/ 
Leyland-1.000002
River stage zero No dependents
/ Leyland::Manual::Upgrading

NAME

Leyland::Manual::Upgrading - Guide for upgrading Leyland for existing applications

UPGRADING FROM VERSIONS 0.X.Y TO VERSIONS 1.X.Y

Since version 1.0.0 (i.e. 1.000000), several changes have been made which are not backwords compatible, and thus require making certain changes for existing applications.

The following is a list of changes that will require updating existing code, including the necessary code updates. Also included are several changes which you need to be aware of, even if they don't break backwords compatibility.

BACKWORDS COMPATIBILITY BREAKING CHANGES

  • Leyland now properly inherits Plack::Component, so it automatically gets the to_app() method from it. You no longer need define an application subroutine that calls the handle() method. On that note, the handle() method is renamed to call() in accordance with Plack::Component. This should be a simple change in your PSGI files: either change handle to call, or just call the to_app() method on the application object to create the application subroutine automatically.

    # previous code in app.psgi
my $leyland_app = MyLeylandApp->new;
my $plack_app = sub { $leyland_app->handle(shift) };

# new code in app.psgi
my $plack_app = MyLeylandApp->new->to_app;

# or, if you don't want to call to_app()
my $leyland_app = MeyLalndApp->new;
my $plack_app = sub { $leyland_app->call(shift) };

  • Leyland no longer provides its own logging mechanism. The Plack logger (psgix.logger) is now used, so you can use your preferred logging middleware. This doesn't change the syntax for writing to the log, but changes the way it is configured.

    # previous code in app.psgi
my $leyland_app = MyLeylandApp->new(config => {
	logger => {
		class => 'LogDispatch',
		opts => \%opts
	}
});

# new code in app.psgi
use Plack::Builder;
use Log::Dispatch;

my $app = MyLeylandApp->new->to_app;

builder {
	enable 'LogDispatch', logger => Log::Dispatch->new(%opts);
	$app;
};

# of course, you can use whichever logging middleware you want

  • Configuration of Leyland-specific options (such as views and locales) is now not done by using the config hash-ref that the PSGI file provides to the application object. Instead, the options are taken from the setup() method defined in the application class (if any). This method, which was previously used to make initializations upon creation of the application object, should now return a hash-ref of these configuration options. You should move your initialization work from the setup() method into the Moo/Moose based BUILD method (which should have been the right way to do it from the start anyway).

    # previous code in app.psgi
my $leyland_app = MyLeylandApp->new(config => {
	views => ['Tenjin'],
	locales => './i18n',
	something_app_specific => 'whatever'
});

# previous code in MyLeylandApp.pm
sub setup {
	# initialization work
}

# new code in app.psgi
my $leyland_app = MyLeylandApp->new(config => {
	something_app_specific => 'whatever'
})->to_app;

# new code in MyLeylandApp.pm
sub setup {
	return {
		views => ['Tenjin'],
		locales => ['./i18n']
	};
}

sub BUILD {
	# initialization work
}

  • The leyland command line utility for scaffolding a Leyland application is no longer available.

  • The forward() method of Leyland::Context will now only forward to a specific route method. If you don't tell it to which method to forward (e.g. forward('POST:/something')), it will assume forwarding to a GET method. This is a security measure so you don't accidentally forward to a "dangerous" route.

    # previous code in a controller
$c->forward('/something'); # might forward to a GET, POST, PUT, DELETE route, whichever is the first matching

# new code in a controller
$c->forward('/something'); # only forwards to GET routes, same as writing $c->forward('GET:/something')

POSSIBLY BACKWORDS COMPATIBILITY BREAKING CHANGES

The following changes might require updates to existing code:

  • There is no longer any need to provide the application object with the name of the application (which is then available in the "name" attribute). The name is now automatically calculated - it is the package name of the application. If your app used and relied on this attribute in some way, you should take that into account.

    # previous code in app.psgi
my $leyland_app = MyLeylandApp->new(config => { name => 'MyLeylandApp' });

# then somewhere else
my $name = $leyland_app->name; # = MyLeylandApp

# new code in app.psgi
my $leyland_app = MyLeylandApp->new->to_app;

# then somewhere else
my $name = $leyland_app->new; # = MyLeylandApp

  • Leyland no longer uses JSON::Any as its JSON object. It now uses JSON (which will automatically load JSON::XS if available). The interface should be the same, but you probably should be aware of this change. Note, also, that convert_blessed is now enabled on the JSON object.

  • Leyland is now Moo-based instead of Moose-based, so it is much lighter than previously. This change should not mean anything to existing applications, except that you can move them to Moo if you so wish. If your apps continue to use Moose, so will Leyland automatically.

WHAT'S NEXT?

This is the last stop of the Leyland manual. You can return to the table of contents if you wish or start writing your applications.

AUTHOR

Ido Perlmuter, <ido at ido50.net>

BUGS

Please report any bugs or feature requests to bug-Leyland at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Leyland. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Leyland::Manual::Upgrading

You can also look for information at:

LICENSE AND COPYRIGHT

Copyright 2010-2014 Ido Perlmuter.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.