Rails 3中的多态关联

Question

I've Googled and searched the forums but can't seem to find an answer that fits my scenario.

Let's say have the following models:

class TextProblem < ActiveRecord::Base
   belongs_to :askable, :polymorphic => true
   ...
end

class MultipleChoice < ActiveRecord::Base
   belongs_to :askable, :polymorphic => true
   ...
end

class WordMatch < ActiveRecord::Base
  belongs_to :askable, :polymorphic => true
  ...
end

Now I have another model called question. It has a field named question_type_id that indicates what type of question it is and a field named question_id that is the foreign key to one of the askables.. I want to do something like this:

class Question < ActiveRecord::Base
    has_one :askable, :foreign_key => 'question_id' ....  
end

and give it the correct askable but I'm not sure how to write the association. Am I looking at this right or should I be trying to achieve this another way?

Any help is appreciated!

Answer 1

You should have your association the other way round

class Question < ActiveRecord::Base
    belongs_to :askable, :polymorphic => true 
end

class TextProblem < ActiveRecord::Base
   has_many :questions, :as => :askable
   ...
end

class MultipleChoice < ActiveRecord::Base
   has_many :questions, :as => :askable
   ...
end

class WordMatch < ActiveRecord::Base
 has_many :questions, :as => :askable
  ...
end

Refer to this .