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 ($parent !~ m/^\//) {
195 if ($action->namespace) {
196 $parent = '/'.join('/', $action->namespace, $parent);
198 $parent = '/'.$parent; # special case namespace '' (root)
205 $action->attributes->{Chained} = [ $parent ];
207 my $children = ($self->{children_of}{$parent} ||= {});
209 my @path_part = @{ $action->attributes->{PathPart} || [] };
211 my $part = $action->name;
213 if (@path_part == 1 && defined $path_part[0]) {
214 $part = $path_part[0];
215 } elsif (@path_part > 1) {
216 Catalyst::Exception->throw(
217 "Multiple PathPart attributes not supported registering ${action}"
221 if ($part =~ m(^/)) {
222 Catalyst::Exception->throw(
223 "Absolute parameters to PathPart not allowed registering ${action}"
227 $action->attributes->{PartPath} = [ $part ];
229 unshift(@{ $children->{$part} ||= [] }, $action);
231 ($self->{actions} ||= {})->{'/'.$action->reverse} = $action;
233 unless ($action->attributes->{CaptureArgs}) {
234 unshift(@{ $self->{endpoints} ||= [] }, $action);
240 =head2 $self->uri_for_action($action, $captures)
242 Get the URI part for the action, using C<$captures> to fill
248 my ( $self, $action, $captures ) = @_;
250 return undef unless ($action->attributes->{Chained}
251 && !$action->attributes->{CaptureArgs});
254 my @captures = @$captures;
255 my $parent = "DUMMY";
258 if (my $cap = $curr->attributes->{CaptureArgs}) {
259 return undef unless @captures >= $cap->[0]; # not enough captures
261 unshift(@parts, splice(@captures, -$cap->[0]));
264 if (my $pp = $curr->attributes->{PartPath}) {
265 unshift(@parts, $pp->[0])
266 if (defined($pp->[0]) && length($pp->[0]));
268 $parent = $curr->attributes->{Chained}->[0];
269 $curr = $self->{actions}{$parent};
272 return undef unless $parent eq '/'; # fail for dangling action
274 return undef if @captures; # fail for too many captures
276 return join('/', '', @parts);
284 The C<Chained> attribute allows you to chain public path parts together
285 by their private names. A chain part's path can be specified with
286 C<PathPart> and can be declared to expect an arbitrary number of
287 arguments. The endpoint of the chain specifies how many arguments it
288 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
289 C<:Args> without an integer would be unlimited. The path parts that
290 aren't endpoints are using C<CaptureArgs> to specify how many parameters
291 they expect to receive. As an example setup:
293 package MyApp::Controller::Greeting;
294 use base qw/ Catalyst::Controller /;
296 # this is the beginning of our chain
297 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
298 my ( $self, $c, $integer ) = @_;
299 $c->stash->{ message } = "Hello ";
300 $c->stash->{ arg_sum } = $integer;
303 # this is our endpoint, because it has no :CaptureArgs
304 sub world : PathPart('world') Chained('hello') Args(1) {
305 my ( $self, $c, $integer ) = @_;
306 $c->stash->{ message } .= "World!";
307 $c->stash->{ arg_sum } += $integer;
309 $c->response->body( join "<br/>\n" =>
310 $c->stash->{ message }, $c->stash->{ arg_sum } );
313 The debug output provides a separate table for chained actions, showing
314 the whole chain as it would match and the actions it contains. Here's an
315 example of the startup output with our actions above:
318 [debug] Loaded Path Part actions:
319 .-----------------------+------------------------------.
320 | Path Spec | Private |
321 +-----------------------+------------------------------+
322 | /hello/*/world/* | /greeting/hello (1) |
323 | | => /greeting/world |
324 '-----------------------+------------------------------'
327 As you can see, Catalyst only deals with chains as whole paths and
328 builds one for each endpoint, which are the actions with C<:Chained> but
329 without C<:CaptureArgs>.
331 Let's assume this application gets a request at the path
332 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
333 to the C<hello> action and pass the value C<23> as an argument to it
334 after the context. It does so because we have previously used
335 C<:CaptureArgs(1)> to declare that it has one path part after itself as
336 its argument. We told Catalyst that this is the beginning of the chain
337 by specifying C<:Chained('/')>. Also note that instead of saying
338 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
339 defaults to the name of the action.
341 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
342 action. This is the last action to be called: Catalyst knows this is an
343 endpoint because we did not specify a C<:CaptureArgs>
344 attribute. Nevertheless we specify that this action expects an argument,
345 but at this point we're using C<:Args(1)> to do that. We could also have
346 said C<:Args> or left it out altogether, which would mean this action
347 would get all arguments that are there. This action's C<:Chained>
348 attribute says C<hello> and tells Catalyst that the C<hello> action in
349 the current controller is its parent.
351 With this we have built a chain consisting of two public path parts.
352 C<hello> captures one part of the path as its argument, and also
353 specifies the path root as its parent. So this part is
354 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
355 argument. It sums up to the path part C<world/$arg>. This leads to a
356 complete chain of C</hello/$arg/world/$arg> which is matched against the
359 This example application would, if run and called by e.g.
360 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
361 value C<arg_sum> to "23". The C<world> action would then append "World!"
362 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
363 sake of simplicity no view is shown. Instead we just put the values of
364 the stash into our body. So the output would look like:
369 And our test server would have given us this debugging output for the
373 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
374 [debug] Path is "/greeting/world"
375 [debug] Arguments are "12"
376 [info] Request took 0.164113s (6.093/s)
377 .------------------------------------------+-----------.
379 +------------------------------------------+-----------+
380 | /greeting/hello | 0.000029s |
381 | /greeting/world | 0.000024s |
382 '------------------------------------------+-----------'
385 What would be common uses of this dispatch technique? It gives the
386 possibility to split up logic that contains steps that each depend on
387 each other. An example would be, for example, a wiki path like
388 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
391 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
392 my ( $self, $c, $page_name ) = @_;
393 # load the page named $page_name and put the object
397 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
398 my ( $self, $c, $revision_id ) = @_;
399 # use the page object in the stash to get at its
400 # revision with number $revision_id
403 sub view : PathPart Chained('rev') Args(0) {
404 my ( $self, $c ) = @_;
405 # display the revision in our stash. Another option
406 # would be to forward a compatible object to the action
407 # that displays the default wiki pages, unless we want
408 # a different interface here, for example restore
412 It would now be possible to add other endpoints, for example C<restore>
413 to restore this specific revision as the current state.
415 You don't have to put all the chained actions in one controller. The
416 specification of the parent through C<:Chained> also takes an absolute
417 action path as its argument. Just specify it with a leading C</>.
419 If you want, for example, to have actions for the public paths
420 C</foo/12/edit> and C</foo/12>, just specify two actions with
421 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
422 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
423 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
424 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
425 this debugging output:
428 [debug] Loaded Path Part actions:
429 .-----------------------+------------------------------.
430 | Path Spec | Private |
431 +-----------------------+------------------------------+
432 | /foo/* | /controller/foo_view |
433 | /foo/*/edit | /controller/foo_load (1) |
434 | | => /controller/edit |
435 '-----------------------+------------------------------'
438 Here's a more detailed specification of the attributes belonging to
447 Sets the name of this part of the chain. If it is specified without
448 arguments, it takes the name of the action as default. So basically
449 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
450 This can also contain slashes to bind to a deeper level. An action
451 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
452 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
453 effect as using C<:PathPart>, it would default to the action name.
457 Has to be specified for every child in the chain. Possible values are
458 absolute and relative private action paths, with the relatives pointing
459 to the current controller, or a single slash C</> to tell Catalyst that
460 this is the root of a chain. The attribute C<:Chained> without aguments
461 also defaults to the C</> behavior.
463 Because you can specify an absolute path to the parent action, it
464 doesn't matter to Catalyst where that parent is located. So, if your
465 design requests it, you can redispatch a chain through any controller or
468 Another interesting possibility gives C<:Chained('.')>, which chains
469 itself to an action with the path of the current controller's namespace.
472 # in MyApp::Controller::Foo
473 sub bar : Chained CaptureArgs(1) { ... }
475 # in MyApp::Controller::Foo::Bar
476 sub baz : Chained('.') Args(1) { ... }
478 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
479 as the argument to Chained here chains the C<baz> action to an action
480 with the path of the current controller namespace, namely
481 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
482 chain comes out as the end product.
486 Must be specified for every part of the chain that is not an
487 endpoint. With this attribute Catalyst knows how many of the following
488 parts of the path (separated by C</>) this action wants to capture as
489 its arguments. If it doesn't expect any, just specify
490 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
491 after the context, but you can also find them as array references in
492 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
493 level of the action in the chain that captured the parts of the path.
495 An action that is part of a chain (that is, one that has a C<:Chained>
496 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
501 By default, endpoints receive the rest of the arguments in the path. You
502 can tell Catalyst through C<:Args> explicitly how many arguments your
503 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
504 also affects whether this chain is invoked on a request. A chain with an
505 endpoint specifying one argument will only match if exactly one argument
508 You can specify an exact number of arguments like C<:Args(3)>, including
509 C<0>. If you just say C<:Args> without any arguments, it is the same as
510 leaving it out altogether: The chain is matched regardless of the number
511 of path parts after the endpoint.
513 Just as with C<:CaptureArgs>, the arguments get passed to the action in
514 C<@_> after the context object. They can also be reached through
515 C<$c-E<gt>request-E<gt>arguments>.
519 =head2 Auto actions, dispatching and forwarding
521 Note that the list of C<auto> actions called depends on the private path
522 of the endpoint of the chain, not on the chained actions way. The
523 C<auto> actions will be run before the chain dispatching begins. In
524 every other aspect, C<auto> actions behave as documented.
526 The C<forward>ing to other actions does just what you would expect. But if
527 you C<detach> out of a chain, the rest of the chain will not get called
532 Matt S Trout <mst@shadowcatsystems.co.uk>
536 This program is free software, you can redistribute it and/or modify it under
537 the same terms as Perl itself.