1 package Catalyst::DispatchType::Chained;
4 use base qw/Catalyst::DispatchType/;
6 use Catalyst::ActionChain;
9 # please don't perltidy this. hairy code within.
13 Catalyst::DispatchType::Chained - Path Part DispatchType
17 # root action - captures one argument after it
18 sub foo_setup : Chained('/') PathPart('foo') CaptureArgs(1) {
19 my ( $self, $c, $foo_arg ) = @_;
23 # child action endpoint - takes one argument
24 sub bar : Chained('foo_setup') Args(1) {
25 my ( $self, $c, $bar_arg ) = @_;
35 =head2 $self->list($c)
37 Debug output for Path Part dispatch points
42 my ( $self, $c ) = @_;
44 return unless $self->{endpoints};
46 my $paths = Text::SimpleTable->new(
47 [ 35, 'Path Spec' ], [ 36, 'Private' ]
50 ENDPOINT: foreach my $endpoint (
51 sort { $a->reverse cmp $b->reverse }
52 @{ $self->{endpoints} }
54 my $args = $endpoint->attributes->{Args}->[0];
55 my @parts = (defined($args) ? (("*") x $args) : '...');
60 if (my $cap = $curr->attributes->{CaptureArgs}) {
61 unshift(@parts, (("*") x $cap->[0]));
63 if (my $pp = $curr->attributes->{PartPath}) {
64 unshift(@parts, $pp->[0])
65 if (defined $pp->[0] && length $pp->[0]);
67 $parent = $curr->attributes->{Chained}->[0];
68 $curr = $self->{actions}{$parent};
69 unshift(@parents, $curr) if $curr;
71 next ENDPOINT unless $parent eq '/'; # skip dangling action
73 foreach my $p (@parents) {
75 if (my $cap = $p->attributes->{CaptureArgs}) {
76 $name .= ' ('.$cap->[0].')';
78 unless ($p eq $parents[0]) {
81 push(@rows, [ '', $name ]);
83 push(@rows, [ '', (@rows ? "=> " : '')."/${endpoint}" ]);
84 $rows[0][0] = join('/', '', @parts);
85 $paths->row(@$_) for @rows;
88 $c->log->debug( "Loaded Path Part actions:\n" . $paths->draw );
91 =head2 $self->match( $c, $path )
93 Calls C<recurse_match> to see if a chain matches the C<$path>.
98 my ( $self, $c, $path ) = @_;
100 return 0 if @{$c->req->args};
102 my @parts = split('/', $path);
104 my ($chain, $captures) = $self->recurse_match($c, '/', \@parts);
106 return 0 unless $chain;
108 my $action = Catalyst::ActionChain->from_chain($chain);
110 $c->req->action("/${action}");
111 $c->req->match("/${action}");
112 $c->req->captures($captures);
114 $c->namespace( $action->namespace );
119 =head2 $self->recurse_match( $c, $parent, \@path_parts )
121 Recursive search for a matching chain.
126 my ( $self, $c, $parent, $path_parts ) = @_;
127 my $children = $self->{children_of}{$parent};
128 return () unless $children;
130 TRY: foreach my $try_part (sort { length($b) <=> length($a) }
132 # $b then $a to try longest part first
133 my @parts = @$path_parts;
134 if (length $try_part) { # test and strip PathPart
136 ($try_part eq join('/', # assemble equal number of parts
137 splice( # and strip them off @parts as well
138 @parts, 0, scalar(@{[split('/', $try_part)]})
139 ))); # @{[]} to avoid split to @_
141 my @try_actions = @{$children->{$try_part}};
142 TRY_ACTION: foreach my $action (@try_actions) {
143 if (my $capture_attr = $action->attributes->{CaptureArgs}) {
145 my @parts = @parts; # localise
147 # strip CaptureArgs into list
148 push(@captures, splice(@parts, 0, $capture_attr->[0]));
150 # try the remaining parts against children of this action
151 my ($actions, $captures) = $self->recurse_match(
152 $c, '/'.$action->reverse, \@parts
155 return [ $action, @$actions ], [ @captures, @$captures ];
159 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
160 next TRY_ACTION unless $action->match($c);
162 push(@{$c->req->args}, @parts);
163 return [ $action ], [ ];
170 =head2 $self->register( $c, $action )
172 Calls register_path for every Path attribute for the given $action.
177 my ( $self, $c, $action ) = @_;
179 my @chained_attr = @{ $action->attributes->{Chained} || [] };
181 return 0 unless @chained_attr;
183 if (@chained_attr > 2) {
184 Catalyst::Exception->throw(
185 "Multiple Chained attributes not supported registering ${action}"
189 my $parent = $chained_attr[0];
191 if (defined($parent) && length($parent)) {
192 if ($parent eq '.') {
193 $parent = '/'.$action->namespace;
194 } elsif ($parent !~ m/^\//) {
195 $parent = '/'.join('/', $action->namespace, $parent);
201 $action->attributes->{Chained} = [ $parent ];
203 my $children = ($self->{children_of}{$parent} ||= {});
205 my @path_part = @{ $action->attributes->{PathPart} || [] };
207 my $part = $action->name;
209 if (@path_part == 1 && defined $path_part[0]) {
210 $part = $path_part[0];
211 } elsif (@path_part > 1) {
212 Catalyst::Exception->throw(
213 "Multiple PathPart attributes not supported registering ${action}"
217 if ($part =~ m(^/)) {
218 Catalyst::Exception->throw(
219 "Absolute parameters to PathPart not allowed registering ${action}"
223 $action->attributes->{PartPath} = [ $part ];
225 unshift(@{ $children->{$part} ||= [] }, $action);
227 ($self->{actions} ||= {})->{'/'.$action->reverse} = $action;
229 unless ($action->attributes->{CaptureArgs}) {
230 unshift(@{ $self->{endpoints} ||= [] }, $action);
236 =head2 $self->uri_for_action($action, $captures)
238 Get the URI part for the action, using C<$captures> to fill
244 my ( $self, $action, $captures ) = @_;
246 return undef unless ($action->attributes->{Chained}
247 && $action->attributes->{Args});
250 my @captures = @$captures;
251 my $parent = "DUMMY";
254 if (my $cap = $curr->attributes->{CaptureArgs}) {
255 return undef unless @captures >= $cap->[0]; # not enough captures
256 unshift(@parts, splice(@captures, -$cap->[0]));
258 if (my $pp = $curr->attributes->{PartPath}) {
259 unshift(@parts, $pp->[0])
260 if (defined $pp->[0] && length $pp->[0]);
262 $parent = $curr->attributes->{Chained}->[0];
263 $curr = $self->{actions}{$parent};
266 return undef unless $parent eq '/'; # fail for dangling action
268 return undef if @captures; # fail for too many captures
270 return join('/', '', @parts);
278 The C<Chained> attribute allows you to chain public path parts together
279 by their private names. A chain part's path can be specified with
280 C<PathPart> and can be declared to expect an arbitrary number of
281 arguments. The endpoint of the chain specifies how many arguments it
282 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
283 C<:Args> without an integer would be unlimited. The path parts that
284 aren't endpoints are using C<CaptureArgs> to specify how many parameters
285 they expect to receive. As an example setup:
287 package MyApp::Controller::Greeting;
288 use base qw/ Catalyst::Controller /;
290 # this is the beginning of our chain
291 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
292 my ( $self, $c, $integer ) = @_;
293 $c->stash->{ message } = "Hello ";
294 $c->stash->{ arg_sum } = $integer;
297 # this is our endpoint, because it has no :CaptureArgs
298 sub world : PathPart('world') Chained('hello') Args(1) {
299 my ( $self, $c, $integer ) = @_;
300 $c->stash->{ message } .= "World!";
301 $c->stash->{ arg_sum } += $integer;
303 $c->response->body( join "<br/>\n" =>
304 $c->stash->{ message }, $c->stash->{ arg_sum } );
307 The debug output provides a separate table for chained actions, showing
308 the whole chain as it would match and the actions it contains. Here's an
309 example of the startup output with our actions above:
312 [debug] Loaded Path Part actions:
313 .-----------------------+------------------------------.
314 | Path Spec | Private |
315 +-----------------------+------------------------------+
316 | /hello/*/world/* | /greeting/hello (1) |
317 | | => /greeting/world |
318 '-----------------------+------------------------------'
321 As you can see, Catalyst only deals with chains as whole paths and
322 builds one for each endpoint, which are the actions with C<:Chained> but
323 without C<:CaptureArgs>.
325 Let's assume this application gets a request at the path
326 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
327 to the C<hello> action and pass the value C<23> as an argument to it
328 after the context. It does so because we have previously used
329 C<:CaptureArgs(1)> to declare that it has one path part after itself as
330 its argument. We told Catalyst that this is the beginning of the chain
331 by specifying C<:Chained('/')>. Also note that instead of saying
332 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
333 defaults to the name of the action.
335 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
336 action. This is the last action to be called: Catalyst knows this is an
337 endpoint because we did not specify a C<:CaptureArgs>
338 attribute. Nevertheless we specify that this action expects an argument,
339 but at this point we're using C<:Args(1)> to do that. We could also have
340 said C<:Args> or left it out altogether, which would mean this action
341 would get all arguments that are there. This action's C<:Chained>
342 attribute says C<hello> and tells Catalyst that the C<hello> action in
343 the current controller is its parent.
345 With this we have built a chain consisting of two public path parts.
346 C<hello> captures one part of the path as its argument, and also
347 specifies the path root as its parent. So this part is
348 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
349 argument. It sums up to the path part C<world/$arg>. This leads to a
350 complete chain of C</hello/$arg/world/$arg> which is matched against the
353 This example application would, if run and called by e.g.
354 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
355 value C<arg_sum> to "23". The C<world> action would then append "World!"
356 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
357 sake of simplicity no view is shown. Instead we just put the values of
358 the stash into our body. So the output would look like:
363 And our test server would have given us this debugging output for the
367 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
368 [debug] Path is "/greeting/world"
369 [debug] Arguments are "12"
370 [info] Request took 0.164113s (6.093/s)
371 .------------------------------------------+-----------.
373 +------------------------------------------+-----------+
374 | /greeting/hello | 0.000029s |
375 | /greeting/world | 0.000024s |
376 '------------------------------------------+-----------'
379 What would be common uses of this dispatch technique? It gives the
380 possibility to split up logic that contains steps that each depend on
381 each other. An example would be, for example, a wiki path like
382 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
385 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
386 my ( $self, $c, $page_name ) = @_;
387 # load the page named $page_name and put the object
391 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
392 my ( $self, $c, $revision_id ) = @_;
393 # use the page object in the stash to get at its
394 # revision with number $revision_id
397 sub view : PathPart Chained('rev') Args(0) {
398 my ( $self, $c ) = @_;
399 # display the revision in our stash. Another option
400 # would be to forward a compatible object to the action
401 # that displays the default wiki pages, unless we want
402 # a different interface here, for example restore
406 It would now be possible to add other endpoints, for example C<restore>
407 to restore this specific revision as the current state.
409 You don't have to put all the chained actions in one controller. The
410 specification of the parent through C<:Chained> also takes an absolute
411 action path as its argument. Just specify it with a leading C</>.
413 If you want, for example, to have actions for the public paths
414 C</foo/12/edit> and C</foo/12>, just specify two actions with
415 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
416 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
417 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
418 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
419 this debugging output:
422 [debug] Loaded Path Part actions:
423 .-----------------------+------------------------------.
424 | Path Spec | Private |
425 +-----------------------+------------------------------+
426 | /foo/* | /controller/foo_view |
427 | /foo/*/edit | /controller/foo_load (1) |
428 | | => /controller/edit |
429 '-----------------------+------------------------------'
432 Here's a more detailed specification of the attributes belonging to
441 Sets the name of this part of the chain. If it is specified without
442 arguments, it takes the name of the action as default. So basically
443 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
444 This can also contain slashes to bind to a deeper level. An action
445 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
446 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
447 effect as using C<:PathPart>, it would default to the action name.
451 Has to be specified for every child in the chain. Possible values are
452 absolute and relative private action paths, with the relatives pointing
453 to the current controller, or a single slash C</> to tell Catalyst that
454 this is the root of a chain. The attribute C<:Chained> without aguments
455 also defaults to the C</> behavior.
457 Because you can specify an absolute path to the parent action, it
458 doesn't matter to Catalyst where that parent is located. So, if your
459 design requests it, you can redispatch a chain through any controller or
462 Another interesting possibility gives C<:Chained('.')>, which chains
463 itself to an action with the path of the current controller's namespace.
466 # in MyApp::Controller::Foo
467 sub bar : Chained CaptureArgs(1) { ... }
469 # in MyApp::Controller::Foo::Bar
470 sub baz : Chained('.') Args(1) { ... }
472 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
473 as the argument to Chained here chains the C<baz> action to an action
474 with the path of the current controller namespace, namely
475 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
476 chain comes out as the end product.
480 Must be specified for every part of the chain that is not an
481 endpoint. With this attribute Catalyst knows how many of the following
482 parts of the path (separated by C</>) this action wants to capture as
483 its arguments. If it doesn't expect any, just specify
484 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
485 after the context, but you can also find them as array references in
486 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
487 level of the action in the chain that captured the parts of the path.
489 An action that is part of a chain (that is, one that has a C<:Chained>
490 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
495 By default, endpoints receive the rest of the arguments in the path. You
496 can tell Catalyst through C<:Args> explicitly how many arguments your
497 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
498 also affects whether this chain is invoked on a request. A chain with an
499 endpoint specifying one argument will only match if exactly one argument
502 You can specify an exact number of arguments like C<:Args(3)>, including
503 C<0>. If you just say C<:Args> without any arguments, it is the same as
504 leaving it out altogether: The chain is matched regardless of the number
505 of path parts after the endpoint.
507 Just as with C<:CaptureArgs>, the arguments get passed to the action in
508 C<@_> after the context object. They can also be reached through
509 C<$c-E<gt>request-E<gt>arguments>.
513 =head2 Auto actions, dispatching and forwarding
515 Note that the list of C<auto> actions called depends on the private path
516 of the endpoint of the chain, not on the chained actions way. The
517 C<auto> actions will be run before the chain dispatching begins. In
518 every other aspect, C<auto> actions behave as documented.
520 The C<forward>ing to other actions does just what you would expect. But if
521 you C<detach> out of a chain, the rest of the chain will not get called
526 Matt S Trout <mst@shadowcatsystems.co.uk>
530 This program is free software, you can redistribute it and/or modify it under
531 the same terms as Perl itself.