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 if ($actions && (!$best_action || $#$action_parts < $#{$best_action->{parts}})){
187 actions => [ $action, @$actions ],
188 captures=> [ @captures, @$captures ],
189 parts => $action_parts
195 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
196 next TRY_ACTION unless $action->match($c);
198 my $args_attr = $action->attributes->{Args}->[0];
200 # No best action currently
201 # OR This one matches with fewer parts left than the current best action,
202 # And therefore is a better match
203 # OR No parts and this expects 0
204 # The current best action might also be Args(0),
205 # but we couldn't chose between then anyway so we'll take the last seen
208 @parts < @{$best_action->{parts}} ||
209 (!@parts && $args_attr eq 0)){
211 actions => [ $action ],
219 return @$best_action{qw/actions captures parts/} if $best_action;
223 =head2 $self->register( $c, $action )
225 Calls register_path for every Path attribute for the given $action.
230 my ( $self, $c, $action ) = @_;
232 my @chained_attr = @{ $action->attributes->{Chained} || [] };
234 return 0 unless @chained_attr;
236 if (@chained_attr > 2) {
237 Catalyst::Exception->throw(
238 "Multiple Chained attributes not supported registering ${action}"
242 my $parent = $chained_attr[0];
244 if (defined($parent) && length($parent)) {
245 if ($parent eq '.') {
246 $parent = '/'.$action->namespace;
247 } elsif ($parent !~ m/^\//) {
248 if ($action->namespace) {
249 $parent = '/'.join('/', $action->namespace, $parent);
251 $parent = '/'.$parent; # special case namespace '' (root)
258 $action->attributes->{Chained} = [ $parent ];
260 my $children = ($self->_children_of->{$parent} ||= {});
262 my @path_part = @{ $action->attributes->{PathPart} || [] };
264 my $part = $action->name;
266 if (@path_part == 1 && defined $path_part[0]) {
267 $part = $path_part[0];
268 } elsif (@path_part > 1) {
269 Catalyst::Exception->throw(
270 "Multiple PathPart attributes not supported registering " . $action->reverse()
274 if ($part =~ m(^/)) {
275 Catalyst::Exception->throw(
276 "Absolute parameters to PathPart not allowed registering " . $action->reverse()
280 $action->attributes->{PartPath} = [ $part ];
282 unshift(@{ $children->{$part} ||= [] }, $action);
284 $self->_actions->{'/'.$action->reverse} = $action;
286 unless ($action->attributes->{CaptureArgs}) {
287 unshift(@{ $self->_endpoints }, $action);
293 =head2 $self->uri_for_action($action, $captures)
295 Get the URI part for the action, using C<$captures> to fill
301 my ( $self, $action, $captures ) = @_;
303 return undef unless ($action->attributes->{Chained}
304 && !$action->attributes->{CaptureArgs});
307 my @captures = @$captures;
308 my $parent = "DUMMY";
311 if (my $cap = $curr->attributes->{CaptureArgs}) {
312 return undef unless @captures >= $cap->[0]; # not enough captures
314 unshift(@parts, splice(@captures, -$cap->[0]));
317 if (my $pp = $curr->attributes->{PartPath}) {
318 unshift(@parts, $pp->[0])
319 if (defined($pp->[0]) && length($pp->[0]));
321 $parent = $curr->attributes->{Chained}->[0];
322 $curr = $self->_actions->{$parent};
325 return undef unless $parent eq '/'; # fail for dangling action
327 return undef if @captures; # fail for too many captures
329 return join('/', '', @parts);
333 __PACKAGE__->meta->make_immutable;
339 The C<Chained> attribute allows you to chain public path parts together
340 by their private names. A chain part's path can be specified with
341 C<PathPart> and can be declared to expect an arbitrary number of
342 arguments. The endpoint of the chain specifies how many arguments it
343 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
344 C<:Args> without an integer would be unlimited. The path parts that
345 aren't endpoints are using C<CaptureArgs> to specify how many parameters
346 they expect to receive. As an example setup:
348 package MyApp::Controller::Greeting;
349 use base qw/ Catalyst::Controller /;
351 # this is the beginning of our chain
352 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
353 my ( $self, $c, $integer ) = @_;
354 $c->stash->{ message } = "Hello ";
355 $c->stash->{ arg_sum } = $integer;
358 # this is our endpoint, because it has no :CaptureArgs
359 sub world : PathPart('world') Chained('hello') Args(1) {
360 my ( $self, $c, $integer ) = @_;
361 $c->stash->{ message } .= "World!";
362 $c->stash->{ arg_sum } += $integer;
364 $c->response->body( join "<br/>\n" =>
365 $c->stash->{ message }, $c->stash->{ arg_sum } );
368 The debug output provides a separate table for chained actions, showing
369 the whole chain as it would match and the actions it contains. Here's an
370 example of the startup output with our actions above:
373 [debug] Loaded Path Part actions:
374 .-----------------------+------------------------------.
375 | Path Spec | Private |
376 +-----------------------+------------------------------+
377 | /hello/*/world/* | /greeting/hello (1) |
378 | | => /greeting/world |
379 '-----------------------+------------------------------'
382 As you can see, Catalyst only deals with chains as whole paths and
383 builds one for each endpoint, which are the actions with C<:Chained> but
384 without C<:CaptureArgs>.
386 Let's assume this application gets a request at the path
387 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
388 to the C<hello> action and pass the value C<23> as an argument to it
389 after the context. It does so because we have previously used
390 C<:CaptureArgs(1)> to declare that it has one path part after itself as
391 its argument. We told Catalyst that this is the beginning of the chain
392 by specifying C<:Chained('/')>. Also note that instead of saying
393 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
394 defaults to the name of the action.
396 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
397 action. This is the last action to be called: Catalyst knows this is an
398 endpoint because we did not specify a C<:CaptureArgs>
399 attribute. Nevertheless we specify that this action expects an argument,
400 but at this point we're using C<:Args(1)> to do that. We could also have
401 said C<:Args> or left it out altogether, which would mean this action
402 would get all arguments that are there. This action's C<:Chained>
403 attribute says C<hello> and tells Catalyst that the C<hello> action in
404 the current controller is its parent.
406 With this we have built a chain consisting of two public path parts.
407 C<hello> captures one part of the path as its argument, and also
408 specifies the path root as its parent. So this part is
409 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
410 argument. It sums up to the path part C<world/$arg>. This leads to a
411 complete chain of C</hello/$arg/world/$arg> which is matched against the
414 This example application would, if run and called by e.g.
415 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
416 value C<arg_sum> to "23". The C<world> action would then append "World!"
417 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
418 sake of simplicity no view is shown. Instead we just put the values of
419 the stash into our body. So the output would look like:
424 And our test server would have given us this debugging output for the
428 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
429 [debug] Path is "/greeting/world"
430 [debug] Arguments are "12"
431 [info] Request took 0.164113s (6.093/s)
432 .------------------------------------------+-----------.
434 +------------------------------------------+-----------+
435 | /greeting/hello | 0.000029s |
436 | /greeting/world | 0.000024s |
437 '------------------------------------------+-----------'
440 What would be common uses of this dispatch technique? It gives the
441 possibility to split up logic that contains steps that each depend on
442 each other. An example would be, for example, a wiki path like
443 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
446 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
447 my ( $self, $c, $page_name ) = @_;
448 # load the page named $page_name and put the object
452 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
453 my ( $self, $c, $revision_id ) = @_;
454 # use the page object in the stash to get at its
455 # revision with number $revision_id
458 sub view : PathPart Chained('rev') Args(0) {
459 my ( $self, $c ) = @_;
460 # display the revision in our stash. Another option
461 # would be to forward a compatible object to the action
462 # that displays the default wiki pages, unless we want
463 # a different interface here, for example restore
467 It would now be possible to add other endpoints, for example C<restore>
468 to restore this specific revision as the current state.
470 You don't have to put all the chained actions in one controller. The
471 specification of the parent through C<:Chained> also takes an absolute
472 action path as its argument. Just specify it with a leading C</>.
474 If you want, for example, to have actions for the public paths
475 C</foo/12/edit> and C</foo/12>, just specify two actions with
476 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
477 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
478 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
479 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
480 this debugging output:
483 [debug] Loaded Path Part actions:
484 .-----------------------+------------------------------.
485 | Path Spec | Private |
486 +-----------------------+------------------------------+
487 | /foo/* | /controller/foo_view |
488 | /foo/*/edit | /controller/foo_load (1) |
489 | | => /controller/edit |
490 '-----------------------+------------------------------'
493 Here's a more detailed specification of the attributes belonging to
502 Sets the name of this part of the chain. If it is specified without
503 arguments, it takes the name of the action as default. So basically
504 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
505 This can also contain slashes to bind to a deeper level. An action
506 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
507 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
508 effect as using C<:PathPart>, it would default to the action name.
512 Has to be specified for every child in the chain. Possible values are
513 absolute and relative private action paths, with the relatives pointing
514 to the current controller, or a single slash C</> to tell Catalyst that
515 this is the root of a chain. The attribute C<:Chained> without arguments
516 also defaults to the C</> behavior.
518 Because you can specify an absolute path to the parent action, it
519 doesn't matter to Catalyst where that parent is located. So, if your
520 design requests it, you can redispatch a chain through any controller or
523 Another interesting possibility gives C<:Chained('.')>, which chains
524 itself to an action with the path of the current controller's namespace.
527 # in MyApp::Controller::Foo
528 sub bar : Chained CaptureArgs(1) { ... }
530 # in MyApp::Controller::Foo::Bar
531 sub baz : Chained('.') Args(1) { ... }
533 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
534 as the argument to Chained here chains the C<baz> action to an action
535 with the path of the current controller namespace, namely
536 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
537 chain comes out as the end product.
541 Must be specified for every part of the chain that is not an
542 endpoint. With this attribute Catalyst knows how many of the following
543 parts of the path (separated by C</>) this action wants to capture as
544 its arguments. If it doesn't expect any, just specify
545 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
546 after the context, but you can also find them as array references in
547 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
548 level of the action in the chain that captured the parts of the path.
550 An action that is part of a chain (that is, one that has a C<:Chained>
551 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
556 By default, endpoints receive the rest of the arguments in the path. You
557 can tell Catalyst through C<:Args> explicitly how many arguments your
558 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
559 also affects whether this chain is invoked on a request. A chain with an
560 endpoint specifying one argument will only match if exactly one argument
563 You can specify an exact number of arguments like C<:Args(3)>, including
564 C<0>. If you just say C<:Args> without any arguments, it is the same as
565 leaving it out altogether: The chain is matched regardless of the number
566 of path parts after the endpoint.
568 Just as with C<:CaptureArgs>, the arguments get passed to the action in
569 C<@_> after the context object. They can also be reached through
570 C<$c-E<gt>request-E<gt>arguments>.
574 =head2 Auto actions, dispatching and forwarding
576 Note that the list of C<auto> actions called depends on the private path
577 of the endpoint of the chain, not on the chained actions way. The
578 C<auto> actions will be run before the chain dispatching begins. In
579 every other aspect, C<auto> actions behave as documented.
581 The C<forward>ing to other actions does just what you would expect. But if
582 you C<detach> out of a chain, the rest of the chain will not get called
587 Matt S Trout <mst@shadowcatsystems.co.uk>
591 This program is free software, you can redistribute it and/or modify it under
592 the same terms as Perl itself.