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 Chained actions:\n" . $paths->draw . "\n" );
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, $parts) = $self->recurse_match($c, '/', \@parts);
105 push @{$c->req->args}, @$parts if $parts && @$parts;
107 return 0 unless $chain;
109 my $action = Catalyst::ActionChain->from_chain($chain);
111 $c->req->action("/${action}");
112 $c->req->match("/${action}");
113 $c->req->captures($captures);
115 $c->namespace( $action->namespace );
120 =head2 $self->recurse_match( $c, $parent, \@path_parts )
122 Recursive search for a matching chain.
127 my ( $self, $c, $parent, $path_parts ) = @_;
128 my $children = $self->{children_of}{$parent};
129 return () unless $children;
132 TRY: foreach my $try_part (sort { length($b) <=> length($a) }
134 # $b then $a to try longest part first
135 my @parts = @$path_parts;
136 if (length $try_part) { # test and strip PathPart
138 ($try_part eq join('/', # assemble equal number of parts
139 splice( # and strip them off @parts as well
140 @parts, 0, scalar(@{[split('/', $try_part)]})
141 ))); # @{[]} to avoid split to @_
143 my @try_actions = @{$children->{$try_part}};
144 TRY_ACTION: foreach my $action (@try_actions) {
145 if (my $capture_attr = $action->attributes->{CaptureArgs}) {
147 # Short-circuit if not enough remaining parts
148 next TRY_ACTION unless @parts >= $capture_attr->[0];
151 my @parts = @parts; # localise
153 # strip CaptureArgs into list
154 push(@captures, splice(@parts, 0, $capture_attr->[0]));
156 # try the remaining parts against children of this action
157 my ($actions, $captures, $action_parts) = $self->recurse_match(
158 $c, '/'.$action->reverse, \@parts
160 # No best action currently
161 # OR The action has less parts
162 # OR The action has equal parts but less captured data (ergo more defined)
165 $#$action_parts < $#{$best_action->{parts}} ||
166 ($#$action_parts == $#{$best_action->{parts}} &&
167 $#$captures < $#{$best_action->{captures}}))){
169 actions => [ $action, @$actions ],
170 captures=> [ @captures, @$captures ],
171 parts => $action_parts
177 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
178 next TRY_ACTION unless $action->match($c);
180 my $args_attr = $action->attributes->{Args}->[0];
182 # No best action currently
183 # OR This one matches with fewer parts left than the current best action,
184 # And therefore is a better match
185 # OR No parts and this expects 0
186 # The current best action might also be Args(0),
187 # but we couldn't chose between then anyway so we'll take the last seen
190 @parts < @{$best_action->{parts}} ||
191 (!@parts && $args_attr eq 0)){
193 actions => [ $action ],
201 return @$best_action{qw/actions captures parts/} if $best_action;
205 =head2 $self->register( $c, $action )
207 Calls register_path for every Path attribute for the given $action.
212 my ( $self, $c, $action ) = @_;
214 my @chained_attr = @{ $action->attributes->{Chained} || [] };
216 return 0 unless @chained_attr;
218 if (@chained_attr > 1) {
219 Catalyst::Exception->throw(
220 "Multiple Chained attributes not supported registering ${action}"
224 my $children = ($self->{children_of}{ $chained_attr[0] } ||= {});
226 my @path_part = @{ $action->attributes->{PathPart} || [] };
228 my $part = $action->name;
230 if (@path_part == 1 && defined $path_part[0]) {
231 $part = $path_part[0];
232 } elsif (@path_part > 1) {
233 Catalyst::Exception->throw(
234 "Multiple PathPart attributes not supported registering ${action}"
238 if ($part =~ m(^/)) {
239 Catalyst::Exception->throw(
240 "Absolute parameters to PathPart not allowed registering ${action}"
244 $action->attributes->{PartPath} = [ $part ];
246 unshift(@{ $children->{$part} ||= [] }, $action);
248 ($self->{actions} ||= {})->{'/'.$action->reverse} = $action;
250 unless ($action->attributes->{CaptureArgs}) {
251 unshift(@{ $self->{endpoints} ||= [] }, $action);
257 =head2 $self->uri_for_action($action, $captures)
259 Get the URI part for the action, using C<$captures> to fill
265 my ( $self, $action, $captures ) = @_;
267 return undef unless ($action->attributes->{Chained}
268 && !$action->attributes->{CaptureArgs});
271 my @captures = @$captures;
272 my $parent = "DUMMY";
275 if (my $cap = $curr->attributes->{CaptureArgs}) {
276 return undef unless @captures >= $cap->[0]; # not enough captures
278 unshift(@parts, splice(@captures, -$cap->[0]));
281 if (my $pp = $curr->attributes->{PartPath}) {
282 unshift(@parts, $pp->[0])
283 if (defined($pp->[0]) && length($pp->[0]));
285 $parent = $curr->attributes->{Chained}->[0];
286 $curr = $self->{actions}{$parent};
289 return undef unless $parent eq '/'; # fail for dangling action
291 return undef if @captures; # fail for too many captures
293 return join('/', '', @parts);
301 The C<Chained> attribute allows you to chain public path parts together
302 by their private names. A chain part's path can be specified with
303 C<PathPart> and can be declared to expect an arbitrary number of
304 arguments. The endpoint of the chain specifies how many arguments it
305 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
306 C<:Args> without an integer would be unlimited. The path parts that
307 aren't endpoints are using C<CaptureArgs> to specify how many parameters
308 they expect to receive. As an example setup:
310 package MyApp::Controller::Greeting;
311 use base qw/ Catalyst::Controller /;
313 # this is the beginning of our chain
314 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
315 my ( $self, $c, $integer ) = @_;
316 $c->stash->{ message } = "Hello ";
317 $c->stash->{ arg_sum } = $integer;
320 # this is our endpoint, because it has no :CaptureArgs
321 sub world : PathPart('world') Chained('hello') Args(1) {
322 my ( $self, $c, $integer ) = @_;
323 $c->stash->{ message } .= "World!";
324 $c->stash->{ arg_sum } += $integer;
326 $c->response->body( join "<br/>\n" =>
327 $c->stash->{ message }, $c->stash->{ arg_sum } );
330 The debug output provides a separate table for chained actions, showing
331 the whole chain as it would match and the actions it contains. Here's an
332 example of the startup output with our actions above:
335 [debug] Loaded Path Part actions:
336 .-----------------------+------------------------------.
337 | Path Spec | Private |
338 +-----------------------+------------------------------+
339 | /hello/*/world/* | /greeting/hello (1) |
340 | | => /greeting/world |
341 '-----------------------+------------------------------'
344 As you can see, Catalyst only deals with chains as whole paths and
345 builds one for each endpoint, which are the actions with C<:Chained> but
346 without C<:CaptureArgs>.
348 Let's assume this application gets a request at the path
349 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
350 to the C<hello> action and pass the value C<23> as an argument to it
351 after the context. It does so because we have previously used
352 C<:CaptureArgs(1)> to declare that it has one path part after itself as
353 its argument. We told Catalyst that this is the beginning of the chain
354 by specifying C<:Chained('/')>. Also note that instead of saying
355 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
356 defaults to the name of the action.
358 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
359 action. This is the last action to be called: Catalyst knows this is an
360 endpoint because we did not specify a C<:CaptureArgs>
361 attribute. Nevertheless we specify that this action expects an argument,
362 but at this point we're using C<:Args(1)> to do that. We could also have
363 said C<:Args> or left it out altogether, which would mean this action
364 would get all arguments that are there. This action's C<:Chained>
365 attribute says C<hello> and tells Catalyst that the C<hello> action in
366 the current controller is its parent.
368 With this we have built a chain consisting of two public path parts.
369 C<hello> captures one part of the path as its argument, and also
370 specifies the path root as its parent. So this part is
371 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
372 argument. It sums up to the path part C<world/$arg>. This leads to a
373 complete chain of C</hello/$arg/world/$arg> which is matched against the
376 This example application would, if run and called by e.g.
377 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
378 value C<arg_sum> to "23". The C<world> action would then append "World!"
379 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
380 sake of simplicity no view is shown. Instead we just put the values of
381 the stash into our body. So the output would look like:
386 And our test server would have given us this debugging output for the
390 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
391 [debug] Path is "/greeting/world"
392 [debug] Arguments are "12"
393 [info] Request took 0.164113s (6.093/s)
394 .------------------------------------------+-----------.
396 +------------------------------------------+-----------+
397 | /greeting/hello | 0.000029s |
398 | /greeting/world | 0.000024s |
399 '------------------------------------------+-----------'
402 What would be common uses of this dispatch technique? It gives the
403 possibility to split up logic that contains steps that each depend on
404 each other. An example would be, for example, a wiki path like
405 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
408 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
409 my ( $self, $c, $page_name ) = @_;
410 # load the page named $page_name and put the object
414 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
415 my ( $self, $c, $revision_id ) = @_;
416 # use the page object in the stash to get at its
417 # revision with number $revision_id
420 sub view : PathPart Chained('rev') Args(0) {
421 my ( $self, $c ) = @_;
422 # display the revision in our stash. Another option
423 # would be to forward a compatible object to the action
424 # that displays the default wiki pages, unless we want
425 # a different interface here, for example restore
429 It would now be possible to add other endpoints, for example C<restore>
430 to restore this specific revision as the current state.
432 You don't have to put all the chained actions in one controller. The
433 specification of the parent through C<:Chained> also takes an absolute
434 action path as its argument. Just specify it with a leading C</>.
436 If you want, for example, to have actions for the public paths
437 C</foo/12/edit> and C</foo/12>, just specify two actions with
438 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
439 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
440 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
441 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
442 this debugging output:
445 [debug] Loaded Path Part actions:
446 .-----------------------+------------------------------.
447 | Path Spec | Private |
448 +-----------------------+------------------------------+
449 | /foo/* | /controller/foo_view |
450 | /foo/*/edit | /controller/foo_load (1) |
451 | | => /controller/edit |
452 '-----------------------+------------------------------'
455 Here's a more detailed specification of the attributes belonging to
464 Sets the name of this part of the chain. If it is specified without
465 arguments, it takes the name of the action as default. So basically
466 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
467 This can also contain slashes to bind to a deeper level. An action
468 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
469 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
470 effect as using C<:PathPart>, it would default to the action name.
474 Has to be specified for every child in the chain. Possible values are
475 absolute and relative private action paths, with the relatives pointing
476 to the current controller, or a single slash C</> to tell Catalyst that
477 this is the root of a chain. The attribute C<:Chained> without arguments
478 also defaults to the C</> behavior.
480 Because you can specify an absolute path to the parent action, it
481 doesn't matter to Catalyst where that parent is located. So, if your
482 design requests it, you can redispatch a chain through any controller or
485 Another interesting possibility gives C<:Chained('.')>, which chains
486 itself to an action with the path of the current controller's namespace.
489 # in MyApp::Controller::Foo
490 sub bar : Chained CaptureArgs(1) { ... }
492 # in MyApp::Controller::Foo::Bar
493 sub baz : Chained('.') Args(1) { ... }
495 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
496 as the argument to Chained here chains the C<baz> action to an action
497 with the path of the current controller namespace, namely
498 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
499 chain comes out as the end product.
503 Must be specified for every part of the chain that is not an
504 endpoint. With this attribute Catalyst knows how many of the following
505 parts of the path (separated by C</>) this action wants to capture as
506 its arguments. If it doesn't expect any, just specify
507 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
508 after the context, but you can also find them as array references in
509 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
510 level of the action in the chain that captured the parts of the path.
512 An action that is part of a chain (that is, one that has a C<:Chained>
513 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
518 By default, endpoints receive the rest of the arguments in the path. You
519 can tell Catalyst through C<:Args> explicitly how many arguments your
520 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
521 also affects whether this chain is invoked on a request. A chain with an
522 endpoint specifying one argument will only match if exactly one argument
525 You can specify an exact number of arguments like C<:Args(3)>, including
526 C<0>. If you just say C<:Args> without any arguments, it is the same as
527 leaving it out altogether: The chain is matched regardless of the number
528 of path parts after the endpoint.
530 Just as with C<:CaptureArgs>, the arguments get passed to the action in
531 C<@_> after the context object. They can also be reached through
532 C<$c-E<gt>request-E<gt>arguments>.
536 =head2 Auto actions, dispatching and forwarding
538 Note that the list of C<auto> actions called depends on the private path
539 of the endpoint of the chain, not on the chained actions way. The
540 C<auto> actions will be run before the chain dispatching begins. In
541 every other aspect, C<auto> actions behave as documented.
543 The C<forward>ing to other actions does just what you would expect. But if
544 you C<detach> out of a chain, the rest of the chain will not get called
549 Catalyst Contributors, see Catalyst.pm
553 This program is free software, you can redistribute it and/or modify it under
554 the same terms as Perl itself.