Catalyst::Upgrading(3)User Contributed Perl DocumentatioCatalyst::Upgrading(3)NAMECatalyst::Upgrading - Instructions for upgrading to the latest Catalyst
Upgrading to Catalyst 5.9
The major change is that Plack, a toolkit for using the PSGI
specification, now replaces most of the subclasses of Catalyst::Engine.
If you are using one of the standard subclasses of Catalyst::Engine
this should be a straightforward upgrade for you. It was a design goal
for this release to preserve as much backwards compatibility as
possible. However, since Plack is different from Catalyst::Engine, it
is possible that differences exist for edge cases. Therefore, we
recommend that care be taken with this upgrade and that testing should
be greater than would be the case with a minor point update. Please
inform the Catalyst developers of any problems so that we can fix them
and incorporate tests.
It is highly recommended that you become familiar with the Plack
ecosystem and documentation. Being able to take advantage of Plack
development and middleware is a major bonus to this upgrade.
Documentation about how to take advantage of Plack::Middleware by
writing your own ".psgi" file is contained in Catalyst::PSGI.
If you have created a custom subclass of <Catalyst:Engine>, you will
need to convert it to be a subclass of Plack::Handler.
If you are using the Plack engine, Catalyst::Engine::PSGI, this new
release supersedes that code.
If you are using a subclass of Catalyst::Engine that is aimed at
nonstandard or internal/testing uses, such as
Catalyst::Engine::Embeddable, you should still be able to continue
using that engine.
Advice for specific subclasses of Catalyst::Engine follows:
Upgrading the FastCGI Engine
No upgrade is needed if your myapp_fastcgi.pl script is already
upgraded to use Catalyst::Script::FastCGI.
Upgrading the mod_perl / Apache Engines
The engines that are built upon the various iterations of mod_perl,
Catalyst::Engine::Apache::MP13 (for mod_perl 1, and Apache 1.x) and
Catalyst::Engine::Apache2::MP20 (for mod_perl 2, and Apache 2.x),
should be seamless upgrades and will work using using
Plack::Handler::Apache1 or Plack::Handler::Apache2 as required.
Catalyst::Engine::Apache2::MP19, however, is no longer supported, as
Plack does not support mod_perl version 1.99. This is unlikely to be a
problem for anyone, as 1.99 was a brief beta-test release for mod_perl
2, and all users of mod_perl 1.99 are encouraged to upgrade to a
supported release of Apache 2 and mod_perl 2.
Upgrading the HTTP Engine
The default development server that comes with the Catalyst
distribution should continue to work as expected with no changes as
long as your "myapp_server" script is upgraded to use
Catalyst::Script::HTTP.
Upgrading the CGI Engine
If you were using Catalyst::Engine::CGI there is no upgrade needed if
your myapp_cgi.pl script is already upgraded to use
Catalyst::Script::CGI.
Upgrading Catalyst::Engine::HTTP::Prefork
If you were using Catalyst::Engine::HTTP::Prefork then Starman is
automatically loaded. You should (at least) change your "Makefile.PL"
to depend on Starman.
You can regenerate your "myapp_server.pl" script with "catalyst.pl" and
implement a "MyApp::Script::Server" class that looks like this:
package MyApp::Script::Server;
use Moose;
use namespace::autoclean;
extends 'CatalystX::Script::Server::Starman';
1;
This takes advantage of the new script system, and will add a number of
options to the standard server script as extra options are added by
Starman.
More information about these options can be seen at "SYNOPSIS" in
CatalystX::Script::Server::Starman.
An alternate route to implement this functionality is to write a simple
.psgi file for your application, and then use the plackup utility to
start the server.
Upgrading the PSGI Engine
If you were using Catalyst::Engine::PSGI, this new release supersedes
this engine in supporting Plack. By default the Engine is now always
Plack. As a result, you can remove the dependency on
Catalyst::Engine::PSGI in your "Makefile.PL".
Applications that were using Catalyst::Engine::PSGI previously should
entirely continue to work in this release with no changes.
However, if you have an "app.psgi" script, then you no longer need to
specify the PSGI engine. Instead, the Catalyst application class now
has a new method "psgi_app" which returns a PSGI compatible coderef
which you can wrap in the middleware of your choice.
Catalyst will use the .psgi for your application if it is located in
the "home" directory of the application.
For example, if you were using Catalyst::Engine::PSGI in the past, you
will have written (or generated) a "script/myapp.psgi" file similar to
this one:
use Plack::Builder;
use MyCatalytApp;
MyCatalystApp->setup_engine('PSGI');
builder {
enable ... # enable your desired middleware
sub { MyCatalystApp->run(@_) };
};
Instead, you now say:
use Plack::Builder;
use MyCatalystApp;
builder {
enable ... #enable your desired middleware
MyCatalystApp->psgi_app;
};
In the simplest case:
MyCatalystApp->setup_engine('PSGI');
my $app = sub { MyCatalystApp->run(@_) }
becomes
my $app = MyCatalystApp->psgi_app(@_);
NOT:
my $app = sub { MyCatalystApp->psgi_app(@_) };
# If you make ^^ this mistake, your app won't work, and will confuse the hell out of you!
You can now move "script/myapp.psgi" to "myapp.psgi", and the built-in
Catalyst scripts and your test suite will start using your .psgi file.
NOTE: If you rename your .psgi file without these modifications, then
any tests run via Catalyst::Test will not be compatible with the new
release, and will result in the development server starting, rather
than the expected test running.
NOTE: If you are directly accessing "$c->req->env" to get the PSGI
environment then this accessor is moved to "$c->engine->env", you will
need to update your code.
Engines which are known to be broken
The following engines DO NOT work as of Catalyst version 5.9. The core
team will be happy to work with the developers and/or users of these
engines to help them port to the new Plack/Engine system, but for now,
applications which are currently using these engines WILL NOT run
without modification to the engine code.
Catalyst::Engine::Wx
Catalyst::Engine::Zeus
Catalyst::Engine::JobQueue::POE
Catalyst::Engine::XMPP2
Catalyst::Engine::SCGI
Engines with unknown status
The following engines are untested or have unknown compatibility.
Reports are highly encouraged:
Catalyst::Engine::Mojo
Catalyst::Engine::Server (marked as Deprecated)
Catalyst::Engine::HTTP::POE (marked as Deprecated)
Plack functionality
See Catalyst::PSGI.
Tests in 5.9
Tests should generally work the same in Catalyst 5.9, but there are
some differences.
Previously, if using Catalyst::Test and doing local requests (against a
local server), if the application threw an exception then this
exception propagated into the test.
This behavior has been removed, and now a 500 response will be returned
to the test. This change standardizes behavior, so that local test
requests behave similarly to remote requests.
Upgrading to Catalyst 5.80
Most applications and plugins should run unaltered on Catalyst 5.80.
However, a lot of refactoring work has taken place, and several changes
have been made which could cause incompatibilities. If your application
or plugin is using deprecated code, or relying on side effects, then
you could have issues upgrading to this release.
Most issues found with existing components have been easy to solve.
This document provides a complete description of behavior changes which
may cause compatibility issues, and of new Catalyst warnings which
might be unclear.
If you think you have found an upgrade-related issue which is not
covered in this document, please email the Catalyst list to discuss the
problem.
Moose features
Application class roles
You can only apply method modifiers after the application's "->setup"
method has been called. This means that modifiers will not work with
methods run during the call to "->setup".
See Catalyst::Manual::ExtendingCatalyst for more information about
using Moose in your applications.
Controller actions in Moose roles
You can use MooseX::MethodAttributes::Role if you want to declare
actions inside Moose roles.
Using Moose in Components
The correct way to use Moose in a component in a both forward and
backwards compatible way is:
package TestApp::Controller::Root;
use Moose;
BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
See "Components which inherit from Moose::Object before
Catalyst::Component".
Known backwards compatibility breakages
Applications in a single file
Applications must be in their own file, and loaded at compile time.
This issue generally only affects the tests of CPAN distributions. Your
application will fail if you try to define an application inline in a
block, and use plugins which supply a " new " method, then use that
application latter in tests within the same file.
This is due to the fact that Catalyst is inlining a new method on your
application class allowing it to be compatible with Moose. The method
used to do this changed in 5.80004 to avoid the possibility of
reporting an 'Unknown Error' if your application failed to compile.
Issues with Class::C3
Catalyst 5.80 uses the Algorithm::C3 method dispatch order. This is
built into Perl 5.10, and comes via Class::C3 for Perl 5.8. This
replaces NEXT with Class::C3::Adopt::NEXT, forcing all components to
resolve methods using C3, rather than the unpredictable dispatch order
of NEXT.
This issue manifests itself by your application failing to start due to
an error message about having a non-linear @ISA.
The Catalyst plugin most often causing this is
Catalyst::Plugin::Session::Store::FastMmap - if you are using this
plugin and see issues, then please upgrade your plugins, as it has been
fixed. Note that Makefile.PL in the distribution will warn about known
incompatible components.
This issue can, however, be found in your own application - the only
solution is to go through each base class of the class the error was
reported against, until you identify the ones in conflict, and resolve
them.
To be able to generate a linear @ISA, the list of superclasses for each
class must be resolvable using the C3 algorithm. Unfortunately, when
superclasses are being used as mixins (to add functionality used in
your class), and with multiple inheritance, it is easy to get this
wrong.
Most common is the case of:
package Component1; # Note, this is the common case
use base qw/Class::Accessor::Fast Class::Data::Inheritable/;
package Component2; # Accidentally saying it this way causes a failure
use base qw/Class::Data::Inheritable Class::Accessor::Fast/;
package GoesBang;
use base qw/Component1 Component2/;
Any situation like this will cause your application to fail to start.
For additional documentation about this issue, and how to resolve it,
see Class::C3::Adopt::NEXT.
Components which inherit from Moose::Object before Catalyst::Component
Moose components which say:
package TestApp::Controller::Example;
use Moose;
extends qw/Moose::Object Catalyst::Component/;
to use the constructor provided by Moose, while working (if you do some
hacks with the " BUILDARGS " method), will not work with Catalyst 5.80
as "Catalyst::Component" inherits from "Moose::Object", and so @ISA
fails to linearize.
The correct way to use Moose in a component in a both forward and
backwards compatible way is:
package TestApp::Controller::Root;
use Moose;
BEGIN { extends 'Catalyst::Component' }; # Or ::Controller, or whatever
Note that the " extends " declaration needs to occur in a begin block
for attributes to operate correctly.
This way you do not inherit directly from "Moose::Object" yourself.
Having components which do not inherit their constructor from
"Catalyst::Component" is unsupported, and has never been recommended,
therefore you're on your own if you're using this technique. You'll
need to detect the version of Catalyst your application is running, and
deal with it appropriately.
You also don't get the Moose::Object constructor, and therefore
attribute initialization will not work as normally expected. If you
want to use Moose attributes, then they need to be made lazy to
correctly initialize.
Note that this only applies if your component needs to maintain
component backwards compatibility for Catalyst versions before 5.71001
- in 5.71001 attributes work as expected, and the BUILD method is
called normally (although BUILDARGS is not).
If you depend on Catalyst 5.8, then all Moose features work as
expected.
You will also see this issue if you do the following:
package TestApp::Controller::Example;
use Moose;
use base 'Catalyst::Controller';
as " use base " appends to @ISA.
use Moose in MyApp
Similar to the above, this will also fail:
package MyApp;
use Moose;
use Catalyst qw/
ConfigLoader
/;
__PACKAGE__->setup;
If you need to use Moose in your application class (e.g. for method
modifiers etc.) then the correct technique is:
package MyApp;
use Moose;
use Catalyst;
extends 'Catalyst';
__PACKAGE__->config( name => 'MyApp' );
__PACKAGE__->setup(qw/
ConfigLoader
/);
Anonymous closures installed directly into the symbol table
If you have any code which installs anonymous subroutine references
directly into the symbol table, you may encounter breakages. The
simplest solution is to use Sub::Name to name the subroutine. Example:
# Original code, likely to break:
my $full_method_name = join('::', $package_name, $method_name);
*$full_method_name = sub { ... };
# Fixed Code
use Sub::Name 'subname';
my $full_method_name = join('::',$package_name, $method_name);
*$full_method_name = subname $full_method_name, sub { ... };
Additionally, you can take advantage of Catalyst's use of Class::MOP
and install the closure using the appropriate metaclass. Example:
use Class::MOP;
my $metaclass = Moose::Meta::Class->initialize($package_name);
$metaclass->add_method($method_name => sub { ... });
Hooking into application setup
To execute code during application start-up, the following snippet in
MyApp.pm used to work:
sub setup {
my ($class, @args) = @_;
$class->NEXT::setup(@args);
... # things to do after the actual setup
}
With Catalyst 5.80 this won't work anymore, because Catalyst no longer
uses NEXT.pm for method resolution. The functionality was only ever
originally operational as NEXT remembers what methods have already been
called, and will not call them again.
Using this now causes infinite recursion between MyApp::setup and
Catalyst::setup, due to other backwards compatibility issues related to
how plugin setup works. Moose method modifiers like
"before|after|around setup => sub { ... };" also will not operate
correctly on the setup method.
The right way to do it is this:
after setup_finalize => sub {
... # things to do after the actual setup
};
The setup_finalize hook was introduced as a way to avoid this issue.
Components with a new method which returns false
Previously, if you had a component which inherited from
Catalyst::COMPONENT, but overrode the new method to return false, then
your class's configuration would be blessed into a hash on your behalf,
and this would be returned from the COMPONENT method.
This behavior makes no sense, and so has been removed. Implementing
your own " new " method in components is highly discouraged. Instead,
you should inherit the new method from Catalyst::Component, and use
Moose's BUILD functionality and/or Moose attributes to perform any
construction work necessary for your class.
__PACKAGE__->mk_accessor('meta');
Won't work due to a limitation of Moose. This is currently being fixed
inside Moose.
Class::Data::Inheritable side effects
Previously, writing to a class data accessor would copy the accessor
method down into your package.
This behavior has been removed. While the class data is still stored
per-class, it is stored on the metaclass of the class defining the
accessor.
Therefore anything relying on the side effect of the accessor being
copied down will be broken.
The following test demonstrates the problem:
{
package BaseClass;
use base qw/Class::Data::Inheritable/;
__PACKAGE__->mk_classdata('foo');
}
{
package Child;
use base qw/BaseClass/;
}
BaseClass->foo('base class');
Child->foo('sub class');
use Test::More;
isnt(BaseClass->can('foo'), Child->can('foo'));
Extending Catalyst::Request or other classes in an ad hoc manner using
mk_accessors
Previously, it was possible to add additional accessors to
Catalyst::Request (or other classes) by calling the mk_accessors class
method.
This is no longer supported - users should make a subclass of the class
whose behavior they would like to change, rather than globally
polluting the Catalyst objects.
Confused multiple inheritance with Catalyst::Component::COMPONENT
Previously, Catalyst's COMPONENT method would delegate to the method on
the right hand side, which could then delegate back again with NEXT.
This is poor practice, and in addition, makes no sense with C3 method
dispatch order, and is therefore no longer supported.
If a COMPONENT method is detected in the inheritance hierarchy to the
right hand side of Catalyst::Component::COMPONENT, then the following
warning message will be emitted:
There is a COMPONENT method resolving after Catalyst::Component
in ${next_package}.
The correct fix is to re-arrange your class's inheritance hierarchy so
that the COMPONENT method you would like to inherit is the first (left-
hand most) COMPONENT method in your @ISA.
Development server relying on environment variables
Previously, the development server would allow propagation of system
environment variables into the request environment, this has changed
with the adoption of Plack. You can use Plack::Middleware::ForceEnv to
achieve the same effect.
WARNINGS
Actions in your application class
Having actions in your application class will now emit a warning at
application startup as this is deprecated. It is highly recommended
that these actions are moved into a MyApp::Controller::Root (as
demonstrated by the scaffold application generated by catalyst.pl).
This warning, also affects tests. You should move actions in your test,
creating a myTest::Controller::Root, like the following example:
package MyTest::Controller::Root;
use strict;
use warnings;
use parent 'Catalyst::Controller';
__PACKAGE__->config(namespace => '');
sub action : Local {
my ( $self, $c ) = @_;
$c->do_something;
}
1;
::[MVC]:: naming scheme
Having packages called MyApp::[MVC]::XX is deprecated and can no longer
be generated by catalyst.pl
This is still supported, but it is recommended that you rename your
application components to Model/View/Controller.
A warning will be issued at application startup if the ::[MVC]:: naming
scheme is in use.
Catalyst::Base
Any code using Catalyst::Base will now emit a warning; this module will
be removed in a future release.
Methods in Catalyst::Dispatcher
The following methods in Catalyst::Dispatcher are implementation
details, which may change in the 5.8X release series, and therefore
their use is highly deprecated.
tree
dispatch_types
registered_dispatch_types
method_action_class
action_hash
container_hash
The first time one of these methods is called, a warning will be
emitted:
Class $class is calling the deprecated method Catalyst::Dispatcher::$public_method_name,
this will be removed in Catalyst 5.9
You should NEVER be calling any of these methods from application code.
Plugin authors and maintainers whose plugins currently call these
methods should change to using the public API, or, if you do not feel
the public API adequately supports your use case, please email the
development list to discuss what API features you need so that you can
be appropriately supported.
Class files with names that don't correspond to the packages they define
In this version of Catalyst, if a component is loaded from disk, but no
symbols are defined in that component's name space after it is loaded,
this warning will be issued:
require $class was successful but the package is not defined.
This is to protect against confusing bugs caused by mistyping package
names, and will become a fatal error in a future version.
Please note that 'inner packages' (via Devel::InnerPackage) are still
fully supported; this warning is only issued when component file naming
does not map to any of the packages defined within that component.
$c->plugin method
Calling the plugin method is deprecated, and calling it at run time is
highly deprecated.
Instead you are recommended to use Catalyst::Model::Adaptor or similar
to compose the functionality you need outside of the main application
name space.
Calling the plugin method will not be supported past Catalyst 5.81.
perl v5.14.2 2012-03-08 Catalyst::Upgrading(3)