Question

I have a users_manager engine which has a User model class.

In an other shopping engine, I add some associations in the User model with the code below, in shopping/lib/shopping.rb:

module Shopping
  class Engine<Rails::Engine
    initializer :shopping_append_user do
       UsersManager::User.class_eval do
        has_many :products,:class_name=>"Shopping::Product"
        has_many :virtues,:class_name=>"Shopping::Virtue"
        has_many :containers,:class_name=>"Shopping::Container"
        has_many :concerns,:class_name=>"Shopping::Concern"
        has_many :remarks,:class_name=>"Shopping::Remark"
        has_many :praisings,:class_name=>"Shopping::Praising"
        has_one  :cart,:class_name=>"Shopping::Cart"
        has_one  :shop_information,:class_name=>"Shopping::ShopInformation"
        has_many :comments,:class_name=>"Shopping::Comment"
        has_many :created_orders,:class_name=>"Shopping::Order",:foreign_key=>"creator_id"
        has_many :processing_orders,:class_name=>"Shopping::Order",:foreign_key=>"processor_id"
      end
    end

    initializer :shopping_append_file do
      Upload::File.class_eval do
        has_many :image_uuids,:class_name=>"Shopping::ImageUuid"
      end
    end
  end

  def self.table_name_prefix
    "shopping_"
  end
end

After running rails server, the application works fine. However, after modifying one controller file, I browse the web page and it gives me the following message :

undefined method `products' for #<UsersManager::User:0x00000003022a58>

How does rails reload the file after modifying them? How can I make my engine work right?

My version of rails is 3.2.0.pre from github, Ruby is 1.9.0.

Answer 1

Your initializer isn’t reloaded on every request, this means that your customizations on the UsersManager::User class are lost when it is reloaded.

You can do the following instead:

module Shopping
  class Engine < Rails::Engine
    config.to_prepare do
      Shopping.customize_user
      Shopping.customize_file
    end
  end

  def self.customize_user
     UsersManager::User.class_eval do
      has_many :products,:class_name=>"Shopping::Product"
      has_many :virtues,:class_name=>"Shopping::Virtue"
      has_many :containers,:class_name=>"Shopping::Container"
      has_many :concerns,:class_name=>"Shopping::Concern"
      has_many :remarks,:class_name=>"Shopping::Remark"
      has_many :praisings,:class_name=>"Shopping::Praising"
      has_one  :cart,:class_name=>"Shopping::Cart"
      has_one  :shop_information,:class_name=>"Shopping::ShopInformation"
      has_many :comments,:class_name=>"Shopping::Comment"
      has_many :created_orders,:class_name=>"Shopping::Order",:foreign_key=>"creator_id"
      has_many :processing_orders,:class_name=>"Shopping::Order",:foreign_key=>"processor_id"
    end
  end

  def self.customize_file
    Upload::File.class_eval do
      has_many :image_uuids,:class_name=>"Shopping::ImageUuid"
    end
  end

  def self.table_name_prefix
    "shopping_"
  end
end

The config.to_prepare block is run once in production and before every request in development (source).