1 package Catalyst::DispatchType::Chained;
5 use Catalyst::ActionChain;
8 extends 'Catalyst::DispatchType';
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, $path ) = @_;
122 return 0 if @{$c->req->args};
124 my @parts = split('/', $path);
126 my ($chain, $captures, $parts) = $self->recurse_match($c, '/', \@parts);
127 push @{$c->req->args}, @$parts if $parts && @$parts;
129 return 0 unless $chain;
131 my $action = Catalyst::ActionChain->from_chain($chain);
133 $c->req->action("/${action}");
134 $c->req->match("/${action}");
135 $c->req->captures($captures);
137 $c->namespace( $action->namespace );
142 =head2 $self->recurse_match( $c, $parent, \@path_parts )
144 Recursive search for a matching chain.
149 my ( $self, $c, $parent, $path_parts ) = @_;
150 my $children = $self->_children_of->{$parent};
151 return () unless $children;
154 TRY: foreach my $try_part (sort { length($b) <=> length($a) }
156 # $b then $a to try longest part first
157 my @parts = @$path_parts;
158 if (length $try_part) { # test and strip PathPart
160 ($try_part eq join('/', # assemble equal number of parts
161 splice( # and strip them off @parts as well
162 @parts, 0, scalar(@{[split('/', $try_part)]})
163 ))); # @{[]} to avoid split to @_
165 my @try_actions = @{$children->{$try_part}};
166 TRY_ACTION: foreach my $action (@try_actions) {
167 if (my $capture_attr = $action->attributes->{CaptureArgs}) {
169 # Short-circuit if not enough remaining parts
170 next TRY_ACTION unless @parts >= $capture_attr->[0];
173 my @parts = @parts; # localise
175 # strip CaptureArgs into list
176 push(@captures, splice(@parts, 0, $capture_attr->[0]));
178 # try the remaining parts against children of this action
179 my ($actions, $captures, $action_parts) = $self->recurse_match(
180 $c, '/'.$action->reverse, \@parts
182 if ($actions && (!$best_action || $#$action_parts < $#{$best_action->{parts}})){
184 actions => [ $action, @$actions ],
185 captures=> [ @captures, @$captures ],
186 parts => $action_parts
192 local $c->req->{arguments} = [ @{$c->req->args}, @parts ];
193 next TRY_ACTION unless $action->match($c);
195 my $args_attr = $action->attributes->{Args}->[0];
197 # No best action currently
198 # OR This one matches with fewer parts left than the current best action,
199 # And therefore is a better match
200 # OR No parts and this expects 0
201 # The current best action might also be Args(0),
202 # but we couldn't chose between then anyway so we'll take the last seen
205 @parts < @{$best_action->{parts}} ||
206 (!@parts && $args_attr eq 0)){
208 actions => [ $action ],
216 return @$best_action{qw/actions captures parts/} if $best_action;
220 =head2 $self->register( $c, $action )
222 Calls register_path for every Path attribute for the given $action.
227 my ( $self, $c, $action ) = @_;
229 my @chained_attr = @{ $action->attributes->{Chained} || [] };
231 return 0 unless @chained_attr;
233 if (@chained_attr > 2) {
234 Catalyst::Exception->throw(
235 "Multiple Chained attributes not supported registering ${action}"
239 my $parent = $chained_attr[0];
241 if (defined($parent) && length($parent)) {
242 if ($parent eq '.') {
243 $parent = '/'.$action->namespace;
244 } elsif ($parent !~ m/^\//) {
245 if ($action->namespace) {
246 $parent = '/'.join('/', $action->namespace, $parent);
248 $parent = '/'.$parent; # special case namespace '' (root)
255 $action->attributes->{Chained} = [ $parent ];
257 my $children = $self->_children_of->{$parent};
259 my @path_part = @{ $action->attributes->{PathPart} || [] };
261 my $part = $action->name;
263 if (@path_part == 1 && defined $path_part[0]) {
264 $part = $path_part[0];
265 } elsif (@path_part > 1) {
266 Catalyst::Exception->throw(
267 "Multiple PathPart attributes not supported registering ${action}"
271 if ($part =~ m(^/)) {
272 Catalyst::Exception->throw(
273 "Absolute parameters to PathPart not allowed registering ${action}"
277 $action->attributes->{PartPath} = [ $part ];
279 unshift(@{ $children->{$part} ||= [] }, $action);
281 $self->_actions->{'/'.$action->reverse} = $action;
283 unless ($action->attributes->{CaptureArgs}) {
284 unshift(@{ $self->_endpoints }, $action);
290 =head2 $self->uri_for_action($action, $captures)
292 Get the URI part for the action, using C<$captures> to fill
298 my ( $self, $action, $captures ) = @_;
300 return undef unless ($action->attributes->{Chained}
301 && !$action->attributes->{CaptureArgs});
304 my @captures = @$captures;
305 my $parent = "DUMMY";
308 if (my $cap = $curr->attributes->{CaptureArgs}) {
309 return undef unless @captures >= $cap->[0]; # not enough captures
311 unshift(@parts, splice(@captures, -$cap->[0]));
314 if (my $pp = $curr->attributes->{PartPath}) {
315 unshift(@parts, $pp->[0])
316 if (defined($pp->[0]) && length($pp->[0]));
318 $parent = $curr->attributes->{Chained}->[0];
319 $curr = $self->_actions->{$parent};
322 return undef unless $parent eq '/'; # fail for dangling action
324 return undef if @captures; # fail for too many captures
326 return join('/', '', @parts);
334 The C<Chained> attribute allows you to chain public path parts together
335 by their private names. A chain part's path can be specified with
336 C<PathPart> and can be declared to expect an arbitrary number of
337 arguments. The endpoint of the chain specifies how many arguments it
338 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
339 C<:Args> without an integer would be unlimited. The path parts that
340 aren't endpoints are using C<CaptureArgs> to specify how many parameters
341 they expect to receive. As an example setup:
343 package MyApp::Controller::Greeting;
344 use base qw/ Catalyst::Controller /;
346 # this is the beginning of our chain
347 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
348 my ( $self, $c, $integer ) = @_;
349 $c->stash->{ message } = "Hello ";
350 $c->stash->{ arg_sum } = $integer;
353 # this is our endpoint, because it has no :CaptureArgs
354 sub world : PathPart('world') Chained('hello') Args(1) {
355 my ( $self, $c, $integer ) = @_;
356 $c->stash->{ message } .= "World!";
357 $c->stash->{ arg_sum } += $integer;
359 $c->response->body( join "<br/>\n" =>
360 $c->stash->{ message }, $c->stash->{ arg_sum } );
363 The debug output provides a separate table for chained actions, showing
364 the whole chain as it would match and the actions it contains. Here's an
365 example of the startup output with our actions above:
368 [debug] Loaded Path Part actions:
369 .-----------------------+------------------------------.
370 | Path Spec | Private |
371 +-----------------------+------------------------------+
372 | /hello/*/world/* | /greeting/hello (1) |
373 | | => /greeting/world |
374 '-----------------------+------------------------------'
377 As you can see, Catalyst only deals with chains as whole paths and
378 builds one for each endpoint, which are the actions with C<:Chained> but
379 without C<:CaptureArgs>.
381 Let's assume this application gets a request at the path
382 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
383 to the C<hello> action and pass the value C<23> as an argument to it
384 after the context. It does so because we have previously used
385 C<:CaptureArgs(1)> to declare that it has one path part after itself as
386 its argument. We told Catalyst that this is the beginning of the chain
387 by specifying C<:Chained('/')>. Also note that instead of saying
388 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
389 defaults to the name of the action.
391 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
392 action. This is the last action to be called: Catalyst knows this is an
393 endpoint because we did not specify a C<:CaptureArgs>
394 attribute. Nevertheless we specify that this action expects an argument,
395 but at this point we're using C<:Args(1)> to do that. We could also have
396 said C<:Args> or left it out altogether, which would mean this action
397 would get all arguments that are there. This action's C<:Chained>
398 attribute says C<hello> and tells Catalyst that the C<hello> action in
399 the current controller is its parent.
401 With this we have built a chain consisting of two public path parts.
402 C<hello> captures one part of the path as its argument, and also
403 specifies the path root as its parent. So this part is
404 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
405 argument. It sums up to the path part C<world/$arg>. This leads to a
406 complete chain of C</hello/$arg/world/$arg> which is matched against the
409 This example application would, if run and called by e.g.
410 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
411 value C<arg_sum> to "23". The C<world> action would then append "World!"
412 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
413 sake of simplicity no view is shown. Instead we just put the values of
414 the stash into our body. So the output would look like:
419 And our test server would have given us this debugging output for the
423 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
424 [debug] Path is "/greeting/world"
425 [debug] Arguments are "12"
426 [info] Request took 0.164113s (6.093/s)
427 .------------------------------------------+-----------.
429 +------------------------------------------+-----------+
430 | /greeting/hello | 0.000029s |
431 | /greeting/world | 0.000024s |
432 '------------------------------------------+-----------'
435 What would be common uses of this dispatch technique? It gives the
436 possibility to split up logic that contains steps that each depend on
437 each other. An example would be, for example, a wiki path like
438 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
441 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
442 my ( $self, $c, $page_name ) = @_;
443 # load the page named $page_name and put the object
447 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
448 my ( $self, $c, $revision_id ) = @_;
449 # use the page object in the stash to get at its
450 # revision with number $revision_id
453 sub view : PathPart Chained('rev') Args(0) {
454 my ( $self, $c ) = @_;
455 # display the revision in our stash. Another option
456 # would be to forward a compatible object to the action
457 # that displays the default wiki pages, unless we want
458 # a different interface here, for example restore
462 It would now be possible to add other endpoints, for example C<restore>
463 to restore this specific revision as the current state.
465 You don't have to put all the chained actions in one controller. The
466 specification of the parent through C<:Chained> also takes an absolute
467 action path as its argument. Just specify it with a leading C</>.
469 If you want, for example, to have actions for the public paths
470 C</foo/12/edit> and C</foo/12>, just specify two actions with
471 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
472 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
473 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
474 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
475 this debugging output:
478 [debug] Loaded Path Part actions:
479 .-----------------------+------------------------------.
480 | Path Spec | Private |
481 +-----------------------+------------------------------+
482 | /foo/* | /controller/foo_view |
483 | /foo/*/edit | /controller/foo_load (1) |
484 | | => /controller/edit |
485 '-----------------------+------------------------------'
488 Here's a more detailed specification of the attributes belonging to
497 Sets the name of this part of the chain. If it is specified without
498 arguments, it takes the name of the action as default. So basically
499 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
500 This can also contain slashes to bind to a deeper level. An action
501 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
502 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
503 effect as using C<:PathPart>, it would default to the action name.
507 Has to be specified for every child in the chain. Possible values are
508 absolute and relative private action paths, with the relatives pointing
509 to the current controller, or a single slash C</> to tell Catalyst that
510 this is the root of a chain. The attribute C<:Chained> without arguments
511 also defaults to the C</> behavior.
513 Because you can specify an absolute path to the parent action, it
514 doesn't matter to Catalyst where that parent is located. So, if your
515 design requests it, you can redispatch a chain through any controller or
518 Another interesting possibility gives C<:Chained('.')>, which chains
519 itself to an action with the path of the current controller's namespace.
522 # in MyApp::Controller::Foo
523 sub bar : Chained CaptureArgs(1) { ... }
525 # in MyApp::Controller::Foo::Bar
526 sub baz : Chained('.') Args(1) { ... }
528 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
529 as the argument to Chained here chains the C<baz> action to an action
530 with the path of the current controller namespace, namely
531 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
532 chain comes out as the end product.
536 Must be specified for every part of the chain that is not an
537 endpoint. With this attribute Catalyst knows how many of the following
538 parts of the path (separated by C</>) this action wants to capture as
539 its arguments. If it doesn't expect any, just specify
540 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
541 after the context, but you can also find them as array references in
542 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
543 level of the action in the chain that captured the parts of the path.
545 An action that is part of a chain (that is, one that has a C<:Chained>
546 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
551 By default, endpoints receive the rest of the arguments in the path. You
552 can tell Catalyst through C<:Args> explicitly how many arguments your
553 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
554 also affects whether this chain is invoked on a request. A chain with an
555 endpoint specifying one argument will only match if exactly one argument
558 You can specify an exact number of arguments like C<:Args(3)>, including
559 C<0>. If you just say C<:Args> without any arguments, it is the same as
560 leaving it out altogether: The chain is matched regardless of the number
561 of path parts after the endpoint.
563 Just as with C<:CaptureArgs>, the arguments get passed to the action in
564 C<@_> after the context object. They can also be reached through
565 C<$c-E<gt>request-E<gt>arguments>.
569 =head2 Auto actions, dispatching and forwarding
571 Note that the list of C<auto> actions called depends on the private path
572 of the endpoint of the chain, not on the chained actions way. The
573 C<auto> actions will be run before the chain dispatching begins. In
574 every other aspect, C<auto> actions behave as documented.
576 The C<forward>ing to other actions does just what you would expect. But if
577 you C<detach> out of a chain, the rest of the chain will not get called
582 Matt S Trout <mst@shadowcatsystems.co.uk>
586 This program is free software, you can redistribute it and/or modify it under
587 the same terms as Perl itself.