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 $parent = '/'.join('/', $action->namespace, $parent);
201 $action->attributes->{Chained} = [ $parent ];
203 my $children = ($self->{children_of}{$parent} ||= {});
205 my @path_part = @{ $action->attributes->{PathPart} || [] };
207 my $part = $action->name;
209 if (@path_part == 1 && defined $path_part[0]) {
210 $part = $path_part[0];
211 } elsif (@path_part > 1) {
212 Catalyst::Exception->throw(
213 "Multiple PathPart attributes not supported registering ${action}"
217 if ($part =~ m(^/)) {
218 Catalyst::Exception->throw(
219 "Absolute parameters to PathPart not allowed registering ${action}"
223 $action->attributes->{PartPath} = [ $part ];
225 unshift(@{ $children->{$part} ||= [] }, $action);
227 ($self->{actions} ||= {})->{'/'.$action->reverse} = $action;
229 unless ($action->attributes->{CaptureArgs}) {
230 unshift(@{ $self->{endpoints} ||= [] }, $action);
236 =head2 $self->uri_for_action($action, $captures)
238 Get the URI part for the action, using C<$captures> to fill
244 my ( $self, $action, $captures ) = @_;
246 return undef unless ($action->attributes->{Chained}
247 && !$action->attributes->{CaptureArgs});
250 my @captures = @$captures;
251 my $parent = "DUMMY";
254 if (my $cap = $curr->attributes->{CaptureArgs}) {
255 return undef unless @captures >= $cap->[0]; # not enough captures
257 unshift(@parts, splice(@captures, -$cap->[0]));
260 if (my $pp = $curr->attributes->{PartPath}) {
261 unshift(@parts, $pp->[0])
262 if (defined($pp->[0]) && length($pp->[0]));
264 $parent = $curr->attributes->{Chained}->[0];
265 $curr = $self->{actions}{$parent};
268 return undef unless $parent eq '/'; # fail for dangling action
270 return undef if @captures; # fail for too many captures
272 return join('/', '', @parts);
280 The C<Chained> attribute allows you to chain public path parts together
281 by their private names. A chain part's path can be specified with
282 C<PathPart> and can be declared to expect an arbitrary number of
283 arguments. The endpoint of the chain specifies how many arguments it
284 gets through the C<Args> attribute. C<:Args(0)> would be none at all,
285 C<:Args> without an integer would be unlimited. The path parts that
286 aren't endpoints are using C<CaptureArgs> to specify how many parameters
287 they expect to receive. As an example setup:
289 package MyApp::Controller::Greeting;
290 use base qw/ Catalyst::Controller /;
292 # this is the beginning of our chain
293 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
294 my ( $self, $c, $integer ) = @_;
295 $c->stash->{ message } = "Hello ";
296 $c->stash->{ arg_sum } = $integer;
299 # this is our endpoint, because it has no :CaptureArgs
300 sub world : PathPart('world') Chained('hello') Args(1) {
301 my ( $self, $c, $integer ) = @_;
302 $c->stash->{ message } .= "World!";
303 $c->stash->{ arg_sum } += $integer;
305 $c->response->body( join "<br/>\n" =>
306 $c->stash->{ message }, $c->stash->{ arg_sum } );
309 The debug output provides a separate table for chained actions, showing
310 the whole chain as it would match and the actions it contains. Here's an
311 example of the startup output with our actions above:
314 [debug] Loaded Path Part actions:
315 .-----------------------+------------------------------.
316 | Path Spec | Private |
317 +-----------------------+------------------------------+
318 | /hello/*/world/* | /greeting/hello (1) |
319 | | => /greeting/world |
320 '-----------------------+------------------------------'
323 As you can see, Catalyst only deals with chains as whole paths and
324 builds one for each endpoint, which are the actions with C<:Chained> but
325 without C<:CaptureArgs>.
327 Let's assume this application gets a request at the path
328 C</hello/23/world/12>. What happens then? First, Catalyst will dispatch
329 to the C<hello> action and pass the value C<23> as an argument to it
330 after the context. It does so because we have previously used
331 C<:CaptureArgs(1)> to declare that it has one path part after itself as
332 its argument. We told Catalyst that this is the beginning of the chain
333 by specifying C<:Chained('/')>. Also note that instead of saying
334 C<:PathPart('hello')> we could also just have said C<:PathPart>, as it
335 defaults to the name of the action.
337 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
338 action. This is the last action to be called: Catalyst knows this is an
339 endpoint because we did not specify a C<:CaptureArgs>
340 attribute. Nevertheless we specify that this action expects an argument,
341 but at this point we're using C<:Args(1)> to do that. We could also have
342 said C<:Args> or left it out altogether, which would mean this action
343 would get all arguments that are there. This action's C<:Chained>
344 attribute says C<hello> and tells Catalyst that the C<hello> action in
345 the current controller is its parent.
347 With this we have built a chain consisting of two public path parts.
348 C<hello> captures one part of the path as its argument, and also
349 specifies the path root as its parent. So this part is
350 C</hello/$arg>. The next part is the endpoint C<world>, expecting one
351 argument. It sums up to the path part C<world/$arg>. This leads to a
352 complete chain of C</hello/$arg/world/$arg> which is matched against the
355 This example application would, if run and called by e.g.
356 C</hello/23/world/12>, set the stash value C<message> to "Hello" and the
357 value C<arg_sum> to "23". The C<world> action would then append "World!"
358 to C<message> and add C<12> to the stash's C<arg_sum> value. For the
359 sake of simplicity no view is shown. Instead we just put the values of
360 the stash into our body. So the output would look like:
365 And our test server would have given us this debugging output for the
369 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
370 [debug] Path is "/greeting/world"
371 [debug] Arguments are "12"
372 [info] Request took 0.164113s (6.093/s)
373 .------------------------------------------+-----------.
375 +------------------------------------------+-----------+
376 | /greeting/hello | 0.000029s |
377 | /greeting/world | 0.000024s |
378 '------------------------------------------+-----------'
381 What would be common uses of this dispatch technique? It gives the
382 possibility to split up logic that contains steps that each depend on
383 each other. An example would be, for example, a wiki path like
384 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
387 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
388 my ( $self, $c, $page_name ) = @_;
389 # load the page named $page_name and put the object
393 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
394 my ( $self, $c, $revision_id ) = @_;
395 # use the page object in the stash to get at its
396 # revision with number $revision_id
399 sub view : PathPart Chained('rev') Args(0) {
400 my ( $self, $c ) = @_;
401 # display the revision in our stash. Another option
402 # would be to forward a compatible object to the action
403 # that displays the default wiki pages, unless we want
404 # a different interface here, for example restore
408 It would now be possible to add other endpoints, for example C<restore>
409 to restore this specific revision as the current state.
411 You don't have to put all the chained actions in one controller. The
412 specification of the parent through C<:Chained> also takes an absolute
413 action path as its argument. Just specify it with a leading C</>.
415 If you want, for example, to have actions for the public paths
416 C</foo/12/edit> and C</foo/12>, just specify two actions with
417 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
418 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
419 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
420 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
421 this debugging output:
424 [debug] Loaded Path Part actions:
425 .-----------------------+------------------------------.
426 | Path Spec | Private |
427 +-----------------------+------------------------------+
428 | /foo/* | /controller/foo_view |
429 | /foo/*/edit | /controller/foo_load (1) |
430 | | => /controller/edit |
431 '-----------------------+------------------------------'
434 Here's a more detailed specification of the attributes belonging to
443 Sets the name of this part of the chain. If it is specified without
444 arguments, it takes the name of the action as default. So basically
445 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
446 This can also contain slashes to bind to a deeper level. An action
447 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
448 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
449 effect as using C<:PathPart>, it would default to the action name.
453 Has to be specified for every child in the chain. Possible values are
454 absolute and relative private action paths, with the relatives pointing
455 to the current controller, or a single slash C</> to tell Catalyst that
456 this is the root of a chain. The attribute C<:Chained> without aguments
457 also defaults to the C</> behavior.
459 Because you can specify an absolute path to the parent action, it
460 doesn't matter to Catalyst where that parent is located. So, if your
461 design requests it, you can redispatch a chain through any controller or
464 Another interesting possibility gives C<:Chained('.')>, which chains
465 itself to an action with the path of the current controller's namespace.
468 # in MyApp::Controller::Foo
469 sub bar : Chained CaptureArgs(1) { ... }
471 # in MyApp::Controller::Foo::Bar
472 sub baz : Chained('.') Args(1) { ... }
474 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
475 as the argument to Chained here chains the C<baz> action to an action
476 with the path of the current controller namespace, namely
477 C</foo/bar>. That action chains directly to C</>, so the C</bar/*/baz/*>
478 chain comes out as the end product.
482 Must be specified for every part of the chain that is not an
483 endpoint. With this attribute Catalyst knows how many of the following
484 parts of the path (separated by C</>) this action wants to capture as
485 its arguments. If it doesn't expect any, just specify
486 C<:CaptureArgs(0)>. The captures get passed to the action's C<@_> right
487 after the context, but you can also find them as array references in
488 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
489 level of the action in the chain that captured the parts of the path.
491 An action that is part of a chain (that is, one that has a C<:Chained>
492 attribute) but has no C<:CaptureArgs> attribute is treated by Catalyst
497 By default, endpoints receive the rest of the arguments in the path. You
498 can tell Catalyst through C<:Args> explicitly how many arguments your
499 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
500 also affects whether this chain is invoked on a request. A chain with an
501 endpoint specifying one argument will only match if exactly one argument
504 You can specify an exact number of arguments like C<:Args(3)>, including
505 C<0>. If you just say C<:Args> without any arguments, it is the same as
506 leaving it out altogether: The chain is matched regardless of the number
507 of path parts after the endpoint.
509 Just as with C<:CaptureArgs>, the arguments get passed to the action in
510 C<@_> after the context object. They can also be reached through
511 C<$c-E<gt>request-E<gt>arguments>.
515 =head2 Auto actions, dispatching and forwarding
517 Note that the list of C<auto> actions called depends on the private path
518 of the endpoint of the chain, not on the chained actions way. The
519 C<auto> actions will be run before the chain dispatching begins. In
520 every other aspect, C<auto> actions behave as documented.
522 The C<forward>ing to other actions does just what you would expect. But if
523 you C<detach> out of a chain, the rest of the chain will not get called
528 Matt S Trout <mst@shadowcatsystems.co.uk>
532 This program is free software, you can redistribute it and/or modify it under
533 the same terms as Perl itself.