, or cpanfile. If the
application has been installed into the system (i.e. you have done "make install"), then
Catalyst will use the path to your application module, without the .pm extension (e.g.,
/foo/MyApp if your application was installed at /foo/MyApp.pm)
-Log
use Catalyst '-Log=warn,fatal,error';
Specifies a comma-delimited list of log levels.
-Stats
Enables statistics collection and reporting.
use Catalyst qw/-Stats=1/;
You can also force this setting from the system environment with CATALYST_STATS or
<MYAPP>_STATS. The environment settings override the application, with <MYAPP>_STATS
having the highest priority.
Stats are also enabled if debugging is enabled.
METHODS
INFORMATION ABOUT THE CURRENT REQUEST
$c->action
Returns a Catalyst::Action object for the current action, which stringifies to the action
name. See Catalyst::Action.
$c->namespace
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';
$c->request
$c->req
Returns the current Catalyst::Request object, giving access to information about the
current client request (including parameters, cookies, HTTP headers, etc.). See
Catalyst::Request.
REQUEST FLOW HANDLING
$c->forward( $action [, \@arguments ] )
$c->forward( $class, $method, [, \@arguments ] )
This is one way of calling another action (method) in the same or a different controller.
You can also use "$self->my_method($c, @args)" in the same controller or
"$c->controller('MyController')->my_method($c, @args)" in a different controller. The
main difference is that 'forward' uses some of the Catalyst request cycle overhead,
including debugging, which may be useful to you. On the other hand, there are some
complications to using 'forward', restrictions on values returned from 'forward', and it
may not handle errors as you prefer. Whether you use 'forward' or not is up to you; it is
not considered superior to the other ways to call a method.
'forward' calls another action, by its private name. If you give a class name but no
method, "process()" is called. You may also optionally pass arguments in an arrayref. The
action will receive the arguments in @_ and "$c->req->args". Upon returning from the
function, "$c->req->args" will be restored to the previous values.
Any data "return"ed from the action forwarded to, will be returned by the call to forward.
my $foodata = $c->forward('/foo');
$c->forward('index');
$c->forward(qw/Model::DBIC::Foo do_stuff/);
$c->forward('View::TT');
Note that forward implies an "eval { }" around the call (actually execute does), thus
rendering all exceptions thrown by the called action non-fatal and pushing them onto
$c->error instead. If you want "die" to propagate you need to do something like:
$c->forward('foo');
die join "\n", @{ $c->error } if @{ $c->error };
Or make sure to always return true values from your actions and write your code like this:
$c->forward('foo') || return;
Another note is that "$c->forward" always returns a scalar because it actually returns
$c->state which operates in a scalar context. Thus, something like:
return @array;
in an action that is forwarded to is going to return a scalar, i.e. how many items are in
that array, which is probably not what you want. If you need to return an array then
return a reference to it, or stash it like so:
$c->stash->{array} = \@array;
and access it from the stash.
Keep in mind that the "end" method used is that of the caller action. So a "$c->detach"
inside a forwarded action would run the "end" method from the original action requested.
$c->detach( $action [, \@arguments ] )
$c->detach( $class, $method, [, \@arguments ] )
$c->detach()
The same as forward, but doesn't return to the previous action when processing is
finished.
When called with no arguments it escapes the processing chain entirely.
$c->visit( $action [, \@arguments ] )
$c->visit( $action [, \@captures, \@arguments ] )
$c->visit( $class, $method, [, \@arguments ] )
$c->visit( $class, $method, [, \@captures, \@arguments ] )
Almost the same as forward, but does a full dispatch, instead of just calling the new
$action / "$class->$method". This means that "begin", "auto" and the method you go to are
called, just like a new request.
In addition both "$c->action" and "$c->namespace" are localized. This means, for example,
that "$c->action" methods such as name, class and reverse return information for the
visited action when they are invoked within the visited action. This is different from
the behavior of forward, which continues to use the $c->action object from the caller
action even when invoked from the called action.
"$c->stash" is kept unchanged.
In effect, visit allows you to "wrap" another action, just as it would have been called by
dispatching from a URL, while the analogous go allows you to transfer control to another
action as if it had been reached directly from a URL.
$c->go( $action [, \@arguments ] )
$c->go( $action [, \@captures, \@arguments ] )
$c->go( $class, $method, [, \@arguments ] )
$c->go( $class, $method, [, \@captures, \@arguments ] )
The relationship between "go" and visit is the same as the relationship between forward
and detach. Like "$c->visit", "$c->go" will perform a full dispatch on the specified
action or method, with localized "$c->action" and "$c->namespace". Like "detach", "go"
escapes the processing of the current request chain on completion, and does not return to
its caller.
@arguments are arguments to the final destination of $action. @captures are arguments to
the intermediate steps, if any, on the way to the final sub of $action.
$c->response
$c->res
Returns the current Catalyst::Response object, see there for details.
$c->stash
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 (for this you must use a session; see
Catalyst::Plugin::Session for a complete system integrated with Catalyst).
$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::View::TT' );
$c->error
$c->error($error, ...)
$c->error($arrayref)
Returns an arrayref containing error messages. If Catalyst encounters an error while
processing a request, it stores the error in $c->error. This method should only be used
to store fatal error messages.
my @error = @{ $c->error };
Add a new error.
$c->error('Something bad happened');
$c->state
Contains the return value of the last executed action. Note that << $c->state >> operates
in a scalar context which means that all values it returns are scalar.
$c->clear_errors
Clear errors. You probably don't want to clear the errors unless you are implementing a
custom error screen.
This is equivalent to running
$c->error(0);
COMPONENT ACCESSORS
$c->controller($name)
Gets a Catalyst::Controller instance by name.
$c->controller('Foo')->do_stuff;
If the name is omitted, will return the controller for the dispatched action.
If you want to search for controllers, pass in a regexp as the argument.
# find all controllers that start with Foo
my @foo_controllers = $c->controller(qr{^Foo});
$c->model($name)
Gets a Catalyst::Model instance by name.
$c->model('Foo')->do_stuff;
Any extra arguments are directly passed to ACCEPT_CONTEXT.
If the name is omitted, it will look for
- a model object in $c->stash->{current_model_instance}, then
- a model name in $c->stash->{current_model}, then
- a config setting 'default_model', or
- check if there is only one model, and return it if that's the case.
If you want to search for models, pass in a regexp as the argument.
# find all models that start with Foo
my @foo_models = $c->model(qr{^Foo});
$c->view($name)
Gets a Catalyst::View instance by name.
$c->view('Foo')->do_stuff;
Any extra arguments are directly passed to ACCEPT_CONTEXT.
If the name is omitted, it will look for
- a view object in $c->stash->{current_view_instance}, then
- a view name in $c->stash->{current_view}, then
- a config setting 'default_view', or
- check if there is only one view, and return it if that's the case.
If you want to search for views, pass in a regexp as the argument.
# find all views that start with Foo
my @foo_views = $c->view(qr{^Foo});
$c->controllers
Returns the available names which can be passed to $c->controller
$c->models
Returns the available names which can be passed to $c->model
$c->views
Returns the available names which can be passed to $c->view
$c->comp($name)
$c->component($name)
Gets a component object by name. This method is not recommended, unless you want to get a
specific component by full class. "$c->controller", "$c->model", and "$c->view" should be
used instead.
If $name is a regexp, a list of components matched against the full component name will be
returned.
If Catalyst can't find a component by name, it will fallback to regex matching by default.
To disable this behaviour set disable_component_resolution_regex_fallback to a true value.
__PACKAGE__->config( disable_component_resolution_regex_fallback => 1 );
CLASS DATA AND HELPER CLASSES
$c->config
Returns or takes a hashref containing the application's configuration.
__PACKAGE__->config( { db => 'dsn:SQLite:foo.db' } );
You can also use a "YAML", "XML" or Config::General config file like "myapp.conf" in your
applications home directory. See Catalyst::Plugin::ConfigLoader.
Cascading configuration
The config method is present on all Catalyst components, and configuration will be merged
when an application is started. Configuration loaded with Catalyst::Plugin::ConfigLoader
takes precedence over other configuration, followed by configuration in your top level
"MyApp" class. These two configurations are merged, and then configuration data whose hash
key matches a component name is merged with configuration for that component.
The configuration for a component is then passed to the "new" method when a component is
constructed.
For example:
MyApp->config({ 'Model::Foo' => { bar => 'baz', overrides => 'me' } });
MyApp::Model::Foo->config({ quux => 'frob', overrides => 'this' });
will mean that "MyApp::Model::Foo" receives the following data when constructed:
MyApp::Model::Foo->new({
bar => 'baz',
quux => 'frob',
overrides => 'me',
});
It's common practice to use a Moose attribute on the receiving component to access the
config value.
package MyApp::Model::Foo;
use Moose;
# this attr will receive 'baz' at construction time
has 'bar' => (
is => 'rw',
isa => 'Str',
);
You can then get the value 'baz' by calling $c->model('Foo')->bar (or $self->bar inside
code in the model).
NOTE: you MUST NOT call "$self->config" or "__PACKAGE__->config" as a way of reading
config within your code, as this will not give you the correctly merged config back. You
MUST take the config values supplied to the constructor and use those instead.
$c->log
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, set the logger with the
"__PACKAGE__->log" method prior to calling "__PACKAGE__->setup".
__PACKAGE__->log( MyLogger->new );
__PACKAGE__->setup;
And later:
$c->log->info( 'Now logging with my own logger!' );
Your log class should implement the methods described in Catalyst::Log.
$c->debug
Returns 1 if debug mode is enabled, 0 otherwise.
You can enable debug mode in several ways:
By calling myapp_server.pl with the -d flag
With the environment variables MYAPP_DEBUG, or CATALYST_DEBUG
The -Debug option in your MyApp.pm
By declaring "sub debug { 1 }" in your MyApp.pm.
The first three also set the log level to 'debug'.
Calling "$c->debug(1)" has no effect.
$c->dispatcher
Returns the dispatcher instance. See Catalyst::Dispatcher.
$c->engine
Returns the engine instance. See Catalyst::Engine.
UTILITY METHODS
$c->path_to(@path)
Merges @path with "$c->config->{home}" and returns a Path::Class::Dir object. Note you can
usually use this object as a filename, but sometimes you will have to explicitly stringify
it yourself by calling the "->stringify" method.
For example:
$c->path_to( 'db', 'sqlite.db' );
MyApp->setup
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 "use Catalyst" line.
MyApp->setup;
MyApp->setup( qw/-Debug/ );
Note: You should not wrap this method with method modifiers or bad things will happen -
wrap the "setup_finalize" method instead.
$app->setup_finalize
A hook to attach modifiers to. This method does not do anything except set the
"setup_finished" accessor.
Applying method modifiers to the "setup" method doesn't work, because of quirky things
done for plugin setup.
Example:
after setup_finalize => sub {
my $app = shift;
## do stuff here..
};
$c->uri_for( $path?, @args?, \%query_values? )
$c->uri_for( $action, \@captures?, @args?, \%query_values? )
Constructs an absolute URI object based on the application root, the provided path, and
the additional arguments and query parameters provided. When used as a string, provides a
textual URI. If you need more flexibility than this (i.e. the option to provide relative
URIs etc.) see Catalyst::Plugin::SmartURI.
If no arguments are provided, the URI for the current action is returned. To return the
current action and also provide @args, use "$c->uri_for( $c->action, @args )".
If the first argument is a string, it is taken as a public URI path relative to
"$c->namespace" (if it doesn't begin with a forward slash) or relative to the application
root (if it does). It is then merged with "$c->request->base"; any @args are appended as
additional path components; and any %query_values are appended as "?foo=bar" parameters.
If the first argument is a Catalyst::Action it represents an action which will have its
path resolved using "$c->dispatcher->uri_for_action". The optional "\@captures" argument
(an arrayref) allows passing the captured variables that are needed to fill in the paths
of Chained and Regex actions; once the path is resolved, "uri_for" continues as though a
path was provided, appending any arguments or parameters and creating an absolute URI.
The captures for the current request can be found in "$c->request->captures", and actions
can be resolved using "Catalyst::Controller->action_for($name)". If you have a private
action path, use "$c->uri_for_action" instead.
# Equivalent to $c->req->uri
$c->uri_for($c->action, $c->req->captures,
@{ $c->req->args }, $c->req->params);
# For the Foo action in the Bar controller
$c->uri_for($c->controller('Bar')->action_for('Foo'));
# Path to a static resource
$c->uri_for('/static/images/logo.png');
$c->uri_for_action( $path, \@captures_and_args?, @args?, \%query_values? )
$c->uri_for_action( $action, \@captures_and_args?, @args?, \%query_values? )
$path
A private path to the Catalyst action you want to create a URI for.
This is a shortcut for calling "$c->dispatcher->get_action_by_path($path)" and passing
the resulting $action and the remaining arguments to "$c->uri_for".
You can also pass in a Catalyst::Action object, in which case it is passed to
"$c->uri_for".
Note that although the path looks like a URI that dispatches to the wanted action, it
is not a URI, but an internal path to that action.
For example, if the action looks like:
package MyApp::Controller::Users;
sub lst : Path('the-list') {}
You can use:
$c->uri_for_action('/users/lst')
and it will create the URI /users/the-list.
\@captures_and_args?
Optional array reference of Captures (i.e. "<CaptureArgs or $c-"req->captures>) and
arguments to the request. Usually used with Catalyst::DispatchType::Chained to
interpolate all the parameters in the URI.
@args?
Optional list of extra arguments - can be supplied in the "\@captures_and_args?" array
ref, or here - whichever is easier for your code.
Your action can have zero, a fixed or a variable number of args (e.g. Args(1) for a
fixed number or "Args()" for a variable number)..
\%query_values?
Optional array reference of query parameters to append. E.g.
{ foo => 'bar' }
will generate
/rest/of/your/uri?foo=bar
$c->welcome_message
Returns the Catalyst welcome HTML page.
run_options
Contains a hash of options passed from the application script, including the original ARGV
the script received, the processed values from that ARGV and any extra arguments to the
script which were not processed.
This can be used to add custom options to your application's scripts and setup your
application differently depending on the values of these options.
INTERNAL METHODS
These methods are not meant to be used by end users.
$c->components
Returns a hash of components.
$c->context_class
Returns or sets the context class.
$c->counter
Returns a hashref containing coderefs and execution counts (needed for deep recursion
detection).
$c->depth
Returns the number of actions on the current internal execution stack.
$c->dispatch
Dispatches a request to actions.
$c->dispatcher_class
Returns or sets the dispatcher class.
$c->dump_these
Returns a list of 2-element array references (name, structure) pairs that will be dumped
on the error page in debug mode.
$c->engine_class
Returns or sets the engine class.
$c->execute( $class, $coderef )
Execute a coderef in given class and catch exceptions. Errors are available via $c->error.
$c->finalize
Finalizes the request.
$c->finalize_body
Finalizes body.
$c->finalize_cookies
Finalizes cookies.
$c->finalize_error
Finalizes error.
$c->finalize_headers
Finalizes headers.
$c->finalize_output
An alias for finalize_body.
$c->finalize_read
Finalizes the input after reading is complete.
$c->finalize_uploads
Finalizes uploads. Cleans up any temporary files.
$c->get_action( $action, $namespace )
Gets an action in a given namespace.
$c->get_actions( $action, $namespace )
Gets all actions of a given name in a namespace and all parent namespaces.
$app->handle_request( @arguments )
Called to handle each HTTP request.
$class->prepare( @arguments )
Creates a Catalyst context from an engine-specific request (Apache, CGI, etc.).
$c->prepare_action
Prepares action. See Catalyst::Dispatcher.
$c->prepare_body
Prepares message body.
$c->prepare_body_chunk( $chunk )
Prepares a chunk of data before sending it to HTTP::Body.
See Catalyst::Engine.
$c->prepare_body_parameters
Prepares body parameters.
$c->prepare_connection
Prepares connection.
$c->prepare_cookies
Prepares cookies by ensuring that the attribute on the request object has been built.
$c->prepare_headers
Prepares request headers by ensuring that the attribute on the request object has been
built.
$c->prepare_parameters
Prepares parameters.
$c->prepare_path
Prepares path and base.
$c->prepare_query_parameters
Prepares query parameters.
$c->log_request
Writes information about the request to the debug logs. This includes:
• Request method, path, and remote IP address
• Query keywords (see "query_keywords" in Catalyst::Request)
• Request parameters
• File uploads
$c->log_response
Writes information about the response to the debug logs by calling
"$c->log_response_status_line" and "$c->log_response_headers".
$c->log_response_status_line($response)
Writes one line of information about the response to the debug logs. This includes:
• Response status code
• Content-Type header (if present)
• Content-Length header (if present)
$c->log_response_headers($headers);
Hook method which can be wrapped by plugins to log the response headers. No-op in the
default implementation.
$c->log_request_parameters( query => {}, body => {} )
Logs request parameters to debug logs
$c->log_request_uploads
Logs file uploads included in the request to the debug logs. The parameter name,
filename, file type, and file size are all included in the debug logs.
$c->log_request_headers($headers);
Hook method which can be wrapped by plugins to log the request headers. No-op in the
default implementation.
$c->log_headers($type => $headers)
Logs HTTP::Headers (either request or response) to the debug logs.
$c->prepare_read
Prepares the input for reading.
$c->prepare_request
Prepares the engine request.
$c->prepare_uploads
Prepares uploads.
$c->prepare_write
Prepares the output for writing.
$c->request_class
Returns or sets the request class. Defaults to Catalyst::Request.
$c->response_class
Returns or sets the response class. Defaults to Catalyst::Response.
$c->read( [$maxlength] )
Reads 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 => 1)" to use this directly.
Warning: If you use read(), Catalyst will not process the body, so you will not be able to
access POST parameters or file uploads via $c->request. You must handle all body parsing
yourself.
$c->run
Starts the engine.
$c->set_action( $action, $code, $namespace, $attrs )
Sets an action in a given namespace.
$c->setup_actions($component)
Sets up actions for a component.
$c->setup_components
This method is called internally to set up the application's components.
It finds modules by calling the locate_components method, expands them to package names
with the expand_component_module method, and then installs each component into the
application.
The "setup_components" config option is passed to both of the above methods.
Installation of each component is performed by the setup_component method, below.
$c->locate_components( $setup_component_config )
This method is meant to provide a list of component modules that should be setup for the
application. By default, it will use Module::Pluggable.
Specify a "setup_components" config option to pass additional options directly to
Module::Pluggable. To add additional search paths, specify a key named "search_extra" as
an array reference. Items in the array beginning with "::" will have the application class
name prepended to them.
$c->expand_component_module( $component, $setup_component_config )
Components found by "locate_components" will be passed to this method, which is expected
to return a list of component (package) names to be set up.
$c->setup_component
$c->setup_dispatcher
Sets up dispatcher.
$c->setup_engine
Sets up engine.
$c->apply_default_middlewares
Adds the following Plack middlewares to your application, since they are useful and
commonly needed:
Plack::Middleware::ReverseProxy, (conditionally added based on the status of your
$ENV{REMOTE_ADDR}, and can be forced on with "using_frontend_proxy" or forced off with
"ignore_frontend_proxy"), Plack::Middleware::LighttpdScriptNameFix (if you are using
Lighttpd), Plack::Middleware::IIS6ScriptNameFix (always applied since this middleware is
smart enough to conditionally apply itself).
Additionally if we detect we are using Nginx, we add a bit of custom middleware to solve
some problems with the way that server handles $ENV{PATH_INFO} and $ENV{SCRIPT_NAME}
$c->psgi_app
Returns a PSGI application code reference for the catalyst application $c. This is the
bare application without any middlewares applied. "${myapp}.psgi" is not taken into
account.
This is what you want to be using to retrieve the PSGI application code reference of your
Catalyst application for use in .psgi files.
$c->setup_home
Sets up the home directory.
$c->setup_log
Sets up log by instantiating a Catalyst::Log object and passing it to "log()". Pass in a
comma-delimited list of levels to set the log to.
This method also installs a "debug" method that returns a true value into the catalyst
subclass if the "debug" level is passed in the comma-delimited list, or if the
$CATALYST_DEBUG environment variable is set to a true value.
Note that if the log has already been setup, by either a previous call to "setup_log" or
by a call such as "__PACKAGE__->log( MyLogger->new )", that this method won't actually set
up the log object.
$c->setup_plugins
Sets up plugins.
$c->setup_stats
Sets up timing statistics class.
$c->registered_plugins
Returns a sorted list of the plugins which have either been stated in the import list.
If passed a given plugin name, it will report a boolean value indicating whether or not
that plugin is loaded. A fully qualified name is required if the plugin name does not
begin with "Catalyst::Plugin::".
if ($c->registered_plugins('Some::Plugin')) {
...
}
registered_middlewares
Read only accessor that returns an array of all the middleware in the order that they were
added (which is the REVERSE of the order they will be applied).
The values returned will be either instances of Plack::Middleware or of a compatible
interface, or a coderef, which is assumed to be inlined middleware
setup_middleware (?@middleware)
Read configuration information stored in configuration key "psgi_middleware" or from
passed @args.
See under "CONFIGURATION" information regarding "psgi_middleware" and how to use it to
enable Plack::Middleware
This method is automatically called during 'setup' of your application, so you really
don't need to invoke it. However you may do so if you find the idea of loading middleware
via configuration weird :). For example:
package MyApp;
use Catalyst;
__PACKAGE__->setup_middleware('Head');
__PACKAGE__->setup;
When we read middleware definitions from configuration, we reverse the list which sounds
odd but is likely how you expect it to work if you have prior experience with
Plack::Builder or if you previously used the plugin Catalyst::Plugin::EnableMiddleware
(which is now considered deprecated)
registered_data_handlers
A read only copy of registered Data Handlers returned as a Hash, where each key is a
content type and each value is a subref that attempts to decode that content type.
setup_data_handlers (?@data_handler)
Read configuration information stored in configuration key "data_handlers" or from passed
@args.
See under "CONFIGURATION" information regarding "data_handlers".
This method is automatically called during 'setup' of your application, so you really
don't need to invoke it.
default_data_handlers
Default Data Handlers that come bundled with Catalyst. Currently there are only two
default data handlers, for 'application/json' and an alternative to
'application/x-www-form-urlencoded' which supposed nested form parameters via CGI::Struct
or via CGI::Struct::XS IF you've installed it.
The 'application/json' data handler is used to parse incoming JSON into a Perl data
structure. It used either JSON::MaybeXS or JSON, depending on which is installed. This
allows you to fail back to <JSON:PP>, which is a Pure Perl JSON decoder, and has the
smallest dependency impact.
Because we don't wish to add more dependencies to Catalyst, if you wish to use this new
feature we recommend installing JSON or JSON::MaybeXS in order to get the best
performance. You should add either to your dependency list (Makefile.PL, dist.ini,
cpanfile, etc.)
$c->stack
Returns an arrayref of the internal execution stack (actions that are currently
executing).
$c->stats
Returns the current timing statistics object. By default Catalyst uses Catalyst::Stats,
but can be set otherwise with stats_class.
Even if -Stats is not enabled, the stats object is still available. By enabling it with "
$c-"stats->enabled(1) >, it can be used to profile explicitly, although MyApp.pm still
won't profile nor output anything by itself.
$c->stats_class
Returns or sets the stats (timing statistics) class. Catalyst::Stats is used by default.
$c->use_stats
Returns 1 when stats collection is enabled.
Note that this is a static method, not an accessor and should be overridden by declaring
"sub use_stats { 1 }" in your MyApp.pm, not by calling "$c->use_stats(1)".
$c->write( $data )
Writes $data to the output stream. When using this method directly, you will need to
manually set the "Content-Length" header to the length of your output data, if known.
version
Returns the Catalyst version number. Mostly useful for "powered by" messages in template
systems.
CONFIGURATION
There are a number of 'base' config variables which can be set:
• "default_model" - The default model picked if you say "$c->model". See
"$c->model($name)".
• "default_view" - The default view to be rendered or returned when "$c->view" is
called. See "$c->view($name)".
• "disable_component_resolution_regex_fallback" - Turns off the deprecated component
resolution functionality so that if any of the component methods (e.g.
"$c->controller('Foo')") are called then regex search will not be attempted on string
values and instead "undef" will be returned.
• "home" - The application home directory. In an uninstalled application, this is the
top level application directory. In an installed application, this will be the
directory containing "MyApp.pm".
• "ignore_frontend_proxy" - See "PROXY SUPPORT"
• "name" - The name of the application in debug messages and the debug and welcome
screens
• "parse_on_demand" - The request body (for example file uploads) will not be parsed
until it is accessed. This allows you to (for example) check authentication (and
reject the upload) before actually receiving all the data. See "ON-DEMAND PARSER"
• "root" - The root directory for templates. Usually this is just a subdirectory of the
home directory, but you can set it to change the templates to a different directory.
• "search_extra" - Array reference passed to Module::Pluggable to for additional
namespaces from which components will be loaded (and constructed and stored in
"$c->components").
• "show_internal_actions" - If true, causes internal actions such as "_DISPATCH" to be
shown in hit debug tables in the test server.
• "use_request_uri_for_path" - Controls if the "REQUEST_URI" or "PATH_INFO" environment
variable should be used for determining the request path.
Most web server environments pass the requested path to the application using
environment variables, from which Catalyst has to reconstruct the request base (i.e.
the top level path to / in the application, exposed as "$c->request->base") and the
request path below that base.
There are two methods of doing this, both of which have advantages and disadvantages.
Which method is used is determined by the "$c->config(use_request_uri_for_path)"
setting (which can either be true or false).
use_request_uri_for_path => 0
This is the default (and the) traditional method that Catalyst has used for
determining the path information. The path is generated from a combination of the
"PATH_INFO" and "SCRIPT_NAME" environment variables. The allows the application
to behave correctly when "mod_rewrite" is being used to redirect requests into the
application, as these variables are adjusted by mod_rewrite to take account for
the redirect.
However this method has the major disadvantage that it is impossible to correctly
decode some elements of the path, as RFC 3875 says: ""Unlike a URI path, the
PATH_INFO is not URL-encoded, and cannot contain path-segment parameters."" This
means PATH_INFO is always decoded, and therefore Catalyst can't distinguish / vs
%2F in paths (in addition to other encoded values).
use_request_uri_for_path => 1
This method uses the "REQUEST_URI" and "SCRIPT_NAME" environment variables. As
"REQUEST_URI" is never decoded, this means that applications using this mode can
correctly handle URIs including the %2F character (i.e. with "AllowEncodedSlashes"
set to "On" in Apache).
Given that this method of path resolution is provably more correct, it is
recommended that you use this unless you have a specific need to deploy your
application in a non-standard environment, and you are aware of the implications
of not being able to handle encoded URI paths correctly.
However it also means that in a number of cases when the app isn't installed
directly at a path, but instead is having paths rewritten into it (e.g. as a
.cgi/fcgi in a public_html directory, with mod_rewrite in a .htaccess file, or
when SSI is used to rewrite pages into the app, or when sub-paths of the app are
exposed at other URIs than that which the app is 'normally' based at with
"mod_rewrite"), the resolution of "$c->request->base" will be incorrect.
• "using_frontend_proxy" - See "PROXY SUPPORT".
• "encoding" - See "ENCODING"
• "abort_chain_on_error_fix"
When there is an error in an action chain, the default behavior is to continue
processing the remaining actions and then catch the error upon chain end. This can
lead to running actions when the application is in an unexpected state. If you have
this issue, setting this config value to true will promptly exit a chain when there is
an error raised in any action (thus terminating the chain early.)
use like:
__PACKAGE__->config(abort_chain_on_error_fix => 1);
In the future this might become the default behavior.
• "use_hash_multivalue_in_request"
In Catalyst::Request the methods "query_parameters", "body_parametes" and "parameters"
return a hashref where values might be scalar or an arrayref depending on the incoming
data. In many cases this can be undesirable as it leads one to writing defensive code
like the following:
my ($val) = ref($c->req->parameters->{a}) ?
@{$c->req->parameters->{a}} :
$c->req->parameters->{a};
Setting this configuration item to true will make Catalyst populate the attributes
underlying these methods with an instance of Hash::MultiValue which is used by
Plack::Request and others to solve this very issue. You may prefer this behavior to
the default, if so enable this option (be warned if you enable it in a legacy
application we are not sure if it is completely backwardly compatible).
• "psgi_middleware" - See "PSGI MIDDLEWARE".
• "data_handlers" - See "DATA HANDLERS".
INTERNAL ACTIONS
Catalyst uses internal actions like "_DISPATCH", "_BEGIN", "_AUTO", "_ACTION", and "_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);
ON-DEMAND PARSER
The request body is usually parsed at the beginning of a request, but if you want to
handle input yourself, 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 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 $c->req->uri is set to the real
host, as read from the HTTP X-Forwarded-Host header.
Additionally, you may be running your backend application on an insecure connection (port
80) while your frontend proxy is running under SSL. If there is a discrepancy in the
ports, use the HTTP header "X-Forwarded-Port" to tell Catalyst what port the frontend
listens on. This will allow all URIs to be created properly.
In the case of passing in:
X-Forwarded-Port: 443
All calls to "uri_for" will result in an https link, as is expected.
Obviously, your web server must support these headers for this to work.
In a more complex server farm environment where you may have your frontend proxy server(s)
on different machines, you will need to set a configuration option to tell Catalyst to
read the proxied data from the headers.
MyApp->config(using_frontend_proxy => 1);
If you do not wish to use the proxy support at all, you may set:
MyApp->config(ignore_frontend_proxy => 0);
Note about psgi files
Note that if you supply your own .psgi file, calling "MyApp->psgi_app(@_);", then this
will not happen automatically.
You either need to apply Plack::Middleware::ReverseProxy yourself in your psgi, for
example:
builder {
enable "Plack::Middleware::ReverseProxy";
MyApp->psgi_app
};
This will unconditionally add the ReverseProxy support, or you need to call "$app =
MyApp->apply_default_middlewares($app)" (to conditionally apply the support depending upon
your config).
See Catalyst::PSGI for more information.
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.
DATA HANDLERS
The Catalyst::Request object uses HTTP::Body to populate 'classic' HTML form parameters
and URL search query fields. However it has become common for various alternative content
types to be PUT or POSTed to your controllers and actions. People working on RESTful
APIs, or using AJAX often use JSON, XML and other content types when communicating with an
application server. In order to better support this use case, Catalyst defines a global
configuration option, "data_handlers", which lets you associate a content type with a
coderef that parses that content type into something Perl can readily access.
package MyApp::Web;
use Catalyst;
use JSON::Maybe;
__PACKAGE__->config(
data_handlers => {
'application/json' => sub { local $/; decode_json $_->getline },
},
## Any other configuration.
);
__PACKAGE__->setup;
By default Catalyst comes with a generic JSON data handler similar to the example given
above, which uses JSON::Maybe to provide either JSON::PP (a pure Perl, dependency free
JSON parser) or Cpanel::JSON::XS if you have it installed (if you want the faster XS
parser, add it to you project Makefile.PL or dist.ini, cpanfile, etc.)
The "data_handlers" configuation is a hashref whose keys are HTTP Content-Types (matched
against the incoming request type using a regexp such as to be case insensitive) and whose
values are coderefs that receive a localized version of $_ which is a filehandle object
pointing to received body.
This feature is considered an early access release and we reserve the right to alter the
interface in order to provide a performant and secure solution to alternative request body
content. Your reports welcomed!
PSGI MIDDLEWARE
You can define middleware, defined as Plack::Middleware or a compatible interface in
configuration. Your middleware definitions are in the form of an arrayref under the
configuration key "psgi_middleware". Here's an example with details to follow:
package MyApp::Web;
use Catalyst;
use Plack::Middleware::StackTrace;
my $stacktrace_middleware = Plack::Middleware::StackTrace->new;
__PACKAGE__->config(
'psgi_middleware', [
'Debug',
'+MyApp::Custom',
$stacktrace_middleware,
'Session' => {store => 'File'},
sub {
my $app = shift;
return sub {
my $env = shift;
$env->{myapp.customkey} = 'helloworld';
$app->($env);
},
},
],
);
__PACKAGE__->setup;
So the general form is:
__PACKAGE__->config(psgi_middleware => \@middleware_definitions);
Where @middleware is one or more of the following, applied in the REVERSE of the order
listed (to make it function similarly to Plack::Builder:
Middleware Object
An already initialized object that conforms to the Plack::Middleware specification:
my $stacktrace_middleware = Plack::Middleware::StackTrace->new;
__PACKAGE__->config(
'psgi_middleware', [
$stacktrace_middleware,
]);
coderef
A coderef that is an inlined middleware:
__PACKAGE__->config(
'psgi_middleware', [
sub {
my $app = shift;
return sub {
my $env = shift;
if($env->{PATH_INFO} =~m/forced/) {
Plack::App::File
->new(file=>TestApp->path_to(qw/share static forced.txt/))
->call($env);
} else {
return $app->($env);
}
},
},
]);
a scalar
We assume the scalar refers to a namespace after normalizing it using the following
rules:
(1) If the scalar is prefixed with a "+" (as in "+MyApp::Foo") then the full string is
assumed to be 'as is', and we just install and use the middleware.
(2) If the scalar begins with "Plack::Middleware" or your application namespace (the
package name of your Catalyst application subclass), we also assume then that it is a
full namespace, and use it.
(3) Lastly, we then assume that the scalar is a partial namespace, and attempt to
resolve it first by looking for it under your application namespace (for example if
you application is "MyApp::Web" and the scalar is "MyMiddleware", we'd look under
"MyApp::Web::Middleware::MyMiddleware") and if we don't find it there, we will then
look under the regular Plack::Middleware namespace (i.e. for the previous we'd try
"Plack::Middleware::MyMiddleware"). We look under your application namespace first to
let you 'override' common Plack::Middleware locally, should you find that a good idea.
Examples:
package MyApp::Web;
__PACKAGE__->config(
'psgi_middleware', [
'Debug', ## MyAppWeb::Middleware::Debug->wrap or Plack::Middleware::Debug->wrap
'Plack::Middleware::Stacktrace', ## Plack::Middleware::Stacktrace->wrap
'+MyApp::Custom', ## MyApp::Custom->wrap
],
);
a scalar followed by a hashref
Just like the previous, except the following "HashRef" is used as arguments to
initialize the middleware object.
__PACKAGE__->config(
'psgi_middleware', [
'Session' => {store => 'File'},
]);
Please see PSGI for more on middleware.
ENCODING
On request, decodes all params from encoding into a sequence of logical characters. On
response, encodes body into encoding.
Methods
encoding
Returns an instance of an "Encode" encoding
print $c->encoding->name
handle_unicode_encoding_exception ($exception_context)
Method called when decoding process for a request fails.
An $exception_context hashref is provided to allow you to override the behaviour of
your application when given data with incorrect encodings.
The default method throws exceptions in the case of invalid request parameters
(resulting in a 500 error), but ignores errors in upload filenames.
The keys passed in the $exception_context hash are:
param_value
The value which was not able to be decoded.
error_msg
The exception received from Encode.
encoding_step
What type of data was being decoded. Valid values are (currently) "params" - for
request parameters / arguments / captures and "uploads" - for request upload
filenames.
SUPPORT
IRC:
Join #catalyst on irc.perl.org.
Mailing Lists:
http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/catalyst
http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/catalyst-dev
Web:
http://catalyst.perl.org
Wiki:
http://dev.catalyst.perl.org
SEE ALSO
Task::Catalyst - All you need to start with Catalyst Catalyst::Manual - The Catalyst Manual Catalyst::Component, Catalyst::Controller - Base classes for components Catalyst::Engine - Core engine Catalyst::Log - Log class. Catalyst::Request - Request object Catalyst::Response - Response object Catalyst::Test - The test suite.
PROJECT FOUNDER
sri: Sebastian Riedel <sri@cpan.org>
CONTRIBUTORS
abw: Andy Wardley
acme: Leon Brocard <leon@astray.com>
abraxxa: Alexander Hartmaier <abraxxa@cpan.org>
Andrew Bramble
Andrew Ford <A.Ford@ford-mason.co.uk>
Andrew Ruthven
andyg: Andy Grundman <andy@hybridized.org>
audreyt: Audrey Tang
bricas: Brian Cassidy <bricas@cpan.org>
Caelum: Rafael Kitover <rkitover@io.com>
chansen: Christian Hansen
chicks: Christopher Hicks
Chisel Wright "pause@herlpacker.co.uk"
Danijel Milicevic "me@danijel.de"
David Kamholz <dkamholz@cpan.org>
David Naughton, "naughton@umn.edu"
David E. Wheeler
dhoss: Devin Austin <dhoss@cpan.org>
dkubb: Dan Kubb <dan.kubb-cpan@onautopilot.com>
Drew Taylor
dwc: Daniel Westermann-Clark <danieltwc@cpan.org>
esskar: Sascha Kiefer
fireartist: Carl Franks <cfranks@cpan.org>
frew: Arthur Axel "fREW" Schmidt <frioux@gmail.com>
gabb: Danijel Milicevic
Gary Ashton Jones
Gavin Henry "ghenry@perl.me.uk"
Geoff Richards
groditi: Guillermo Roditi <groditi@gmail.com>
hobbs: Andrew Rodland <andrew@cleverdomain.org>
ilmari: Dagfinn Ilmari Mannsaaker <ilmari@ilmari.org>
jcamacho: Juan Camacho
jester: Jesse Sheidlower "jester@panix.com"
jhannah: Jay Hannah <jay@jays.net>
Jody Belka
Johan Lindstrom
jon: Jon Schutz <jjschutz@cpan.org>
Jonathan Rockway "<jrockway@cpan.org>"
Kieren Diment "kd@totaldatasolution.com"
konobi: Scott McWhirter <konobi@cpan.org>
marcus: Marcus Ramberg <mramberg@cpan.org>
miyagawa: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
mgrimes: Mark Grimes <mgrimes@cpan.org>
mst: Matt S. Trout <mst@shadowcatsystems.co.uk>
mugwump: Sam Vilain
naughton: David Naughton
ningu: David Kamholz <dkamholz@cpan.org>
nothingmuch: Yuval Kogman <nothingmuch@woobling.org>
numa: Dan Sully <daniel@cpan.org>
obra: Jesse Vincent
Octavian Rasnita
omega: Andreas Marienborg
Oleg Kostyuk <cub.uanic@gmail.com>
phaylon: Robert Sedlacek <phaylon@dunkelheit.at>
rafl: Florian Ragwitz <rafl@debian.org>
random: Roland Lammel <lammel@cpan.org>
Robert Sedlacek "<rs@474.at>"
SpiceMan: Marcel Montes
sky: Arthur Bergman
szbalint: Balint Szilakszi <szbalint@cpan.org>
t0m: Tomas Doran <bobtfish@bobtfish.net>
Ulf Edvinsson
Viljo Marrandi "vilts@yahoo.com"
Will Hawes "info@whawes.co.uk"
willert: Sebastian Willert <willert@cpan.org>
wreis: Wallace Reis <wreis@cpan.org>
Yuval Kogman, "nothingmuch@woobling.org"
rainboxx: Matthias Dietrich, "perl@rainboxx.de"
dd070: Dhaval Dhanani <dhaval070@gmail.com>
COPYRIGHT
Copyright (c) 2005, the above named PROJECT FOUNDER and CONTRIBUTORS.
LICENSE
This library is free software. You can redistribute it and/or modify it under the same
terms as Perl itself.