1 package Catalyst::DispatchType::Chained;
4 extends 'Catalyst::DispatchType';
7 use Catalyst::ActionChain;
31 # please don't perltidy this. hairy code within.
35 Catalyst::DispatchType::Chained - Path Part DispatchType
39 # root action - captures one argument after it
40 sub foo_setup : Chained('/') PathPart('foo') CaptureArgs(1) {
41 my ( $self, $c, $foo_arg ) = @_;
45 # child action endpoint - takes one argument
46 sub bar : Chained('foo_setup') Args(1) {
47 my ( $self, $c, $bar_arg ) = @_;
57 =head2 $self->list($c)
59 Debug output for Path Part dispatch points
64 my ( $self, $c ) = @_;
66 return unless $self->_endpoints;
68 my $paths = Text::SimpleTable->new(
69 [ 35, 'Path Spec' ], [ 36, 'Private' ]
72 ENDPOINT: foreach my $endpoint (
73 sort { $a->reverse cmp $b->reverse }
74 @{ $self->_endpoints }
76 my $args = $endpoint->attributes->{Args}->[0];
77 my @parts = (defined($args) ? (("*") x $args) : '...');
82 if (my $cap = $curr->attributes->{CaptureArgs}) {
83 unshift(@parts, (("*") x $cap->[0]));
85 if (my $pp = $curr->attributes->{PartPath}) {
86 unshift(@parts, $pp->[0])
87 if (defined $pp->[0] && length $pp->[0]);
89 $parent = $curr->attributes->{Chained}->[0];
90 $curr = $self->_actions->{$parent};
91 unshift(@parents, $curr) if $curr;
93 next ENDPOINT unless $parent eq '/'; # skip dangling action
95 foreach my $p (@parents) {
97 if (my $cap = $p->attributes->{CaptureArgs}) {
98 $name .= ' ('.$cap->[0].')';
100 unless ($p eq $parents[0]) {
101 $name = "-> ${name}";
103 push(@rows, [ '', $name ]);
105 push(@rows, [ '', (@rows ? "=> " : '')."/${endpoint}" ]);
106 $rows[0][0] = join('/', '', @parts);
107 $paths->row(@$_) for @rows;
110 $c->log->debug( "Loaded Chained actions:\n" . $paths->draw . "\n" );
113 =head2 $self->match( $c, $path )
115 Calls C<recurse_match> to see if a chain matches the C<$path>.
120 my ( $self, $c, $path ) = @_;
122 my $request = $c->request;
123 return 0 if @{$request->args};
125 my @parts = split('/', $path);
127 my ($chain, $captures, $parts) = $self->recurse_match($c, '/', \@parts);
128 push @{$request->args}, @$parts if $parts && @$parts;
130 return 0 unless $chain;
132 my $action = Catalyst::ActionChain->from_chain($chain);
134 $request->action("/${action}");
135 $request->match("/${action}");
136 $request->captures($captures);
138 $c->namespace( $action->namespace );
143 =head2 $self->recurse_match( $c, $parent, \@path_parts )
145 Recursive search for a matching chain.
150 my ( $self, $c, $parent, $path_parts ) = @_;
151 my $children = $self->_children_of->{$parent};
152 return () unless $children;
155 TRY: foreach my $try_part (sort { length($b) <=> length($a) }
157 # $b then $a to try longest part first
158 my @parts = @$path_parts;
159 if (length $try_part) { # test and strip PathPart
161 ($try_part eq join('/', # assemble equal number of parts
162 splice( # and strip them off @parts as well
163 @parts, 0, scalar(@{[split('/', $try_part)]})
164 ))); # @{[]} to avoid split to @_
166 my @try_actions = @{$children->{$try_part}};
167 TRY_ACTION: foreach my $action (@try_actions) {
168 if (my $capture_attr = $action->attributes->{CaptureArgs}) {
170 # Short-circuit if not enough remaining parts
171 next TRY_ACTION unless @parts >= $capture_attr->[0];
174 my @parts = @parts; # localise
176 # strip CaptureArgs into list
177 push(@captures, splice(@parts, 0, $capture_attr->[0]));
179 # try the remaining parts against children of this action
180 my ($actions, $captures, $action_parts) = $self->recurse_match(
181 $c, '/'.$action->reverse, \@parts
183 if ($actions && (!$best_action || $#$action_parts < $#{$best_action->{parts}})){
185 actions => [ $action, @$actions ],
186 captures=> [ @captures, @$captures ],
187 parts => $action_parts
193 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
194 next TRY_ACTION unless $action->match($c);
196 my $args_attr = $action->attributes->{Args}->[0];
198 # No best action currently
199 # OR This one matches with fewer parts left than the current best action,
200 # And therefore is a better match
201 # OR No parts and this expects 0
202 # The current best action might also be Args(0),
203 # but we couldn't chose between then anyway so we'll take the last seen
206 @parts < @{$best_action->{parts}} ||
207 (!@parts && $args_attr eq 0)){
209 actions => [ $action ],
217 return @$best_action{qw/actions captures parts/} if $best_action;
221 =head2 $self->register( $c, $action )
223 Calls register_path for every Path attribute for the given $action.
228 my ( $self, $c, $action ) = @_;
230 my @chained_attr = @{ $action->attributes->{Chained} || [] };
232 return 0 unless @chained_attr;
234 if (@chained_attr > 2) {
235 Catalyst::Exception->throw(
236 "Multiple Chained attributes not supported registering ${action}"
240 my $parent = $chained_attr[0];
242 if (defined($parent) && length($parent)) {
243 if ($parent eq '.') {
244 $parent = '/'.$action->namespace;
245 } elsif ($parent !~ m/^\//) {
246 if ($action->namespace) {
247 $parent = '/'.join('/', $action->namespace, $parent);
249 $parent = '/'.$parent; # special case namespace '' (root)
256 $action->attributes->{Chained} = [ $parent ];
258 my $children = ($self->_children_of->{$parent} ||= {});
260 my @path_part = @{ $action->attributes->{PathPart} || [] };
262 my $part = $action->name;
264 if (@path_part == 1 && defined $path_part[0]) {
265 $part = $path_part[0];
266 } elsif (@path_part > 1) {
267 Catalyst::Exception->throw(
268 "Multiple PathPart attributes not supported registering ${action}"
272 if ($part =~ m(^/)) {
273 Catalyst::Exception->throw(
274 "Absolute parameters to PathPart not allowed registering ${action}"
278 $action->attributes->{PartPath} = [ $part ];
280 unshift(@{ $children->{$part} ||= [] }, $action);
282 $self->_actions->{'/'.$action->reverse} = $action;
284 unless ($action->attributes->{CaptureArgs}) {
285 unshift(@{ $self->_endpoints }, $action);
291 =head2 $self->uri_for_action($action, $captures)
293 Get the URI part for the action, using C<$captures> to fill
299 my ( $self, $action, $captures ) = @_;
301 return undef unless ($action->attributes->{Chained}
302 && !$action->attributes->{CaptureArgs});
305 my @captures = @$captures;
306 my $parent = "DUMMY";
309 if (my $cap = $curr->attributes->{CaptureArgs}) {
310 return undef unless @captures >= $cap->[0]; # not enough captures
312 unshift(@parts, splice(@captures, -$cap->[0]));
315 if (my $pp = $curr->attributes->{PartPath}) {
316 unshift(@parts, $pp->[0])
317 if (defined($pp->[0]) && length($pp->[0]));
319 $parent = $curr->attributes->{Chained}->[0];
320 $curr = $self->_actions->{$parent};
323 return undef unless $parent eq '/'; # fail for dangling action
325 return undef if @captures; # fail for too many captures
327 return join('/', '', @parts);
332 __PACKAGE__->meta->make_immutable;
338 The C<Chained> attribute allows you to chain public path parts together
339 by their private names. A chain part's path can be specified with
340 C<PathPart> and can be declared to expect an arbitrary number of
341 arguments. The endpoint of the chain specifies how many arguments it
342 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
343 C<:Args> without an integer would be unlimited. The path parts that
344 aren't endpoints are using C<CaptureArgs> to specify how many parameters
345 they expect to receive. As an example setup:
347 package MyApp::Controller::Greeting;
348 use base qw/ Catalyst::Controller /;
350 # this is the beginning of our chain
351 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
352 my ( $self, $c, $integer ) = @_;
353 $c->stash->{ message } = "Hello ";
354 $c->stash->{ arg_sum } = $integer;
357 # this is our endpoint, because it has no :CaptureArgs
358 sub world : PathPart('world') Chained('hello') Args(1) {
359 my ( $self, $c, $integer ) = @_;
360 $c->stash->{ message } .= "World!";
361 $c->stash->{ arg_sum } += $integer;
363 $c->response->body( join "<br/>\n" =>
364 $c->stash->{ message }, $c->stash->{ arg_sum } );
367 The debug output provides a separate table for chained actions, showing
368 the whole chain as it would match and the actions it contains. Here's an
369 example of the startup output with our actions above:
372 [debug] Loaded Path Part actions:
373 .-----------------------+------------------------------.
374 | Path Spec | Private |
375 +-----------------------+------------------------------+
376 | /hello/*/world/* | /greeting/hello (1) |
377 | | => /greeting/world |
378 '-----------------------+------------------------------'
381 As you can see, Catalyst only deals with chains as whole paths and
382 builds one for each endpoint, which are the actions with C<:Chained> but
383 without C<:CaptureArgs>.
385 Let's assume this application gets a request at the path
386 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
387 to the C<hello> action and pass the value C<23> as an argument to it
388 after the context. It does so because we have previously used
389 C<:CaptureArgs(1)> to declare that it has one path part after itself as
390 its argument. We told Catalyst that this is the beginning of the chain
391 by specifying C<:Chained('/')>. Also note that instead of saying
392 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
393 defaults to the name of the action.
395 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
396 action. This is the last action to be called: Catalyst knows this is an
397 endpoint because we did not specify a C<:CaptureArgs>
398 attribute. Nevertheless we specify that this action expects an argument,
399 but at this point we're using C<:Args(1)> to do that. We could also have
400 said C<:Args> or left it out altogether, which would mean this action
401 would get all arguments that are there. This action's C<:Chained>
402 attribute says C<hello> and tells Catalyst that the C<hello> action in
403 the current controller is its parent.
405 With this we have built a chain consisting of two public path parts.
406 C<hello> captures one part of the path as its argument, and also
407 specifies the path root as its parent. So this part is
408 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
409 argument. It sums up to the path part C<world/$arg>. This leads to a
410 complete chain of C</hello/$arg/world/$arg> which is matched against the
413 This example application would, if run and called by e.g.
414 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
415 value C<arg_sum> to "23". The C<world> action would then append "World!"
416 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
417 sake of simplicity no view is shown. Instead we just put the values of
418 the stash into our body. So the output would look like:
423 And our test server would have given us this debugging output for the
427 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
428 [debug] Path is "/greeting/world"
429 [debug] Arguments are "12"
430 [info] Request took 0.164113s (6.093/s)
431 .------------------------------------------+-----------.
433 +------------------------------------------+-----------+
434 | /greeting/hello | 0.000029s |
435 | /greeting/world | 0.000024s |
436 '------------------------------------------+-----------'
439 What would be common uses of this dispatch technique? It gives the
440 possibility to split up logic that contains steps that each depend on
441 each other. An example would be, for example, a wiki path like
442 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
445 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
446 my ( $self, $c, $page_name ) = @_;
447 # load the page named $page_name and put the object
451 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
452 my ( $self, $c, $revision_id ) = @_;
453 # use the page object in the stash to get at its
454 # revision with number $revision_id
457 sub view : PathPart Chained('rev') Args(0) {
458 my ( $self, $c ) = @_;
459 # display the revision in our stash. Another option
460 # would be to forward a compatible object to the action
461 # that displays the default wiki pages, unless we want
462 # a different interface here, for example restore
466 It would now be possible to add other endpoints, for example C<restore>
467 to restore this specific revision as the current state.
469 You don't have to put all the chained actions in one controller. The
470 specification of the parent through C<:Chained> also takes an absolute
471 action path as its argument. Just specify it with a leading C</>.
473 If you want, for example, to have actions for the public paths
474 C</foo/12/edit> and C</foo/12>, just specify two actions with
475 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
476 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
477 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
478 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
479 this debugging output:
482 [debug] Loaded Path Part actions:
483 .-----------------------+------------------------------.
484 | Path Spec | Private |
485 +-----------------------+------------------------------+
486 | /foo/* | /controller/foo_view |
487 | /foo/*/edit | /controller/foo_load (1) |
488 | | => /controller/edit |
489 '-----------------------+------------------------------'
492 Here's a more detailed specification of the attributes belonging to
501 Sets the name of this part of the chain. If it is specified without
502 arguments, it takes the name of the action as default. So basically
503 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
504 This can also contain slashes to bind to a deeper level. An action
505 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
506 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
507 effect as using C<:PathPart>, it would default to the action name.
511 Has to be specified for every child in the chain. Possible values are
512 absolute and relative private action paths, with the relatives pointing
513 to the current controller, or a single slash C</> to tell Catalyst that
514 this is the root of a chain. The attribute C<:Chained> without arguments
515 also defaults to the C</> behavior.
517 Because you can specify an absolute path to the parent action, it
518 doesn't matter to Catalyst where that parent is located. So, if your
519 design requests it, you can redispatch a chain through any controller or
522 Another interesting possibility gives C<:Chained('.')>, which chains
523 itself to an action with the path of the current controller's namespace.
526 # in MyApp::Controller::Foo
527 sub bar : Chained CaptureArgs(1) { ... }
529 # in MyApp::Controller::Foo::Bar
530 sub baz : Chained('.') Args(1) { ... }
532 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
533 as the argument to Chained here chains the C<baz> action to an action
534 with the path of the current controller namespace, namely
535 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
536 chain comes out as the end product.
540 Must be specified for every part of the chain that is not an
541 endpoint. With this attribute Catalyst knows how many of the following
542 parts of the path (separated by C</>) this action wants to capture as
543 its arguments. If it doesn't expect any, just specify
544 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
545 after the context, but you can also find them as array references in
546 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
547 level of the action in the chain that captured the parts of the path.
549 An action that is part of a chain (that is, one that has a C<:Chained>
550 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
555 By default, endpoints receive the rest of the arguments in the path. You
556 can tell Catalyst through C<:Args> explicitly how many arguments your
557 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
558 also affects whether this chain is invoked on a request. A chain with an
559 endpoint specifying one argument will only match if exactly one argument
562 You can specify an exact number of arguments like C<:Args(3)>, including
563 C<0>. If you just say C<:Args> without any arguments, it is the same as
564 leaving it out altogether: The chain is matched regardless of the number
565 of path parts after the endpoint.
567 Just as with C<:CaptureArgs>, the arguments get passed to the action in
568 C<@_> after the context object. They can also be reached through
569 C<$c-E<gt>request-E<gt>arguments>.
573 =head2 Auto actions, dispatching and forwarding
575 Note that the list of C<auto> actions called depends on the private path
576 of the endpoint of the chain, not on the chained actions way. The
577 C<auto> actions will be run before the chain dispatching begins. In
578 every other aspect, C<auto> actions behave as documented.
580 The C<forward>ing to other actions does just what you would expect. But if
581 you C<detach> out of a chain, the rest of the chain will not get called
586 Matt S Trout <mst@shadowcatsystems.co.uk>
590 This program is free software, you can redistribute it and/or modify it under
591 the same terms as Perl itself.