Module: ActiveRecord::Concernable

Defined in:
lib/activerecord-concernable.rb

Instance Method Summary collapse

Instance Method Details

#concern(name, opts = {}, &block) ⇒ Object

Defines a concern.

Concern will be named by convention below the ::Concerns module. Concern will be wrapped in namespace named by convention from the class defining the concern. For example, a User concern within the Notification class would be available at ::Concerns::Notification::User

By convention, if a class is passed as the concern name, the concern will be automatically mixed into the passed class. If this functionality is not desirable, pass the name as a symbol i.e. :user.

To mix into additional classes, pass them classes as an array to the of option key.

Example:

class Notification
  extend Concernable

  concern :user do
    included do
      has_many :notifications
    end
  end

  concern :notifiable, of: [Comments, Posts] do
    include do
      has_many :notifications, as: :subject, dependent: :destroy
    end

    def create_notifcation(*args)
      notications.create(*args)
    end
  end
end



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# File 'lib/activerecord-concernable.rb', line 41

def concern(name, opts={}, &block)
  namespace = self.to_s.split('::').reduce(::Concerns) do |namespace, module_name|
    namespace.const_defined?(module_name, false) ? namespace.const_get(module_name) : namespace.const_set(module_name, Module.new)
  end

  # Create and populate concern module.
  camelized_name = name.to_s.camelize
  concern = Module.new
  concern.send(:extend, ActiveSupport::Concern)
  concern.class_eval(&block)
  concern = namespace.const_set(camelized_name, concern)

  # Mix-in concern
  opts.symbolize_keys!
  opts[:of] = Array(opts[:of])
  opts[:of] << name if name.instance_of? Class
  Array(opts[:of]).each { |klass| klass.send(:include, concern) }
end