1 package Catalyst::DispatchType::Chained;
4 extends 'Catalyst::DispatchType';
7 use Catalyst::ActionChain;
33 # please don't perltidy this. hairy code within.
37 Catalyst::DispatchType::Chained - Path Part DispatchType
41 # root action - captures one argument after it
42 sub foo_setup : Chained('/') PathPart('foo') CaptureArgs(1) {
43 my ( $self, $c, $foo_arg ) = @_;
47 # child action endpoint - takes one argument
48 sub bar : Chained('foo_setup') Args(1) {
49 my ( $self, $c, $bar_arg ) = @_;
59 =head2 $self->list($c)
61 Debug output for Path Part dispatch points
66 my ( $self, $c ) = @_;
68 return unless $self->_endpoints;
70 my $paths = Text::SimpleTable->new(
71 [ 35, 'Path Spec' ], [ 36, 'Private' ]
74 ENDPOINT: foreach my $endpoint (
75 sort { $a->reverse cmp $b->reverse }
76 @{ $self->_endpoints }
78 my $args = $endpoint->attributes->{Args}->[0];
79 my @parts = (defined($args) ? (("*") x $args) : '...');
84 if (my $cap = $curr->attributes->{CaptureArgs}) {
85 unshift(@parts, (("*") x $cap->[0]));
87 if (my $pp = $curr->attributes->{PartPath}) {
88 unshift(@parts, $pp->[0])
89 if (defined $pp->[0] && length $pp->[0]);
91 $parent = $curr->attributes->{Chained}->[0];
92 $curr = $self->_actions->{$parent};
93 unshift(@parents, $curr) if $curr;
95 next ENDPOINT unless $parent eq '/'; # skip dangling action
97 foreach my $p (@parents) {
99 if (my $cap = $p->attributes->{CaptureArgs}) {
100 $name .= ' ('.$cap->[0].')';
102 unless ($p eq $parents[0]) {
103 $name = "-> ${name}";
105 push(@rows, [ '', $name ]);
107 push(@rows, [ '', (@rows ? "=> " : '')."/${endpoint}" ]);
108 $rows[0][0] = join('/', '', @parts);
109 $paths->row(@$_) for @rows;
112 $c->log->debug( "Loaded Chained actions:\n" . $paths->draw . "\n" );
115 =head2 $self->match( $c, $path )
117 Calls C<recurse_match> to see if a chain matches the C<$path>.
122 my ( $self, $c, $path ) = @_;
124 my $request = $c->request;
125 return 0 if @{$request->args};
127 my @parts = split('/', $path);
129 my ($chain, $captures, $parts) = $self->recurse_match($c, '/', \@parts);
130 push @{$request->args}, @$parts if $parts && @$parts;
132 return 0 unless $chain;
134 my $action = Catalyst::ActionChain->from_chain($chain);
136 $request->action("/${action}");
137 $request->match("/${action}");
138 $request->captures($captures);
140 $c->namespace( $action->namespace );
145 =head2 $self->recurse_match( $c, $parent, \@path_parts )
147 Recursive search for a matching chain.
152 my ( $self, $c, $parent, $path_parts ) = @_;
153 my $children = $self->_children_of->{$parent};
154 return () unless $children;
157 TRY: foreach my $try_part (sort { length($b) <=> length($a) }
159 # $b then $a to try longest part first
160 my @parts = @$path_parts;
161 if (length $try_part) { # test and strip PathPart
163 ($try_part eq join('/', # assemble equal number of parts
164 splice( # and strip them off @parts as well
165 @parts, 0, scalar(@{[split('/', $try_part)]})
166 ))); # @{[]} to avoid split to @_
168 my @try_actions = @{$children->{$try_part}};
169 TRY_ACTION: foreach my $action (@try_actions) {
170 if (my $capture_attr = $action->attributes->{CaptureArgs}) {
172 # Short-circuit if not enough remaining parts
173 next TRY_ACTION unless @parts >= $capture_attr->[0];
176 my @parts = @parts; # localise
178 # strip CaptureArgs into list
179 push(@captures, splice(@parts, 0, $capture_attr->[0]));
181 # try the remaining parts against children of this action
182 my ($actions, $captures, $action_parts) = $self->recurse_match(
183 $c, '/'.$action->reverse, \@parts
185 # No best action currently
186 # OR The action has less parts
187 # OR The action has equal parts but less captured data (ergo more defined)
190 $#$action_parts < $#{$best_action->{parts}} ||
191 ($#$action_parts == $#{$best_action->{parts}} &&
192 $#$captures < $#{$best_action->{captures}}))){
194 actions => [ $action, @$actions ],
195 captures=> [ @captures, @$captures ],
196 parts => $action_parts
202 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
203 next TRY_ACTION unless $action->match($c);
205 my $args_attr = $action->attributes->{Args}->[0];
207 # No best action currently
208 # OR This one matches with fewer parts left than the current best action,
209 # And therefore is a better match
210 # OR No parts and this expects 0
211 # The current best action might also be Args(0),
212 # but we couldn't chose between then anyway so we'll take the last seen
215 @parts < @{$best_action->{parts}} ||
216 (!@parts && $args_attr eq 0)){
218 actions => [ $action ],
226 return @$best_action{qw/actions captures parts/} if $best_action;
230 =head2 $self->register( $c, $action )
232 Calls register_path for every Path attribute for the given $action.
237 my ( $self, $c, $action ) = @_;
239 my @chained_attr = @{ $action->attributes->{Chained} || [] };
241 return 0 unless @chained_attr;
243 if (@chained_attr > 1) {
244 Catalyst::Exception->throw(
245 "Multiple Chained attributes not supported registering ${action}"
249 my $children = ($self->_children_of->{ $chained_attr[0] } ||= {});
251 my @path_part = @{ $action->attributes->{PathPart} || [] };
253 my $part = $action->name;
255 if (@path_part == 1 && defined $path_part[0]) {
256 $part = $path_part[0];
257 } elsif (@path_part > 1) {
258 Catalyst::Exception->throw(
259 "Multiple PathPart attributes not supported registering " . $action->reverse()
263 if ($part =~ m(^/)) {
264 Catalyst::Exception->throw(
265 "Absolute parameters to PathPart not allowed registering " . $action->reverse()
269 $action->attributes->{PartPath} = [ $part ];
271 unshift(@{ $children->{$part} ||= [] }, $action);
273 $self->_actions->{'/'.$action->reverse} = $action;
275 unless ($action->attributes->{CaptureArgs}) {
276 unshift(@{ $self->_endpoints }, $action);
282 =head2 $self->uri_for_action($action, $captures)
284 Get the URI part for the action, using C<$captures> to fill
290 my ( $self, $action, $captures ) = @_;
292 return undef unless ($action->attributes->{Chained}
293 && !$action->attributes->{CaptureArgs});
296 my @captures = @$captures;
297 my $parent = "DUMMY";
300 if (my $cap = $curr->attributes->{CaptureArgs}) {
301 return undef unless @captures >= $cap->[0]; # not enough captures
303 unshift(@parts, splice(@captures, -$cap->[0]));
306 if (my $pp = $curr->attributes->{PartPath}) {
307 unshift(@parts, $pp->[0])
308 if (defined($pp->[0]) && length($pp->[0]));
310 $parent = $curr->attributes->{Chained}->[0];
311 $curr = $self->_actions->{$parent};
314 return undef unless $parent eq '/'; # fail for dangling action
316 return undef if @captures; # fail for too many captures
318 return join('/', '', @parts);
323 my ($self, $action) = @_;
325 return unless $action->attributes && $action->attributes->{Chained};
332 my $parent = $curr->attributes->{Chained}->[0];
333 $curr = $self->_actions->{$parent};
336 return Catalyst::ActionChain->from_chain([reverse @chain]);
339 __PACKAGE__->meta->make_immutable;
345 The C<Chained> attribute allows you to chain public path parts together
346 by their private names. A chain part's path can be specified with
347 C<PathPart> and can be declared to expect an arbitrary number of
348 arguments. The endpoint of the chain specifies how many arguments it
349 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
350 C<:Args> without an integer would be unlimited. The path parts that
351 aren't endpoints are using C<CaptureArgs> to specify how many parameters
352 they expect to receive. As an example setup:
354 package MyApp::Controller::Greeting;
355 use base qw/ Catalyst::Controller /;
357 # this is the beginning of our chain
358 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
359 my ( $self, $c, $integer ) = @_;
360 $c->stash->{ message } = "Hello ";
361 $c->stash->{ arg_sum } = $integer;
364 # this is our endpoint, because it has no :CaptureArgs
365 sub world : PathPart('world') Chained('hello') Args(1) {
366 my ( $self, $c, $integer ) = @_;
367 $c->stash->{ message } .= "World!";
368 $c->stash->{ arg_sum } += $integer;
370 $c->response->body( join "<br/>\n" =>
371 $c->stash->{ message }, $c->stash->{ arg_sum } );
374 The debug output provides a separate table for chained actions, showing
375 the whole chain as it would match and the actions it contains. Here's an
376 example of the startup output with our actions above:
379 [debug] Loaded Path Part actions:
380 .-----------------------+------------------------------.
381 | Path Spec | Private |
382 +-----------------------+------------------------------+
383 | /hello/*/world/* | /greeting/hello (1) |
384 | | => /greeting/world |
385 '-----------------------+------------------------------'
388 As you can see, Catalyst only deals with chains as whole paths and
389 builds one for each endpoint, which are the actions with C<:Chained> but
390 without C<:CaptureArgs>.
392 Let's assume this application gets a request at the path
393 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
394 to the C<hello> action and pass the value C<23> as an argument to it
395 after the context. It does so because we have previously used
396 C<:CaptureArgs(1)> to declare that it has one path part after itself as
397 its argument. We told Catalyst that this is the beginning of the chain
398 by specifying C<:Chained('/')>. Also note that instead of saying
399 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
400 defaults to the name of the action.
402 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
403 action. This is the last action to be called: Catalyst knows this is an
404 endpoint because we did not specify a C<:CaptureArgs>
405 attribute. Nevertheless we specify that this action expects an argument,
406 but at this point we're using C<:Args(1)> to do that. We could also have
407 said C<:Args> or left it out altogether, which would mean this action
408 would get all arguments that are there. This action's C<:Chained>
409 attribute says C<hello> and tells Catalyst that the C<hello> action in
410 the current controller is its parent.
412 With this we have built a chain consisting of two public path parts.
413 C<hello> captures one part of the path as its argument, and also
414 specifies the path root as its parent. So this part is
415 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
416 argument. It sums up to the path part C<world/$arg>. This leads to a
417 complete chain of C</hello/$arg/world/$arg> which is matched against the
420 This example application would, if run and called by e.g.
421 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
422 value C<arg_sum> to "23". The C<world> action would then append "World!"
423 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
424 sake of simplicity no view is shown. Instead we just put the values of
425 the stash into our body. So the output would look like:
430 And our test server would have given us this debugging output for the
434 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
435 [debug] Path is "/greeting/world"
436 [debug] Arguments are "12"
437 [info] Request took 0.164113s (6.093/s)
438 .------------------------------------------+-----------.
440 +------------------------------------------+-----------+
441 | /greeting/hello | 0.000029s |
442 | /greeting/world | 0.000024s |
443 '------------------------------------------+-----------'
446 What would be common uses of this dispatch technique? It gives the
447 possibility to split up logic that contains steps that each depend on
448 each other. An example would be, for example, a wiki path like
449 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
452 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
453 my ( $self, $c, $page_name ) = @_;
454 # load the page named $page_name and put the object
458 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
459 my ( $self, $c, $revision_id ) = @_;
460 # use the page object in the stash to get at its
461 # revision with number $revision_id
464 sub view : PathPart Chained('rev') Args(0) {
465 my ( $self, $c ) = @_;
466 # display the revision in our stash. Another option
467 # would be to forward a compatible object to the action
468 # that displays the default wiki pages, unless we want
469 # a different interface here, for example restore
473 It would now be possible to add other endpoints, for example C<restore>
474 to restore this specific revision as the current state.
476 You don't have to put all the chained actions in one controller. The
477 specification of the parent through C<:Chained> also takes an absolute
478 action path as its argument. Just specify it with a leading C</>.
480 If you want, for example, to have actions for the public paths
481 C</foo/12/edit> and C</foo/12>, just specify two actions with
482 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
483 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
484 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
485 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
486 this debugging output:
489 [debug] Loaded Path Part actions:
490 .-----------------------+------------------------------.
491 | Path Spec | Private |
492 +-----------------------+------------------------------+
493 | /foo/* | /controller/foo_view |
494 | /foo/*/edit | /controller/foo_load (1) |
495 | | => /controller/edit |
496 '-----------------------+------------------------------'
499 Here's a more detailed specification of the attributes belonging to
508 Sets the name of this part of the chain. If it is specified without
509 arguments, it takes the name of the action as default. So basically
510 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
511 This can also contain slashes to bind to a deeper level. An action
512 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
513 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
514 effect as using C<:PathPart>, it would default to the action name.
518 Sets PathPart to the path_prefix of the current controller.
522 Has to be specified for every child in the chain. Possible values are
523 absolute and relative private action paths or a single slash C</> to
524 tell Catalyst that this is the root of a chain. The attribute
525 C<:Chained> without arguments also defaults to the C</> behavior.
526 Relative action paths may use C<../> to refer to actions in parent
529 Because you can specify an absolute path to the parent action, it
530 doesn't matter to Catalyst where that parent is located. So, if your
531 design requests it, you can redispatch a chain through any controller or
534 Another interesting possibility gives C<:Chained('.')>, which chains
535 itself to an action with the path of the current controller's namespace.
538 # in MyApp::Controller::Foo
539 sub bar : Chained CaptureArgs(1) { ... }
541 # in MyApp::Controller::Foo::Bar
542 sub baz : Chained('.') Args(1) { ... }
544 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
545 as the argument to Chained here chains the C<baz> action to an action
546 with the path of the current controller namespace, namely
547 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
548 chain comes out as the end product.
552 Chains an action to another action with the same name in the parent
553 controller. For Example:
555 # in MyApp::Controller::Foo
556 sub bar : Chained CaptureArgs(1) { ... }
558 # in MyApp::Controller::Foo::Moo
559 sub bar : ChainedParent Args(1) { ... }
561 This builds a chain like C</bar/*/bar/*>.
565 Must be specified for every part of the chain that is not an
566 endpoint. With this attribute Catalyst knows how many of the following
567 parts of the path (separated by C</>) this action wants to capture as
568 its arguments. If it doesn't expect any, just specify
569 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
570 after the context, but you can also find them as array references in
571 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
572 level of the action in the chain that captured the parts of the path.
574 An action that is part of a chain (that is, one that has a C<:Chained>
575 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
580 By default, endpoints receive the rest of the arguments in the path. You
581 can tell Catalyst through C<:Args> explicitly how many arguments your
582 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
583 also affects whether this chain is invoked on a request. A chain with an
584 endpoint specifying one argument will only match if exactly one argument
587 You can specify an exact number of arguments like C<:Args(3)>, including
588 C<0>. If you just say C<:Args> without any arguments, it is the same as
589 leaving it out altogether: The chain is matched regardless of the number
590 of path parts after the endpoint.
592 Just as with C<:CaptureArgs>, the arguments get passed to the action in
593 C<@_> after the context object. They can also be reached through
594 C<$c-E<gt>request-E<gt>arguments>.
598 =head2 Auto actions, dispatching and forwarding
600 Note that the list of C<auto> actions called depends on the private path
601 of the endpoint of the chain, not on the chained actions way. The
602 C<auto> actions will be run before the chain dispatching begins. In
603 every other aspect, C<auto> actions behave as documented.
605 The C<forward>ing to other actions does just what you would expect. But if
606 you C<detach> out of a chain, the rest of the chain will not get called
611 Catalyst Contributors, see Catalyst.pm
615 This program is free software, you can redistribute it and/or modify it under
616 the same terms as Perl itself.