arguments at the end of your URL, you must use regex action keys. See
L</URL Path Handling> below.
-=item * B<Chained>
-
-The C<Chained> attribute allows you to chain public path parts together
-by their private names. A chain part's path can be specified with C<PathPart>
-and can be declared to expect an arbitrary number of arguments. The endpoint
-of the chain specifies how many arguments it gets through the C<Args>
-attribute. C<:Args(0)> would be none at all, C<:Args> without an integer
-would be unlimited. The path parts that aren't endpoints are using
-C<CaptureArgs> to specify how many parameters they expect to receive. As an
-example setup:
-
- package MyApp::Controller::Greeting;
- use base qw/ Catalyst::Controller /;
-
- # this is the beginning of our chain
- sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
- my ( $self, $c, $integer ) = @_;
- $c->stash->{ message } = "Hello ";
- $c->stash->{ arg_sum } = $integer;
- }
-
- # this is our endpoint, because it has no :CaptureArgs
- sub world : PathPart('world') Chained('hello') Args(1) {
- my ( $self, $c, $integer ) = @_;
- $c->stash->{ message } .= "World!";
- $c->stash->{ arg_sum } += $integer;
-
- $c->response->body( join "<br/>\n" =>
- $c->stash->{ message }, $c->stash->{ arg_sum } );
- }
-
-The debug output provides a separate table for chained actions, showing
-the whole chain as it would match and the actions it contains. Here's
-an example of the startup output with our actions above:
-
- ...
- [debug] Loaded Path Part actions:
- .-----------------------+------------------------------.
- | Path Spec | Private |
- +-----------------------+------------------------------+
- | /hello/*/world/* | /greeting/hello (1) |
- | | => /greeting/world |
- '-----------------------+------------------------------'
- ...
-
-As you can see, Catalyst only deals with chains as whole path and
-builds one for each endpoint, which are the actions with C<:Chained>
-but without C<:CaptureArgs>.
-
-Let's assume this application gets a request at the path
-C</hello/23/world/12>, what happens then? First, Catalyst will dispatch
-to the C<hello> action and pass the value C<23> as argument to it after
-the context. It does so because we have previously used C<:CaptureArgs(1)>
-to declare that it has one path part after itself as it's argument. We
-told Catalyst that this is the beginning of the chain by specifying
-C<:Chained('/')>. Also note that instead of saying C<:PathPart('hello')>
-we could also just have said C<:PathPart>, as it defaults to the name of
-the action.
-
-After C<hello> has run, Catalyst goes on to dispatch to the C<world>
-action. This is the last action to be called, as Catalyst knows this
-is an endpoint because we specified no C<:CaptureArgs> attribute. Nevertheless
-we specify that this action expects an argument, but at this point we're
-using C<:Args(1)> to do that. We could also have said C<:Args> or leave
-it out alltogether, which would mean this action gets all arguments that
-are there. This action's C<:Chained> attribute says C<hello> and tells
-Catalyst that the C<hello> action in the current controller is it's
-parent.
-
-With this we have built a chain consisting of two public path parts.
-C<hello> captures one part of the path as it's argument, and also specifies
-the path root as it's parent. So this part is C</hello/$arg>. The next part
-is the endpoint C<world>, expecting one argument. It sums up to the path
-part C<world/$arg>. This leads to a complete chain of
-C</hello/$arg/world/$arg> which is matched against the requested paths.
-
-This example application would, if run and called by e.g.
-C</hello/23/world/12>, set the stash value C<message> to C<Hello > and
-the value C<arg_sum> to C<23>. The C<world> action would then append
-C<World!> to C<message> and add C<12> to the stash's C<arg_sum> value.
-For the sake of simplicity no view is shown. Instead we just put the
-values of the stash into our body. So the output would look like:
-
- Hello World!
- 35
-
-And our test server would've given us this debugging output for the
-request:
-
- ...
- [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
- [debug] Path is "/greeting/world"
- [debug] Arguments are "12"
- [info] Request took 0.164113s (6.093/s)
- .------------------------------------------+-----------.
- | Action | Time |
- +------------------------------------------+-----------+
- | /greeting/hello | 0.000029s |
- | /greeting/world | 0.000024s |
- '------------------------------------------+-----------'
- ...
-
-What would be common usecases of this dispatching technique? It gives the
-possibility to split up logic that contains steps that each depend on each
-other. An example would be, for example, a wiki path like
-C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
-these actions:
-
- sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
- my ( $self, $c, $page_name ) = @_;
- # load the page named $page_name and put the object
- # into the stash
- }
-
- sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
- my ( $self, $c, $revision_id ) = @_;
- # use the page object in the stash to get at it's
- # revision with number $revision_id
- }
-
- sub view : PathPart Chained('rev') Args(0) {
- my ( $self, $c ) = @_;
- # display the revision in our stash. An other option
- # would be to forward a compatible object to the action
- # that displays the default wiki pages, unless we want
- # a different interface here, for example restore
- # functionality.
- }
-
-It would now be possible to add other endpoints. For example C<restore> to
-restore this specific revision as current state.
-
-Also, you of course don't have to put all the chained actions in one
-controller. The specification of the parent through C<:Chained> also takes
-an absolute action path as it's argument. Just specify it with a leading
-C</>.
-
-If you want, for example, to have actions for the public paths
-C</foo/12/edit> and C</foo/12>, just specify two actions with
-C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
-path needs a C<:CaptureArgs(1)> attribute and a endpoint with
-C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
-the action just a C<:Args(1)> to mark it as endpoint. This sums up to
-this debugging output:
-
- ...
- [debug] Loaded Path Part actions:
- .-----------------------+------------------------------.
- | Path Spec | Private |
- +-----------------------+------------------------------+
- | /foo/* | /controller/foo_view |
- | /foo/*/edit | /controller/foo_load (1) |
- | | => /controller/edit |
- '-----------------------+------------------------------'
- ...
-
-Here's a more detailed specification of the attributes belonging to
-C<:Chained>:
-
-=over 8
-
-=item PathPart
-
-Sets the name of this part of the chain. If it is specified without
-arguments, it takes the name of the action as default. So basically
-C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
-This can also contain slashes to bind to a deeper level. An action
-with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
-C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
-effect as using C<:PathPart>, it would default to the action name.
-
-=item Chained
-
-Has to be specified for every child in the chain. Possible values are
-absolute and relative private action paths, with the relatives pointing
-to the current controller, or a single slash C</> to tell Catalyst that
-this is the root of a chain. The attribute C<:Chained> without aguments
-also defaults to the C</> behaviour.
-
-Due to the fact that you can specify an absolute path to the parent
-action, it doesn't matter to Catalyst where that parent is located. So,
-if your design requests it, you can redispatch a chain through every
-controller or namespace you want.
-
-Another interesting possibility gives C<:Chained('.')>, which chains
-itself to an action with the path of the current controllers namespace.
-For example:
-
- # in MyApp::Controller::Foo
- sub bar : Chained CaptureArgs(1) { ... }
-
- # in MyApp::Controller::Foo::Bar
- sub baz : Chained('.') Args(1) { ... }
-
-This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
-as argument to Chained here chains the C<baz> action to an action with
-the path of the current controller namespace, namely C</foo/bar>. That
-action chains directly to C</>, so the above chain comes out as end
-product.
-
-=item CaptureArgs
-
-Also has to be specified for every part of the chain that is not an
-endpoint. With this attribute Catalyst knows how many of the following
-parts of the path (separated by C</>) this action wants to captures as
-it's arguments. If it doesn't expect any, just specify C<:CaptureArgs(0)>.
-The captures get passed to the action's C<@_> right after the context,
-but you can also find them as array reference in
-C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
-level of the action in the chain that captured the parts of the path.
-
-An action that is part of a chain (read: that has a C<:Chained> attribute)
-but has no C<:CaptureArgs> attribute is treated by Catalyst as a chain end.
-
-=item Args
-
-By default, endpoints receive the rest of the arguments in the path. You
-can tell Catalyst through C<:Args> explicitly how many arguments your
-endpoint expects, just like you can with C<:CaptureArgs>. Note that this
-also influences if this chain is invoked on a request. A chain with an
-endpoint specifying one argument will only match if exactly one argument
-exists in the path.
-
-You can specify an exact number of arguments like C<:Args(3)>, including
-C<0>. If you just say C<:Args> without any arguments, it is the same as
-leaving it out alltogether: The chain is matched independent of the number
-of path parts after the endpoint.
-
-Just like with C<:CaptureArgs>, the arguments get passed to the action in
-C<@_> after the context object. They can also be reached through
-C<$c-E<gt>request-E<gt>arguments>.
-
-=back
-
-Note that the list of C<auto> actions called depends on the private path
-of the endpoint of the chain, not on the chained actions way. The C<auto>
-actions will be run before the chain dispatching begins. In every other
-aspect, C<auto> actions behave as documented.
-
-The C<forward>ing to other actions does just what you would expect. But if
-you C<detach> out of a chain, the rest of the chain will not get called
-after the C<detach> returned.
-
=item * B<Top-level> (B<Global>)
package MyApp::Controller::Foo;
explanation of the pre-defined meaning of Catalyst component class
names.
+=item * B<Chained>
+
+Catalyst also provides a method to build and dispatch chains of actions,
+like
+
+ sub foo : Chained : CaptureArgs(1) {
+ my ( $self, $c, $arg ) = @_;
+ ...
+ }
+
+ sub bar : Chained('foo') : Args(1) {
+ my ( $self, $c, $arg ) = @_;
+ ...
+ }
+
+to handle a C</foo/*/bar/*> path. For more information about this dispatch
+type, please read L<Catalyst::DispatchType::Chained>.
+
=item * B<Private>
sub foo : Private { }
projects / catagits/Catalyst-Runtime.git / blobdiff