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);
331 __PACKAGE__->meta->make_immutable;
337 The C<Chained> attribute allows you to chain public path parts together
338 by their private names. A chain part's path can be specified with
339 C<PathPart> and can be declared to expect an arbitrary number of
340 arguments. The endpoint of the chain specifies how many arguments it
341 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
342 C<:Args> without an integer would be unlimited. The path parts that
343 aren't endpoints are using C<CaptureArgs> to specify how many parameters
344 they expect to receive. As an example setup:
346 package MyApp::Controller::Greeting;
347 use base qw/ Catalyst::Controller /;
349 # this is the beginning of our chain
350 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
351 my ( $self, $c, $integer ) = @_;
352 $c->stash->{ message } = "Hello ";
353 $c->stash->{ arg_sum } = $integer;
356 # this is our endpoint, because it has no :CaptureArgs
357 sub world : PathPart('world') Chained('hello') Args(1) {
358 my ( $self, $c, $integer ) = @_;
359 $c->stash->{ message } .= "World!";
360 $c->stash->{ arg_sum } += $integer;
362 $c->response->body( join "<br/>\n" =>
363 $c->stash->{ message }, $c->stash->{ arg_sum } );
366 The debug output provides a separate table for chained actions, showing
367 the whole chain as it would match and the actions it contains. Here's an
368 example of the startup output with our actions above:
371 [debug] Loaded Path Part actions:
372 .-----------------------+------------------------------.
373 | Path Spec | Private |
374 +-----------------------+------------------------------+
375 | /hello/*/world/* | /greeting/hello (1) |
376 | | => /greeting/world |
377 '-----------------------+------------------------------'
380 As you can see, Catalyst only deals with chains as whole paths and
381 builds one for each endpoint, which are the actions with C<:Chained> but
382 without C<:CaptureArgs>.
384 Let's assume this application gets a request at the path
385 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
386 to the C<hello> action and pass the value C<23> as an argument to it
387 after the context. It does so because we have previously used
388 C<:CaptureArgs(1)> to declare that it has one path part after itself as
389 its argument. We told Catalyst that this is the beginning of the chain
390 by specifying C<:Chained('/')>. Also note that instead of saying
391 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
392 defaults to the name of the action.
394 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
395 action. This is the last action to be called: Catalyst knows this is an
396 endpoint because we did not specify a C<:CaptureArgs>
397 attribute. Nevertheless we specify that this action expects an argument,
398 but at this point we're using C<:Args(1)> to do that. We could also have
399 said C<:Args> or left it out altogether, which would mean this action
400 would get all arguments that are there. This action's C<:Chained>
401 attribute says C<hello> and tells Catalyst that the C<hello> action in
402 the current controller is its parent.
404 With this we have built a chain consisting of two public path parts.
405 C<hello> captures one part of the path as its argument, and also
406 specifies the path root as its parent. So this part is
407 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
408 argument. It sums up to the path part C<world/$arg>. This leads to a
409 complete chain of C</hello/$arg/world/$arg> which is matched against the
412 This example application would, if run and called by e.g.
413 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
414 value C<arg_sum> to "23". The C<world> action would then append "World!"
415 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
416 sake of simplicity no view is shown. Instead we just put the values of
417 the stash into our body. So the output would look like:
422 And our test server would have given us this debugging output for the
426 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
427 [debug] Path is "/greeting/world"
428 [debug] Arguments are "12"
429 [info] Request took 0.164113s (6.093/s)
430 .------------------------------------------+-----------.
432 +------------------------------------------+-----------+
433 | /greeting/hello | 0.000029s |
434 | /greeting/world | 0.000024s |
435 '------------------------------------------+-----------'
438 What would be common uses of this dispatch technique? It gives the
439 possibility to split up logic that contains steps that each depend on
440 each other. An example would be, for example, a wiki path like
441 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
444 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
445 my ( $self, $c, $page_name ) = @_;
446 # load the page named $page_name and put the object
450 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
451 my ( $self, $c, $revision_id ) = @_;
452 # use the page object in the stash to get at its
453 # revision with number $revision_id
456 sub view : PathPart Chained('rev') Args(0) {
457 my ( $self, $c ) = @_;
458 # display the revision in our stash. Another option
459 # would be to forward a compatible object to the action
460 # that displays the default wiki pages, unless we want
461 # a different interface here, for example restore
465 It would now be possible to add other endpoints, for example C<restore>
466 to restore this specific revision as the current state.
468 You don't have to put all the chained actions in one controller. The
469 specification of the parent through C<:Chained> also takes an absolute
470 action path as its argument. Just specify it with a leading C</>.
472 If you want, for example, to have actions for the public paths
473 C</foo/12/edit> and C</foo/12>, just specify two actions with
474 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
475 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
476 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
477 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
478 this debugging output:
481 [debug] Loaded Path Part actions:
482 .-----------------------+------------------------------.
483 | Path Spec | Private |
484 +-----------------------+------------------------------+
485 | /foo/* | /controller/foo_view |
486 | /foo/*/edit | /controller/foo_load (1) |
487 | | => /controller/edit |
488 '-----------------------+------------------------------'
491 Here's a more detailed specification of the attributes belonging to
500 Sets the name of this part of the chain. If it is specified without
501 arguments, it takes the name of the action as default. So basically
502 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
503 This can also contain slashes to bind to a deeper level. An action
504 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
505 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
506 effect as using C<:PathPart>, it would default to the action name.
510 Has to be specified for every child in the chain. Possible values are
511 absolute and relative private action paths, with the relatives pointing
512 to the current controller, or a single slash C</> to tell Catalyst that
513 this is the root of a chain. The attribute C<:Chained> without arguments
514 also defaults to the C</> behavior.
516 Because you can specify an absolute path to the parent action, it
517 doesn't matter to Catalyst where that parent is located. So, if your
518 design requests it, you can redispatch a chain through any controller or
521 Another interesting possibility gives C<:Chained('.')>, which chains
522 itself to an action with the path of the current controller's namespace.
525 # in MyApp::Controller::Foo
526 sub bar : Chained CaptureArgs(1) { ... }
528 # in MyApp::Controller::Foo::Bar
529 sub baz : Chained('.') Args(1) { ... }
531 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
532 as the argument to Chained here chains the C<baz> action to an action
533 with the path of the current controller namespace, namely
534 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
535 chain comes out as the end product.
539 Must be specified for every part of the chain that is not an
540 endpoint. With this attribute Catalyst knows how many of the following
541 parts of the path (separated by C</>) this action wants to capture as
542 its arguments. If it doesn't expect any, just specify
543 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
544 after the context, but you can also find them as array references in
545 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
546 level of the action in the chain that captured the parts of the path.
548 An action that is part of a chain (that is, one that has a C<:Chained>
549 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
554 By default, endpoints receive the rest of the arguments in the path. You
555 can tell Catalyst through C<:Args> explicitly how many arguments your
556 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
557 also affects whether this chain is invoked on a request. A chain with an
558 endpoint specifying one argument will only match if exactly one argument
561 You can specify an exact number of arguments like C<:Args(3)>, including
562 C<0>. If you just say C<:Args> without any arguments, it is the same as
563 leaving it out altogether: The chain is matched regardless of the number
564 of path parts after the endpoint.
566 Just as with C<:CaptureArgs>, the arguments get passed to the action in
567 C<@_> after the context object. They can also be reached through
568 C<$c-E<gt>request-E<gt>arguments>.
572 =head2 Auto actions, dispatching and forwarding
574 Note that the list of C<auto> actions called depends on the private path
575 of the endpoint of the chain, not on the chained actions way. The
576 C<auto> actions will be run before the chain dispatching begins. In
577 every other aspect, C<auto> actions behave as documented.
579 The C<forward>ing to other actions does just what you would expect. But if
580 you C<detach> out of a chain, the rest of the chain will not get called
585 Matt S Trout <mst@shadowcatsystems.co.uk>
589 This program is free software, you can redistribute it and/or modify it under
590 the same terms as Perl itself.