多态与has_one，belongs_to的区别

Question

We have model called as Human having following column, name, password and behavior. we have another three models namely admins, receivers, donors whose fields varies according to the human behavior. Now I want to know whether I should use polymorphic associations or has_one belongs_to association?

Answer 1

Your questions was a little unclear, but here's a general guide:

1) If it belongs to multiple other models, it should be polymorphic.

2) If it only belongs to only one other model, it should belong_to that other model.

3) If you're unsure of the future structure of your associations, polymorphic is a great bet because it can fit almost any structure, and it's fairly easy to undo.

Let me know if you need any clarification.

Answer 2

Before answering this question we need to understand the polymorphic associations and has_one belongs_to associations first,

Polymorphic association: When we need to build association where a model is associated with more than one models we need to go for polymorphic. quoting example from rails guide.

    class Picture < ActiveRecord::Base
      belongs_to :imageable, polymorphic: true
    end

    class Employee < ActiveRecord::Base
      has_many :pictures, as: :imageable
    end

    class Product < ActiveRecord::Base
      has_many :pictures, as: :imageable
    end

Whereas when we have just one to one relationship between models and there is no association which associate from one model to second model and again some relation between first and third model then we can go for belongs_to and has_many associations. Hope this clarify. let me know if more clarification needed.

More Here