3 Catalyst::Upgrading - Instructions for upgrading to the latest Catalyst
5 =head1 Upgrading to Catalyst TBA
7 =head2 Catalyst::Plugin::Unicode::Encoding is now core
9 The previously stand alone Unicode support module L<Catalyst::Plugin::Unicode::Encoding>
10 has been brought into core as a default plugin. Going forward, all you need is
11 to add a configuration setting for the encoding type. For example:
17 __PACKAGE__->config( encoding => 'UTF-8' );
19 Please note that this is different from the old stand alone plugin which applied
20 C<UTF-8> encoding by default (that is, if you did not set an explicit
21 C<encoding> configuration value, it assumed you wanted UTF-8). In order to
22 preserve backwards compatibility you will need to explicitly turn it on via the
23 configuration setting. THIS MIGHT CHANGE IN THE FUTURE, so please consider
24 starting to test your application with proper UTF-8 support and remove all those
25 crappy hacks you munged into the code because you didn't know the Plugin
28 For people that are using the Plugin, you will note a startup warning suggesting
29 that you can remove it from the plugin list. When you do so, please remember to
30 add the configuration setting, since you can no longer rely on the default being
31 UTF-8. We'll add it for you if you continue to use the stand alone plugin and
32 we detect this, but this backwards compatibility shim will likely be removed in
33 a few releases (trying to clean up the codebase after all).
35 If you have trouble with any of this, please bring it to the attention of the
36 Catalyst maintainer group.
38 =head2 basic async and event loop support
40 This version of L<Catalyst> offers some support for using L<AnyEvent> and
41 L<IO::Async> event loops in your application. These changes should work
42 fine for most applications however if you are already trying to perform
43 some streaming, minor changes in this area of the code might affect your
44 functionality. Please see L<Catalyst::Response\write_fh> for more and for a
47 We consider this feature experimental. We will try not to break it, but we
48 reserve the right to make necessary changes to fix major issues that people
49 run into when the use this functionality in the wild.
51 =head1 Upgrading to Catalyst 5.9
53 The major change is that L<Plack>, a toolkit for using the L<PSGI>
54 specification, now replaces most of the subclasses of L<Catalyst::Engine>. If
55 you are using one of the standard subclasses of L<Catalyst::Engine> this
56 should be a straightforward upgrade for you. It was a design goal for
57 this release to preserve as much backwards compatibility as possible.
58 However, since L<Plack> is different from L<Catalyst::Engine>, it is
59 possible that differences exist for edge cases. Therefore, we recommend
60 that care be taken with this upgrade and that testing should be greater
61 than would be the case with a minor point update. Please inform the
62 Catalyst developers of any problems so that we can fix them and
65 It is highly recommended that you become familiar with the L<Plack> ecosystem
66 and documentation. Being able to take advantage of L<Plack> development and
67 middleware is a major bonus to this upgrade. Documentation about how to
68 take advantage of L<Plack::Middleware> by writing your own C<< .psgi >> file
69 is contained in L<Catalyst::PSGI>.
71 If you have created a custom subclass of L<Catalyst:Engine>, you will
72 need to convert it to be a subclass of L<Plack::Handler>.
74 If you are using the L<Plack> engine, L<Catalyst::Engine::PSGI>, this new
75 release supersedes that code.
77 If you are using a subclass of L<Catalyst::Engine> that is aimed at
78 nonstandard or internal/testing uses, such as
79 L<Catalyst::Engine::Embeddable>, you should still be able to continue
82 Advice for specific subclasses of L<Catalyst::Engine> follows:
84 =head2 Upgrading the FastCGI Engine
86 No upgrade is needed if your myapp_fastcgi.pl script is already upgraded
87 to use L<Catalyst::Script::FastCGI>.
89 =head2 Upgrading the mod_perl / Apache Engines
91 The engines that are built upon the various iterations of mod_perl,
92 L<Catalyst::Engine::Apache::MP13> (for mod_perl 1, and Apache 1.x) and
93 L<Catalyst::Engine::Apache2::MP20> (for mod_perl 2, and Apache 2.x),
94 should be seamless upgrades and will work using using L<Plack::Handler::Apache1>
95 or L<Plack::Handler::Apache2> as required.
97 L<Catalyst::Engine::Apache2::MP19>, however, is no longer supported, as
98 Plack does not support mod_perl version 1.99. This is unlikely to be a
99 problem for anyone, as 1.99 was a brief beta-test release for mod_perl
100 2, and all users of mod_perl 1.99 are encouraged to upgrade to a
101 supported release of Apache 2 and mod_perl 2.
103 =head2 Upgrading the HTTP Engine
105 The default development server that comes with the L<Catalyst> distribution
106 should continue to work as expected with no changes as long as your C<myapp_server>
107 script is upgraded to use L<Catalyst::Script::HTTP>.
109 =head2 Upgrading the CGI Engine
111 If you were using L<Catalyst::Engine::CGI> there is no upgrade needed if your
112 myapp_cgi.pl script is already upgraded to use L<Catalyst::Script::CGI>.
114 =head2 Upgrading Catalyst::Engine::HTTP::Prefork
116 If you were using L<Catalyst::Engine::HTTP::Prefork> then L<Starman>
117 is automatically loaded. You should (at least) change your C<Makefile.PL>
118 to depend on Starman.
120 You can regenerate your C<myapp_server.pl> script with C<catalyst.pl>
121 and implement a C<MyApp::Script::Server> class that looks like this:
123 package MyApp::Script::Server;
125 use namespace::autoclean;
127 extends 'CatalystX::Script::Server::Starman';
131 This takes advantage of the new script system, and will add a number of
132 options to the standard server script as extra options are added by
135 More information about these options can be seen at
136 L<CatalystX::Script::Server::Starman/SYNOPSIS>.
138 An alternate route to implement this functionality is to write a simple .psgi
139 file for your application, and then use the L<plackup> utility to start the
142 =head2 Upgrading the PSGI Engine
144 If you were using L<Catalyst::Engine::PSGI>, this new release supersedes
145 this engine in supporting L<Plack>. By default the Engine is now always
146 L<Plack>. As a result, you can remove the dependency on
147 L<Catalyst::Engine::PSGI> in your C<Makefile.PL>.
149 Applications that were using L<Catalyst::Engine::PSGI>
150 previously should entirely continue to work in this release with no changes.
152 However, if you have an C<app.psgi> script, then you no longer need to
153 specify the PSGI engine. Instead, the L<Catalyst> application class now
154 has a new method C<psgi_app> which returns a L<PSGI> compatible coderef
155 which you can wrap in the middleware of your choice.
157 Catalyst will use the .psgi for your application if it is located in the C<home>
158 directory of the application.
160 For example, if you were using L<Catalyst::Engine::PSGI> in the past, you will
161 have written (or generated) a C<script/myapp.psgi> file similar to this one:
166 MyCatalystApp->setup_engine('PSGI');
169 enable ... # enable your desired middleware
170 sub { MyCatalystApp->run(@_) };
173 Instead, you now say:
179 enable ... #enable your desired middleware
180 MyCatalystApp->psgi_app;
183 In the simplest case:
185 MyCatalystApp->setup_engine('PSGI');
186 my $app = sub { MyCatalystApp->run(@_) }
190 my $app = MyCatalystApp->psgi_app(@_);
194 my $app = sub { MyCatalystApp->psgi_app(@_) };
195 # If you make ^^ this mistake, your app won't work, and will confuse the hell out of you!
197 You can now move C<< script/myapp.psgi >> to C<< myapp.psgi >>, and the built-in
198 Catalyst scripts and your test suite will start using your .psgi file.
200 B<NOTE:> If you rename your .psgi file without these modifications, then
201 any tests run via L<Catalyst::Test> will not be compatible with the new
202 release, and will result in the development server starting, rather than
203 the expected test running.
205 B<NOTE:> If you are directly accessing C<< $c->req->env >> to get the PSGI
206 environment then this accessor is moved to C<< $c->engine->env >>,
207 you will need to update your code.
209 =head2 Engines which are known to be broken
211 The following engines B<DO NOT> work as of Catalyst version 5.9. The
212 core team will be happy to work with the developers and/or users of
213 these engines to help them port to the new Plack/Engine system, but for
214 now, applications which are currently using these engines B<WILL NOT>
215 run without modification to the engine code.
219 =item Catalyst::Engine::Wx
221 =item Catalyst::Engine::Zeus
223 =item Catalyst::Engine::JobQueue::POE
225 =item Catalyst::Engine::XMPP2
227 =item Catalyst::Engine::SCGI
231 =head2 Engines with unknown status
233 The following engines are untested or have unknown compatibility.
234 Reports are highly encouraged:
238 =item Catalyst::Engine::Mojo
240 =item Catalyst::Engine::Server (marked as Deprecated)
242 =item Catalyst::Engine::HTTP::POE (marked as Deprecated)
246 =head2 Plack functionality
248 See L<Catalyst::PSGI>.
252 Tests should generally work the same in Catalyst 5.9, but there are
255 Previously, if using L<Catalyst::Test> and doing local requests (against
256 a local server), if the application threw an exception then this
257 exception propagated into the test.
259 This behavior has been removed, and now a 500 response will be returned
260 to the test. This change standardizes behavior, so that local test
261 requests behave similarly to remote requests.
263 =head2 Regex dispatch type is deprecated.
265 The Regex dispatchtype (L<Catalyst::DispatchType::Regex>) has been deprecated.
267 You are encouraged to move your application to Chained dispatch (L<Catalyst::DispatchType::Chained>).
269 If you cannot do so, please add a dependency to Catalyst::DispatchType::Regex to your application's
272 =head1 Upgrading to Catalyst 5.80
274 Most applications and plugins should run unaltered on Catalyst 5.80.
276 However, a lot of refactoring work has taken place, and several changes have
277 been made which could cause incompatibilities. If your application or plugin
278 is using deprecated code, or relying on side effects, then you could have
279 issues upgrading to this release.
281 Most issues found with existing components have been easy to
282 solve. This document provides a complete description of behavior changes
283 which may cause compatibility issues, and of new Catalyst warnings which
286 If you think you have found an upgrade-related issue which is not covered in
287 this document, please email the Catalyst list to discuss the problem.
289 =head1 Moose features
291 =head2 Application class roles
293 You can only apply method modifiers after the application's C<< ->setup >>
294 method has been called. This means that modifiers will not work with methods
295 run during the call to C<< ->setup >>.
297 See L<Catalyst::Manual::ExtendingCatalyst> for more information about using
298 L<Moose> in your applications.
300 =head2 Controller actions in Moose roles
302 You can use L<MooseX::MethodAttributes::Role> if you want to declare actions
305 =head2 Using Moose in Components
307 The correct way to use Moose in a component in a both forward and backwards
310 package TestApp::Controller::Root;
312 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
314 See L<Components which inherit from Moose::Object before Catalyst::Component>.
316 =head1 Known backwards compatibility breakages
318 =head2 Applications in a single file
320 Applications must be in their own file, and loaded at compile time. This
321 issue generally only affects the tests of CPAN distributions. Your
322 application will fail if you try to define an application inline in a
323 block, and use plugins which supply a C< new > method, then use that
324 application latter in tests within the same file.
326 This is due to the fact that Catalyst is inlining a new method on your
327 application class allowing it to be compatible with Moose. The method
328 used to do this changed in 5.80004 to avoid the possibility of reporting
329 an 'Unknown Error' if your application failed to compile.
331 =head2 Issues with Class::C3
333 Catalyst 5.80 uses the L<Algorithm::C3> method dispatch order. This is
334 built into Perl 5.10, and comes via L<Class::C3> for Perl 5.8. This
335 replaces L<NEXT> with L<Class::C3::Adopt::NEXT>, forcing all components
336 to resolve methods using C3, rather than the unpredictable dispatch
339 This issue manifests itself by your application failing to start due to an
340 error message about having a non-linear @ISA.
342 The Catalyst plugin most often causing this is
343 L<Catalyst::Plugin::Session::Store::FastMmap> - if you are using this
344 plugin and see issues, then please upgrade your plugins, as it has been
345 fixed. Note that Makefile.PL in the distribution will warn about known
346 incompatible components.
348 This issue can, however, be found in your own application - the only solution is
349 to go through each base class of the class the error was reported against, until
350 you identify the ones in conflict, and resolve them.
352 To be able to generate a linear @ISA, the list of superclasses for each
353 class must be resolvable using the C3 algorithm. Unfortunately, when
354 superclasses are being used as mixins (to add functionality used in your class),
355 and with multiple inheritance, it is easy to get this wrong.
357 Most common is the case of:
359 package Component1; # Note, this is the common case
360 use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
362 package Component2; # Accidentally saying it this way causes a failure
363 use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
366 use base qw/Component1 Component2/;
368 Any situation like this will cause your application to fail to start.
370 For additional documentation about this issue, and how to resolve it, see
371 L<Class::C3::Adopt::NEXT>.
373 =head2 Components which inherit from Moose::Object before Catalyst::Component
375 Moose components which say:
377 package TestApp::Controller::Example;
379 extends qw/Moose::Object Catalyst::Component/;
381 to use the constructor provided by Moose, while working (if you do some hacks
382 with the C< BUILDARGS > method), will not work with Catalyst 5.80 as
383 C<Catalyst::Component> inherits from C<Moose::Object>, and so C< @ISA > fails
386 The correct way to use Moose in a component in a both forward and backwards
389 package TestApp::Controller::Root;
391 BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
393 Note that the C< extends > declaration needs to occur in a begin block for
394 L<attributes> to operate correctly.
396 This way you do not inherit directly from C<Moose::Object>
397 yourself. Having components which do not inherit their constructor from
398 C<Catalyst::Component> is B<unsupported>, and has never been recommended,
399 therefore you're on your own if you're using this technique. You'll need
400 to detect the version of Catalyst your application is running, and deal
401 with it appropriately.
403 You also don't get the L<Moose::Object> constructor, and therefore attribute
404 initialization will not work as normally expected. If you want to use Moose
405 attributes, then they need to be made lazy to correctly initialize.
407 Note that this only applies if your component needs to maintain component
408 backwards compatibility for Catalyst versions before 5.71001 - in 5.71001
409 attributes work as expected, and the BUILD method is called normally
410 (although BUILDARGS is not).
412 If you depend on Catalyst 5.8, then B<all> Moose features work as expected.
414 You will also see this issue if you do the following:
416 package TestApp::Controller::Example;
418 use base 'Catalyst::Controller';
420 as C< use base > appends to @ISA.
422 =head3 use Moose in MyApp
424 Similar to the above, this will also fail:
433 If you need to use Moose in your application class (e.g. for method modifiers
434 etc.) then the correct technique is:
442 __PACKAGE__->config( name => 'MyApp' );
443 __PACKAGE__->setup(qw/
447 =head2 Anonymous closures installed directly into the symbol table
449 If you have any code which installs anonymous subroutine references directly
450 into the symbol table, you may encounter breakages. The simplest solution is
451 to use L<Sub::Name> to name the subroutine. Example:
453 # Original code, likely to break:
454 my $full_method_name = join('::', $package_name, $method_name);
455 *$full_method_name = sub { ... };
458 use Sub::Name 'subname';
459 my $full_method_name = join('::',$package_name, $method_name);
460 *$full_method_name = subname $full_method_name, sub { ... };
462 Additionally, you can take advantage of Catalyst's use of L<Class::MOP> and
463 install the closure using the appropriate metaclass. Example:
466 my $metaclass = Moose::Meta::Class->initialize($package_name);
467 $metaclass->add_method($method_name => sub { ... });
469 =head2 Hooking into application setup
471 To execute code during application start-up, the following snippet in MyApp.pm
475 my ($class, @args) = @_;
476 $class->NEXT::setup(@args);
477 ... # things to do after the actual setup
480 With Catalyst 5.80 this won't work anymore, because Catalyst no longer
481 uses NEXT.pm for method resolution. The functionality was only ever
482 originally operational as L<NEXT> remembers what methods have already
483 been called, and will not call them again.
485 Using this now causes infinite recursion between MyApp::setup and
486 Catalyst::setup, due to other backwards compatibility issues related to how
487 plugin setup works. Moose method modifiers like C<< before|after|around setup
488 => sub { ... }; >> also will not operate correctly on the setup method.
490 The right way to do it is this:
492 after setup_finalize => sub {
493 ... # things to do after the actual setup
496 The setup_finalize hook was introduced as a way to avoid this issue.
498 =head2 Components with a new method which returns false
500 Previously, if you had a component which inherited from Catalyst::COMPONENT,
501 but overrode the new method to return false, then your class's configuration
502 would be blessed into a hash on your behalf, and this would be returned from
503 the COMPONENT method.
505 This behavior makes no sense, and so has been removed. Implementing your own
506 C< new > method in components is B<highly> discouraged. Instead, you should
507 inherit the new method from Catalyst::Component, and use Moose's BUILD
508 functionality and/or Moose attributes to perform any construction work
509 necessary for your class.
511 =head2 __PACKAGE__->mk_accessor('meta');
513 Won't work due to a limitation of L<Moose>. This is currently being fixed
516 =head2 Class::Data::Inheritable side effects
518 Previously, writing to a class data accessor would copy the accessor method
519 down into your package.
521 This behavior has been removed. While the class data is still stored
522 per-class, it is stored on the metaclass of the class defining the accessor.
524 Therefore anything relying on the side effect of the accessor being copied down
527 The following test demonstrates the problem:
531 use base qw/Class::Data::Inheritable/;
532 __PACKAGE__->mk_classdata('foo');
537 use base qw/BaseClass/;
540 BaseClass->foo('base class');
541 Child->foo('sub class');
544 isnt(BaseClass->can('foo'), Child->can('foo'));
546 =head2 Extending Catalyst::Request or other classes in an ad hoc manner using mk_accessors
548 Previously, it was possible to add additional accessors to Catalyst::Request
549 (or other classes) by calling the mk_accessors class method.
551 This is no longer supported - users should make a subclass of the class whose
552 behavior they would like to change, rather than globally polluting the
555 =head2 Confused multiple inheritance with Catalyst::Component::COMPONENT
557 Previously, Catalyst's COMPONENT method would delegate to the method on
558 the right hand side, which could then delegate back again with
559 NEXT. This is poor practice, and in addition, makes no sense with C3
560 method dispatch order, and is therefore no longer supported.
562 If a COMPONENT method is detected in the inheritance hierarchy to the right
563 hand side of Catalyst::Component::COMPONENT, then the following warning
564 message will be emitted:
566 There is a COMPONENT method resolving after Catalyst::Component
569 The correct fix is to re-arrange your class's inheritance hierarchy so that the
570 COMPONENT method you would like to inherit is the first (left-hand most)
571 COMPONENT method in your @ISA.
573 =head2 Development server relying on environment variables
575 Previously, the development server would allow propagation of system
576 environment variables into the request environment, this has changed with the
577 adoption of Plack. You can use L<Plack::Middleware::ForceEnv> to achieve the
582 =head2 Actions in your application class
584 Having actions in your application class will now emit a warning at application
585 startup as this is deprecated. It is highly recommended that these actions are moved
586 into a MyApp::Controller::Root (as demonstrated by the scaffold application
587 generated by catalyst.pl).
589 This warning, also affects tests. You should move actions in your test,
590 creating a myTest::Controller::Root, like the following example:
592 package MyTest::Controller::Root;
597 use parent 'Catalyst::Controller';
599 __PACKAGE__->config(namespace => '');
602 my ( $self, $c ) = @_;
608 =head2 ::[MVC]:: naming scheme
610 Having packages called MyApp::[MVC]::XX is deprecated and can no longer be generated
613 This is still supported, but it is recommended that you rename your application
614 components to Model/View/Controller.
616 A warning will be issued at application startup if the ::[MVC]:: naming scheme is
619 =head2 Catalyst::Base
621 Any code using L<Catalyst::Base> will now emit a warning; this
622 module will be removed in a future release.
624 =head2 Methods in Catalyst::Dispatcher
626 The following methods in Catalyst::Dispatcher are implementation
627 details, which may change in the 5.8X release series, and therefore their use
628 is highly deprecated.
636 =item registered_dispatch_types
638 =item method_action_class
646 The first time one of these methods is called, a warning will be emitted:
648 Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
649 this will be removed in Catalyst 5.9
651 You should B<NEVER> be calling any of these methods from application code.
653 Plugin authors and maintainers whose plugins currently call these methods
654 should change to using the public API, or, if you do not feel the public API
655 adequately supports your use case, please email the development list to
656 discuss what API features you need so that you can be appropriately supported.
658 =head2 Class files with names that don't correspond to the packages they define
660 In this version of Catalyst, if a component is loaded from disk, but no
661 symbols are defined in that component's name space after it is loaded, this
662 warning will be issued:
664 require $class was successful but the package is not defined.
666 This is to protect against confusing bugs caused by mistyping package names,
667 and will become a fatal error in a future version.
669 Please note that 'inner packages' (via L<Devel::InnerPackage>) are still fully
670 supported; this warning is only issued when component file naming does not map
671 to B<any> of the packages defined within that component.
673 =head2 $c->plugin method
675 Calling the plugin method is deprecated, and calling it at run time is B<highly
678 Instead you are recommended to use L<Catalyst::Model::Adaptor> or similar to
679 compose the functionality you need outside of the main application name space.
681 Calling the plugin method will not be supported past Catalyst 5.81.