3 Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst
5 =head1 Upgrading to Catalyst 5.9
7 The major change is that L<Plack>, a toolkit for using the L<PSGI>
8 specification, now replaces most of the subclasses of L<Catalyst::Engine>. If
9 you are using one of the standard subclasses of L<Catalyst::Engine> this
10 should be a straightforward upgrade for you. It was a design goal for
11 this release to preserve as much backwards compatibility as possible.
12 However, since L<Plack> is different from L<Catalyst::Engine>, it is
13 possible that differences exist for edge cases. Therefore, we recommend
14 that care be taken with this upgrade and that testing should be greater
15 than would be the case with a minor point update. Please inform the
16 Catalyst developers of any problems so that we can fix them and
19 It is highly recommended that you become familiar with the L<Plack> ecosystem
20 and documentation. Being able to take advantage of L<Plack> development and
21 middleware is a major bonus to this upgrade. Documentation about how to
22 take advantage of L<Plack::Middleware> by writing your own C<< .psgi >> file
23 is contained in L<Catalyst::PSGI>.
25 If you have created a custom subclass of L<Catalyst:Engine>, you will
26 need to convert it to be a subclass of L<Plack::Handler>.
28 If you are using the L<Plack> engine, L<Catalyst::Engine::PSGI>, this new
29 release supersedes that code.
31 If you are using a subclass of L<Catalyst::Engine> that is aimed at
32 nonstandard or internal/testing uses, such as
33 L<Catalyst::Engine::Embeddable>, you should still be able to continue
36 Advice for specific subclasses of L<Catalyst::Engine> follows:
38 =head2 Upgrading the FastCGI Engine
40 No upgrade is needed if your myapp_fastcgi.pl script is already upgraded
41 to use L<Catalyst::Script::FastCGI>.
43 =head2 Upgrading the mod_perl / Apache Engines
45 The engines that are built upon the various iterations of mod_perl,
46 L<Catalyst::Engine::Apache::MP13> (for mod_perl 1, and Apache 1.x) and
47 L<Catalyst::Engine::Apache2::MP20> (for mod_perl 2, and Apache 2.x),
48 should be seamless upgrades and will work using using L<Plack::Handler::Apache1>
49 or L<Plack::Handler::Apache2> as required.
51 L<Catalyst::Engine::Apache2::MP19>, however, is no longer supported, as
52 Plack does not support mod_perl version 1.99. This is unlikely to be a
53 problem for anyone, as 1.99 was a brief beta-test release for mod_perl
54 2, and all users of mod_perl 1.99 are encouraged to upgrade to a
55 supported release of Apache 2 and mod_perl 2.
57 =head2 Upgrading the HTTP Engine
59 The default development server that comes with the L<Catalyst> distribution
60 should continue to work as expected with no changes as long as your C<myapp_server>
61 script is upgraded to use L<Catalyst::Script::HTTP>.
63 =head2 Upgrading the CGI Engine
65 If you were using L<Catalyst::Engine::CGI> there is no upgrade needed if your
66 myapp_cgi.pl script is already upgraded to use L<Catalyst::Script::CGI>.
68 =head2 Upgrading the Preforking Engine
70 If you were using L<Catalyst::Engine::HTTP::Prefork> then L<Starman>
71 is automatically loaded. You should (at least) change your C<Makefile.PL>
74 You can regenerate your C<myapp_server.pl> script with C<catalyst.pl>
75 and implement a C<MyApp::Script::Server> class that looks like this:
77 package MyApp::Script::Server;
79 use namespace::autoclean;
81 extends 'CatalystX::Script::Server::Starman';
85 This takes advantage of the new script system, and will add a number of
86 options to the standard server script as extra options are added by
89 More information about these options can be seen at
90 L<CatalystX::Script::Server::Starman/SYNOPSIS>.
92 An alternate route to implement this functionality is to write a simple .psgi
93 file for your application, and then use the L<plackup> utility to start the
96 =head2 Upgrading the PSGI Engine
98 If you were using L<Catalyst::Engine::PSGI>, this new release supersedes
99 this engine in supporting L<Plack>. By default the Engine is now always
100 L<Plack>. As a result, you can remove the dependency on
101 L<Catalyst::Engine::PSGI> in your C<Makefile.PL>.
103 Applications that were using L<Catalyst::Engine::PSGI>
104 previously should entirely continue to work in this release with no changes.
106 However, if you have an C<app.psgi> script, then you no longer need to
107 specify the PSGI engine. Instead, the L<Catalyst> application class now
108 has a new method C<psgi_app> which returns a L<PSGI> compatible coderef
109 which you can wrap in the middleware of your choice.
111 Catalyst will use the .psgi for your application if it is located in the C<home>
112 directory of the application.
114 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
115 have written (or generated) a C<script/myapp.psgi> file similar to this one:
120 MyCatalystApp->setup_engine('PSGI');
123 enable ... # enable your desired middleware
124 sub { MyCatalystApp->run(@_) };
127 Instead, you now say:
133 enable ... #enable your desired middleware
134 MyCatalystApp->psgi_app;
137 In the simplest case:
139 MyCatalystApp->setup_engine('PSGI');
140 my $app = sub { MyCatalystApp->run(@_) }
144 MyCatalystApp->setup_engine('PSGI');
145 my $app = MyCatalystApp->psgi_app(@_);
149 my $app = sub { MyCatalystApp->psgi_app(@_) };
150 # If you make ^^ this mistake, your app won't work, and will confuse the hell out of you!
152 You can now move C<< script/myapp.psgi >> to C<< myapp.psgi >>, and the built-in
153 Catalyst scripts and your test suite will start using your .psgi file.
155 B<NOTE:> If you rename your .psgi file without these modifications, then
156 any tests run via L<Catalyst::Test> will not be compatible with the new
157 release, and will result in the development server starting, rather than
158 the expected test running.
160 =head2 Engines which are known to be broken
162 The following engines B<DO NOT> work as of Catalyst version 5.9. The
163 core team will be happy to work with the developers and/or users of
164 these engines to help them port to the new Plack/Engine system, but for
165 now, applications which are currently using these engines B<WILL NOT>
166 run without modification to the engine code.
170 =item Catalyst::Engine::Wx
172 =item Catalyst::Engine::Zeus
174 =item Catalyst::Engine::JobQueue::POE
176 =item Catalyst::Engine::XMPP2
178 =item Catalyst::Engine::SCGI
182 =head2 Engines with unknown status
184 The following engines are untested or have unknown compatibility.
185 Reports are highly encouraged:
189 =item Catalyst::Engine::Mojo
191 =item Catalyst::Engine::Server (marked as Deprecated)
193 =item Catalyst::Engine::HTTP::POE (marked as Deprecated)
197 =head2 Specifying the engine in the call to ->setup
201 =head2 Plack functionality
203 See L<Catalyst::PSGI>.
207 Tests should generally work the same in Catalyst 5.9, but there are
210 Previously, if using L<Catalyst::Test> and doing local requests (against
211 a local server), if the application threw an exception then this
212 exception propagated into the test.
214 This behavior has been removed, and now a 500 response will be returned
215 to the test. This change standardizes behavior, so that local test
216 requests behave similarly to remote requests.
218 =head1 Upgrading to Catalyst 5.80
220 Most applications and plugins should run unaltered on Catalyst 5.80.
222 However, a lot of refactoring work has taken place, and several changes have
223 been made which could cause incompatibilities. If your application or plugin
224 is using deprecated code, or relying on side effects, then you could have
225 issues upgrading to this release.
227 Most issues found with pre-existing components have been easy to
228 solve. This document provides a complete description of behavior changes
229 which may cause compatibility issues, and of new Catalyst warnings which
232 If you think you have found an upgrade-related issue which is not covered in
233 this document, please email the Catalyst list to discuss the problem.
235 =head1 Moose features
237 =head2 Application class roles
239 You can only apply method modifiers after the application's C<< ->setup >>
240 method has been called. This means that modifiers will not work with methods
241 run during the call to C<< ->setup >>.
243 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
244 L<Moose> in your applications.
246 =head2 Controller actions in Moose roles
248 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
251 =head2 Using Moose in Components
253 The correct way to use Moose in a component in a both forward and backwards
256 package TestApp::Controller::Root;
258 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
260 See L<Components which inherit from Moose::Object before Catalyst::Component>.
262 =head1 Known backwards compatibility breakages
264 =head2 Applications in a single file
266 Applications must be in their own file, and loaded at compile time. This
267 issue generally only affects the tests of CPAN distributions. Your
268 application will fail if you try to define an application inline in a
269 block, and use plugins which supply a C< new > method, then use that
270 application latter in tests within the same file.
272 This is due to the fact that Catalyst is inlining a new method on your
273 application class allowing it to be compatible with Moose. The method
274 used to do this changed in 5.80004 to avoid the possibility of reporting
275 an 'Unknown Error' if your application failed to compile.
277 =head2 Issues with Class::C3
279 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
280 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
281 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
282 to resolve methods using C3, rather than the unpredictable dispatch
285 This issue is characterised by your application failing to start due to an
286 error message about having a non-linear @ISA.
288 The Catalyst plugin most often causing this is
289 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
290 plugin and see issues, then please upgrade your plugins, as it has been
291 fixed. Note that Makefile.PL in the distribution will warn about known
292 incompatible components.
294 This issue can, however, be found in your own application - the only solution is
295 to go through each base class of the class the error was reported against, until
296 you identify the ones in conflict, and resolve them.
298 To be able to generate a linear @ISA, the list of superclasses for each
299 class must be resolvable using the C3 algorithm. Unfortunately, when
300 superclasses are being used as mixins (to add functionality used in your class),
301 and with multiple inheritance, it is easy to get this wrong.
303 Most common is the case of:
305 package Component1; # Note, this is the common case
306 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
308 package Component2; # Accidentally saying it this way causes a failure
309 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
312 use base qw/Component1 Component2/;
314 Any situation like this will cause your application to fail to start.
316 For additional documentation about this issue, and how to resolve it, see
317 L<Class::C3::Adopt::NEXT>.
319 =head2 Components which inherit from Moose::Object before Catalyst::Component
321 Moose components which say:
323 package TestApp::Controller::Example;
325 extends qw/Moose::Object Catalyst::Component/;
327 to use the constructor provided by Moose, while working (if you do some hacks
328 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
329 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
332 The correct way to use Moose in a component in a both forward and backwards
335 package TestApp::Controller::Root;
337 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
339 Note that the C< extends > declaration needs to occur in a begin block for
340 L<attributes> to operate correctly.
342 This way you do not inherit directly from C<Moose::Object>
343 yourself. Having components which do not inherit their constructor from
344 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
345 therefore you're on your own if you're using this technique. You'll need
346 to detect the version of Catalyst your application is running, and deal
347 with it appropriately.
349 You also don't get the L<Moose::Object> constructor, and therefore attribute
350 initialization will not work as normally expected. If you want to use Moose
351 attributes, then they need to be made lazy to correctly initialize.
353 Note that this only applies if your component needs to maintain component
354 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
355 attributes work as expected, and the BUILD method is called normally
356 (although BUILDARGS is not).
358 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
360 You will also see this issue if you do the following:
362 package TestApp::Controller::Example;
364 use base 'Catalyst::Controller';
366 as C< use base > appends to @ISA.
368 =head3 use Moose in MyApp
370 Similar to the above, this will also fail:
379 If you need to use Moose in your application class (e.g. for method modifiers
380 etc.) then the correct technique is:
388 __PACKAGE__->config( name => 'MyApp' );
389 __PACKAGE__->setup(qw/
393 =head2 Anonymous closures installed directly into the symbol table
395 If you have any code which installs anonymous subroutine references directly
396 into the symbol table, you may encounter breakages. The simplest solution is
397 to use L<Sub::Name> to name the subroutine. Example:
399 # Original code, likely to break:
400 my $full_method_name = join('::', $package_name, $method_name);
401 *$full_method_name = sub { ... };
404 use Sub::Name 'subname';
405 my $full_method_name = join('::',$package_name, $method_name);
406 *$full_method_name = subname $full_method_name, sub { ... };
408 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
409 install the closure using the appropriate metaclass. Example:
412 my $metaclass = Moose::Meta::Class->initialize($package_name);
413 $metaclass->add_method($method_name => sub { ... });
415 =head2 Hooking into application setup
417 To execute code during application start-up, the following snippet in MyApp.pm
421 my ($class, @args) = @_;
422 $class->NEXT::setup(@args);
423 ... # things to do after the actual setup
426 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
427 uses NEXT.pm for method resolution. The functionality was only ever
428 originally operational as L<NEXT> remembers what methods have already
429 been called, and will not call them again.
431 Using this now causes infinite recursion between MyApp::setup and
432 Catalyst::setup, due to other backwards compatibility issues related to how
433 plugin setup works. Moose method modifiers like C<< before|after|around setup
434 => sub { ... }; >> also will not operate correctly on the setup method.
436 The right way to do it is this:
438 after setup_finalize => sub {
439 ... # things to do after the actual setup
442 The setup_finalize hook was introduced as a way to avoid this issue.
444 =head2 Components with a new method which returns false
446 Previously, if you had a component which inherited from Catalyst::COMPONENT,
447 but overrode the new method to return false, then your class's configuration
448 would be blessed into a hash on your behalf, and this would be returned from
449 the COMPONENT method.
451 This behavior makes no sense, and so has been removed. Implementing your own
452 C< new > method in components is B<highly> discouraged. Instead, you should
453 inherit the new method from Catalyst::Component, and use Moose's BUILD
454 functionality and/or Moose attributes to perform any construction work
455 necessary for your class.
457 =head2 __PACKAGE__->mk_accessor('meta');
459 Won't work due to a limitation of L<Moose>. This is currently being fixed
462 =head2 Class::Data::Inheritable side effects
464 Previously, writing to a class data accessor would copy the accessor method
465 down into your package.
467 This behavior has been removed. While the class data is still stored
468 per-class, it is stored on the metaclass of the class defining the accessor.
470 Therefore anything relying on the side effect of the accessor being copied down
473 The following test demonstrates the problem:
477 use base qw/Class::Data::Inheritable/;
478 __PACKAGE__->mk_classdata('foo');
483 use base qw/BaseClass/;
486 BaseClass->foo('base class');
487 Child->foo('sub class');
490 isnt(BaseClass->can('foo'), Child->can('foo'));
492 =head2 Extending Catalyst::Request or other classes in an ad-hoc manner using mk_accessors
494 Previously, it was possible to add additional accessors to Catalyst::Request
495 (or other classes) by calling the mk_accessors class method.
497 This is no longer supported - users should make a subclass of the class whose
498 behavior they would like to change, rather than globally polluting the
501 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
503 Previously, Catalyst's COMPONENT method would delegate to the method on
504 the right hand side, which could then delegate back again with
505 NEXT. This is poor practice, and in addition, makes no sense with C3
506 method dispatch order, and is therefore no longer supported.
508 If a COMPONENT method is detected in the inheritance hierarchy to the right
509 hand side of Catalyst::Component::COMPONENT, then the following warning
510 message will be emitted:
512 There is a COMPONENT method resolving after Catalyst::Component
515 The correct fix is to re-arrange your class's inheritance hierarchy so that the
516 COMPONENT method you would like to inherit is the first (left-hand most)
517 COMPONENT method in your @ISA.
521 =head2 Actions in your application class
523 Having actions in your application class will now emit a warning at application
524 startup as this is deprecated. It is highly recommended that these actions are moved
525 into a MyApp::Controller::Root (as demonstrated by the scaffold application
526 generated by catalyst.pl).
528 This warning, also affects tests. You should move actions in your test,
529 creating a myTest::Controller::Root, like the following example:
531 package MyTest::Controller::Root;
536 use parent 'Catalyst::Controller';
538 __PACKAGE__->config(namespace => '');
541 my ( $self, $c ) = @_;
547 =head2 ::[MVC]:: naming scheme
549 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
552 This is still supported, but it is recommended that you rename your application
553 components to Model/View/Controller.
555 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
558 =head2 Catalyst::Base
560 Any code using L<Catalyst::Base> will now emit a warning; this
561 module will be removed in a future release.
563 =head2 Methods in Catalyst::Dispatcher
565 The following methods in Catalyst::Dispatcher are implementation
566 details, which may change in the 5.8X release series, and therefore their use
567 is highly deprecated.
575 =item registered_dispatch_types
577 =item method_action_class
585 The first time one of these methods is called, a warning will be emitted:
587 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
588 this will be removed in Catalyst 5.9
590 You should B<NEVER> be calling any of these methods from application code.
592 Plugin authors and maintainers whose plugins currently call these methods
593 should change to using the public API, or, if you do not feel the public API
594 adequately supports your use case, please email the development list to
595 discuss what API features you need so that you can be appropriately supported.
597 =head2 Class files with names that don't correspond to the packages they define
599 In this version of Catalyst, if a component is loaded from disk, but no
600 symbols are defined in that component's name space after it is loaded, this
601 warning will be issued:
603 require $class was successful but the package is not defined.
605 This is to protect against confusing bugs caused by mistyping package names,
606 and will become a fatal error in a future version.
608 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
609 supported; this warning is only issued when component file naming does not map
610 to B<any> of the packages defined within that component.
612 =head2 $c->plugin method
614 Calling the plugin method is deprecated, and calling it at run time is B<highly
617 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
618 compose the functionality you need outside of the main application name space.
620 Calling the plugin method will not be supported past Catalyst 5.81.