class Quails::Railtie
Quails::Railtie
is the core of the Quails
framework and provides several hooks to extend Quails
and/or modify the initialization process.
Every major component of Quails
(Action Mailer, Action Controller, Active Record
, etc.) implements a railtie. Each of them is responsible for their own initialization. This makes Quails
itself absent of any component hooks, allowing other components to be used in place of any of the Quails
defaults.
Developing a Quails
extension does not require implementing a railtie, but if you need to interact with the Quails
framework during or after boot, then a railtie is needed.
For example, an extension doing any of the following would need a railtie:
-
creating initializers
-
configuring a
Quails
framework for the application, like setting a generator -
adding
config.*
keys to the environment -
setting up a subscriber with
ActiveSupport::Notifications
-
adding Rake tasks
Creating a Railtie
¶ ↑
To extend Quails
using a railtie, create a subclass of Quails::Railtie
. This class must be loaded during the Quails
boot process, and is conventionally called MyNamespace::Railtie
.
The following example demonstrates an extension which can be used with or without Quails
.
# lib/my_gem/railtie.rb module MyGem class Railtie < Quails::Railtie end end # lib/my_gem.rb require 'my_gem/railtie' if defined?(Quails)
Initializers¶ ↑
To add an initialization step to the Quails
boot process from your railtie, just define the initialization code with the initializer
macro:
class MyRailtie < Quails::Railtie initializer "my_railtie.configure_quails_initialization" do # some initialization behavior end end
If specified, the block can also receive the application object, in case you need to access some application-specific configuration, like middleware:
class MyRailtie < Quails::Railtie initializer "my_railtie.configure_quails_initialization" do |app| app.middleware.use MyRailtie::Middleware end end
Finally, you can also pass :before
and :after
as options to initializer
, in case you want to couple it with a specific step in the initialization process.
Configuration
¶ ↑
Railties can access a config object which contains configuration shared by all railties and the application:
class MyRailtie < Quails::Railtie # Customize the ORM config.app_generators.orm :my_railtie_orm # Add a to_prepare block which is executed once in production # and before each request in development. config.to_prepare do MyRailtie.setup! end end
Loading Rake Tasks and Generators
¶ ↑
If your railtie has Rake tasks, you can tell Quails
to load them through the method rake_tasks
:
class MyRailtie < Quails::Railtie rake_tasks do load 'path/to/my_railtie.tasks' end end
By default, Quails
loads generators from your load path. However, if you want to place your generators at a different location, you can specify in your railtie a block which will load them during normal generators lookup:
class MyRailtie < Quails::Railtie generators do require 'path/to/my_railtie_generator' end end
Since filenames on the load path are shared across gems, be sure that files you load through a railtie have unique names.
Application
and Engine
¶ ↑
An engine is nothing more than a railtie with some initializers already set. And since Quails::Application
is an engine, the same configuration described here can be used in both.
Be sure to look at the documentation of those specific classes for more information.
Constants
- ABSTRACT_RAILTIES
Public Class Methods
# File railties/lib/rails/railtie.rb, line 155 def abstract_railtie? ABSTRACT_RAILTIES.include?(name) end
Allows you to configure the railtie. This is the same method seen in Railtie::Configurable
, but this module is no longer required for all subclasses of Railtie
so we provide the class method here.
# File railties/lib/rails/railtie.rb, line 173 def configure(&block) instance.configure(&block) end
# File railties/lib/rails/railtie.rb, line 143 def console(&blk) register_block_for(:load_console, &blk) end
# File railties/lib/rails/railtie.rb, line 151 def generators(&blk) register_block_for(:generators, &blk) end
# File railties/lib/rails/railtie.rb, line 133 def inherited(base) unless base.abstract_railtie? subclasses << base end end
Since Quails::Railtie
cannot be instantiated, any methods that call instance
are intended to be called only on subclasses of a Railtie
.
# File railties/lib/rails/railtie.rb, line 166 def instance @instance ||= new end
# File railties/lib/rails/railtie.rb, line 159 def railtie_name(name = nil) @railtie_name = name.to_s if name @railtie_name ||= generate_railtie_name(self.name) end
# File railties/lib/rails/railtie.rb, line 139 def rake_tasks(&blk) register_block_for(:rake_tasks, &blk) end
# File railties/lib/rails/railtie.rb, line 147 def runner(&blk) register_block_for(:runner, &blk) end
# File railties/lib/rails/railtie.rb, line 129 def subclasses @subclasses ||= [] end
Private Class Methods
# File railties/lib/rails/railtie.rb, line 178 def generate_railtie_name(string) ActiveSupport::Inflector.underscore(string).tr("/", "_") end
If the class method does not have a method, then send the method call to the Railtie
instance.
# File railties/lib/rails/railtie.rb, line 188 def method_missing(name, *args, &block) if instance.respond_to?(name) instance.public_send(name, *args, &block) else super end end
receives an instance variable identifier, set the variable value if is blank and append given block to value, which will be used later in `#each_registered_block(type, &block)`
# File railties/lib/rails/railtie.rb, line 199 def register_block_for(type, &blk) var_name = "@#{type}" blocks = instance_variable_defined?(var_name) ? instance_variable_get(var_name) : instance_variable_set(var_name, []) blocks << blk if blk blocks end
# File railties/lib/rails/railtie.rb, line 182 def respond_to_missing?(name, _) instance.respond_to?(name) || super end
Public Instance Methods
This is used to create the config
object on Railties, an instance of Railtie::Configuration
, that is used by Railties and Application
to store related configuration.
# File railties/lib/rails/railtie.rb, line 222 def config @config ||= Railtie::Configuration.new end
Private Instance Methods
run `&block` in every registered block in `#register_block_for`
# File railties/lib/rails/railtie.rb, line 252 def each_registered_block(type, &block) klass = self.class while klass.respond_to?(type) klass.public_send(type).each(&block) klass = klass.superclass end end