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module ActionController #:nodoc:
module Dependencies #:nodoc:
def self.append_features(base)
super
base.extend(ClassMethods)
end
# Dependencies control what classes are needed for the controller to run its course. This is an alternative to doing explicit
# +require+ statements that bring a number of benefits. It's more succinct, communicates what type of dependency we're talking about,
# can trigger special behavior (as in the case of +observer+), and enables Rails to be clever about reloading in cached environments
# like FCGI. Example:
#
# class ApplicationController < ActionController::Base
# model :account, :company, :person, :project, :category
# helper :access_control
# service :notifications, :billings
# observer :project_change_observer
# end
#
# Please note that a controller like ApplicationController will automatically attempt to require_dependency on a model of its
# singuralized name and a helper of its name. If nothing is found, no error is raised. This is especially useful for concrete
# controllers like PostController:
#
# class PostController < ApplicationController
# # model :post (already required)
# # helper :post (already required)
# end
#
# Also note, that if the models follow the pattern of just 1 class per file in the form of MyClass => my_class.rb, then these
# classes don't have to be required as Active Support will auto-require them.
module ClassMethods
# Specifies a variable number of models that this controller depends on. Models are normally Active Record classes or a similar
# backend for modelling entity classes.
def model(*models)
require_dependencies(:model, models)
depend_on(:model, models)
end
# Specifies a variable number of services that this controller depends on. Services are normally singletons or factories, like
# Action Mailer service or a Payment Gateway service.
def service(*services)
require_dependencies(:service, services)
depend_on(:service, services)
end
# Specifies a variable number of observers that are to govern when this controller is handling actions. The observers will
# automatically have .instance called on them to make them active on assignment.
def observer(*observers)
require_dependencies(:observer, observers)
depend_on(:observer, observers)
instantiate_observers(observers)
end
# Returns an array of symbols that specify the dependencies on a given layer. For the example at the top, calling
# <tt>ApplicationController.dependencies_on(:model)</tt> would return <tt>[:account, :company, :person, :project, :category]</tt>
def dependencies_on(layer)
read_inheritable_attribute("#{layer}_dependencies")
end
def depend_on(layer, dependencies) #:nodoc:
write_inheritable_array("#{layer}_dependencies", dependencies)
end
private
def instantiate_observers(observers)
observers.flatten.each { |observer| Object.const_get(Inflector.classify(observer.to_s)).instance }
end
def require_dependencies(layer, dependencies)
dependencies.flatten.each do |dependency|
begin
require_dependency(dependency.to_s)
rescue LoadError => e
raise LoadError.new("Missing #{layer} #{dependency}.rb").copy_blame!(e)
rescue Object => exception
exception.blame_file! "=> #{layer} #{dependency}.rb"
raise
end
end
end
end
end
end
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