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 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

abstract_railtie?() click to toggle source
# File railties/lib/rails/railtie.rb, line 155
def abstract_railtie?
  ABSTRACT_RAILTIES.include?(name)
end
configure(&block) click to toggle source

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
console(&blk) click to toggle source
# File railties/lib/rails/railtie.rb, line 143
def console(&blk)
  register_block_for(:load_console, &blk)
end
generators(&blk) click to toggle source
# File railties/lib/rails/railtie.rb, line 151
def generators(&blk)
  register_block_for(:generators, &blk)
end
inherited(base) click to toggle source
# File railties/lib/rails/railtie.rb, line 133
def inherited(base)
  unless base.abstract_railtie?
    subclasses << base
  end
end
instance() click to toggle source

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
railtie_name(name = nil) click to toggle source
# 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
rake_tasks(&blk) click to toggle source
# File railties/lib/rails/railtie.rb, line 139
def rake_tasks(&blk)
  register_block_for(:rake_tasks, &blk)
end
runner(&blk) click to toggle source
# File railties/lib/rails/railtie.rb, line 147
def runner(&blk)
  register_block_for(:runner, &blk)
end
subclasses() click to toggle source
# File railties/lib/rails/railtie.rb, line 129
def subclasses
  @subclasses ||= []
end

Private Class Methods

generate_railtie_name(string) click to toggle source
# File railties/lib/rails/railtie.rb, line 178
def generate_railtie_name(string)
  ActiveSupport::Inflector.underscore(string).tr("/", "_")
end
method_missing(name, *args, &block) click to toggle source

If the class method does not have a method, then send the method call to the Railtie instance.

Calls superclass method
# 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
register_block_for(type, &blk) click to toggle source

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
respond_to_missing?(name, _) click to toggle source
Calls superclass method
# File railties/lib/rails/railtie.rb, line 182
def respond_to_missing?(name, _)
  instance.respond_to?(name) || super
end

Public Instance Methods

config() click to toggle source

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

each_registered_block(type, &block) click to toggle source

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