Ruby on Rails多态关联-案例

Question

How would you represent the following case in terms of Ruby-on-Rails associations?

Content (name, description, link)

has one/belongs to one or more

Author

which is one of these three types:

Person (first_name, surname) OR Artist (artist_name) OR Duo (name1, name2)

Answer 1

When I was learning about polymorphic-associations there where 2 sources that really help me

1. guides.rubyonrails.org polymorphic-associations
2. railscasts 1polymorphic-association

you have to remember that you have a model that will connect with others so you need to have a key value to know to what model and row to connect

class Content < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
end

class Person < ActiveRecord::Base
  has_many :contents, as: :commentable
end

class Artist < ActiveRecord::Base
  has_many :contents, as: :commentable
end

note that in your Content model you should add commentable_id (as a integer key of the field you are connection to)

commentable_type (as a string, this is going to be the model name that you are connecting to)

Content (name, description, link, commentable_id, commentable_type)