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 && $action->attributes->{Args});
250 my @captures = @$captures;
251 my $parent = "DUMMY";
254 if (my $cap = $curr->attributes->{CaptureArgs}) {
255 return undef unless @captures >= $cap->[0]; # not enough captures
256 unshift(@parts, splice(@captures, -$cap->[0]));
258 if (my $pp = $curr->attributes->{PartPath}) {
259 unshift(@parts, $pp->[0])
260 if (defined $pp->[0] && length $pp->[0]);
262 $parent = $curr->attributes->{Chained}->[0];
263 $curr = $self->{actions}{$parent};
266 return undef unless $parent eq '/'; # fail for dangling action
268 return undef if @captures; # fail for too many captures
270 return join('/', '', @parts);
278 The C<Chained> attribute allows you to chain public path parts together
279 by their private names. A chain part's path can be specified with C<PathPart>
280 and can be declared to expect an arbitrary number of arguments. The endpoint
281 of the chain specifies how many arguments it gets through the C<Args>
282 attribute. C<:Args(0)> would be none at all, C<:Args> without an integer
283 would be unlimited. The path parts that aren't endpoints are using
284 C<CaptureArgs> to specify how many parameters they expect to receive. As an
287 package MyApp::Controller::Greeting;
288 use base qw/ Catalyst::Controller /;
290 # this is the beginning of our chain
291 sub hello : PathPart('hello') Chained('/') CaptureArgs(1) {
292 my ( $self, $c, $integer ) = @_;
293 $c->stash->{ message } = "Hello ";
294 $c->stash->{ arg_sum } = $integer;
297 # this is our endpoint, because it has no :CaptureArgs
298 sub world : PathPart('world') Chained('hello') Args(1) {
299 my ( $self, $c, $integer ) = @_;
300 $c->stash->{ message } .= "World!";
301 $c->stash->{ arg_sum } += $integer;
303 $c->response->body( join "<br/>\n" =>
304 $c->stash->{ message }, $c->stash->{ arg_sum } );
307 The debug output provides a separate table for chained actions, showing
308 the whole chain as it would match and the actions it contains. Here's
309 an example of the startup output with our actions above:
312 [debug] Loaded Path Part actions:
313 .-----------------------+------------------------------.
314 | Path Spec | Private |
315 +-----------------------+------------------------------+
316 | /hello/*/world/* | /greeting/hello (1) |
317 | | => /greeting/world |
318 '-----------------------+------------------------------'
321 As you can see, Catalyst only deals with chains as whole path and
322 builds one for each endpoint, which are the actions with C<:Chained>
323 but without C<:CaptureArgs>.
325 Let's assume this application gets a request at the path
326 C</hello/23/world/12>, what happens then? First, Catalyst will dispatch
327 to the C<hello> action and pass the value C<23> as argument to it after
328 the context. It does so because we have previously used C<:CaptureArgs(1)>
329 to declare that it has one path part after itself as it's argument. We
330 told Catalyst that this is the beginning of the chain by specifying
331 C<:Chained('/')>. Also note that instead of saying C<:PathPart('hello')>
332 we could also just have said C<:PathPart>, as it defaults to the name of
335 After C<hello> has run, Catalyst goes on to dispatch to the C<world>
336 action. This is the last action to be called, as Catalyst knows this
337 is an endpoint because we specified no C<:CaptureArgs> attribute. Nevertheless
338 we specify that this action expects an argument, but at this point we're
339 using C<:Args(1)> to do that. We could also have said C<:Args> or leave
340 it out alltogether, which would mean this action gets all arguments that
341 are there. This action's C<:Chained> attribute says C<hello> and tells
342 Catalyst that the C<hello> action in the current controller is it's
345 With this we have built a chain consisting of two public path parts.
346 C<hello> captures one part of the path as it's argument, and also specifies
347 the path root as it's parent. So this part is C</hello/$arg>. The next part
348 is the endpoint C<world>, expecting one argument. It sums up to the path
349 part C<world/$arg>. This leads to a complete chain of
350 C</hello/$arg/world/$arg> which is matched against the requested paths.
352 This example application would, if run and called by e.g.
353 C</hello/23/world/12>, set the stash value C<message> to C<Hello > and
354 the value C<arg_sum> to C<23>. The C<world> action would then append
355 C<World!> to C<message> and add C<12> to the stash's C<arg_sum> value.
356 For the sake of simplicity no view is shown. Instead we just put the
357 values of the stash into our body. So the output would look like:
362 And our test server would've given us this debugging output for the
366 [debug] "GET" request for "hello/23/world/12" from "127.0.0.1"
367 [debug] Path is "/greeting/world"
368 [debug] Arguments are "12"
369 [info] Request took 0.164113s (6.093/s)
370 .------------------------------------------+-----------.
372 +------------------------------------------+-----------+
373 | /greeting/hello | 0.000029s |
374 | /greeting/world | 0.000024s |
375 '------------------------------------------+-----------'
378 What would be common usecases of this dispatching technique? It gives the
379 possibility to split up logic that contains steps that each depend on each
380 other. An example would be, for example, a wiki path like
381 C</wiki/FooBarPage/rev/23/view>. This chain can be easily built with
384 sub wiki : PathPart('wiki') Chained('/') CaptureArgs(1) {
385 my ( $self, $c, $page_name ) = @_;
386 # load the page named $page_name and put the object
390 sub rev : PathPart('rev') Chained('wiki') CaptureArgs(1) {
391 my ( $self, $c, $revision_id ) = @_;
392 # use the page object in the stash to get at it's
393 # revision with number $revision_id
396 sub view : PathPart Chained('rev') Args(0) {
397 my ( $self, $c ) = @_;
398 # display the revision in our stash. An other option
399 # would be to forward a compatible object to the action
400 # that displays the default wiki pages, unless we want
401 # a different interface here, for example restore
405 It would now be possible to add other endpoints. For example C<restore> to
406 restore this specific revision as current state.
408 Also, you of course don't have to put all the chained actions in one
409 controller. The specification of the parent through C<:Chained> also takes
410 an absolute action path as it's argument. Just specify it with a leading
413 If you want, for example, to have actions for the public paths
414 C</foo/12/edit> and C</foo/12>, just specify two actions with
415 C<:PathPart('foo')> and C<:Chained('/')>. The handler for the former
416 path needs a C<:CaptureArgs(1)> attribute and a endpoint with
417 C<:PathPart('edit')> and C<:Chained('foo')>. For the latter path give
418 the action just a C<:Args(1)> to mark it as endpoint. This sums up to
419 this debugging output:
422 [debug] Loaded Path Part actions:
423 .-----------------------+------------------------------.
424 | Path Spec | Private |
425 +-----------------------+------------------------------+
426 | /foo/* | /controller/foo_view |
427 | /foo/*/edit | /controller/foo_load (1) |
428 | | => /controller/edit |
429 '-----------------------+------------------------------'
432 Here's a more detailed specification of the attributes belonging to
441 Sets the name of this part of the chain. If it is specified without
442 arguments, it takes the name of the action as default. So basically
443 C<sub foo :PathPart> and C<sub foo :PathPart('foo')> are identical.
444 This can also contain slashes to bind to a deeper level. An action
445 with C<sub bar :PathPart('foo/bar') :Chained('/')> would bind to
446 C</foo/bar/...>. If you don't specify C<:PathPart> it has the same
447 effect as using C<:PathPart>, it would default to the action name.
451 Has to be specified for every child in the chain. Possible values are
452 absolute and relative private action paths, with the relatives pointing
453 to the current controller, or a single slash C</> to tell Catalyst that
454 this is the root of a chain. The attribute C<:Chained> without aguments
455 also defaults to the C</> behaviour.
457 Due to the fact that you can specify an absolute path to the parent
458 action, it doesn't matter to Catalyst where that parent is located. So,
459 if your design requests it, you can redispatch a chain through every
460 controller or namespace you want.
462 Another interesting possibility gives C<:Chained('.')>, which chains
463 itself to an action with the path of the current controllers namespace.
466 # in MyApp::Controller::Foo
467 sub bar : Chained CaptureArgs(1) { ... }
469 # in MyApp::Controller::Foo::Bar
470 sub baz : Chained('.') Args(1) { ... }
472 This builds up a chain like C</bar/*/baz/*>. The specification of C<.>
473 as argument to Chained here chains the C<baz> action to an action with
474 the path of the current controller namespace, namely C</foo/bar>. That
475 action chains directly to C</>, so the above chain comes out as end
480 Also has to be specified for every part of the chain that is not an
481 endpoint. With this attribute Catalyst knows how many of the following
482 parts of the path (separated by C</>) this action wants to captures as
483 it's arguments. If it doesn't expect any, just specify C<:CaptureArgs(0)>.
484 The captures get passed to the action's C<@_> right after the context,
485 but you can also find them as array reference in
486 C<$c-E<gt>request-E<gt>captures-E<gt>[$level]>. The C<$level> is the
487 level of the action in the chain that captured the parts of the path.
489 An action that is part of a chain (read: that has a C<:Chained> attribute)
490 but has no C<:CaptureArgs> attribute is treated by Catalyst as a chain end.
494 By default, endpoints receive the rest of the arguments in the path. You
495 can tell Catalyst through C<:Args> explicitly how many arguments your
496 endpoint expects, just like you can with C<:CaptureArgs>. Note that this
497 also influences if this chain is invoked on a request. A chain with an
498 endpoint specifying one argument will only match if exactly one argument
501 You can specify an exact number of arguments like C<:Args(3)>, including
502 C<0>. If you just say C<:Args> without any arguments, it is the same as
503 leaving it out alltogether: The chain is matched independent of the number
504 of path parts after the endpoint.
506 Just like with C<:CaptureArgs>, the arguments get passed to the action in
507 C<@_> after the context object. They can also be reached through
508 C<$c-E<gt>request-E<gt>arguments>.
512 =head2 auto actions, dispatching and forwarding
514 Note that the list of C<auto> actions called depends on the private path
515 of the endpoint of the chain, not on the chained actions way. The C<auto>
516 actions will be run before the chain dispatching begins. In every other
517 aspect, C<auto> actions behave as documented.
519 The C<forward>ing to other actions does just what you would expect. But if
520 you C<detach> out of a chain, the rest of the chain will not get called
521 after the C<detach> returned.
525 Matt S Trout <mst@shadowcatsystems.co.uk>
529 This program is free software, you can redistribute it and/or modify it under
530 the same terms as Perl itself.