設置一：的has_many：on Rails的通過一個belongs_to的關聯紅寶石協會

Question

我有三個型號，每個都具有以下關聯：

class Model1 < ActiveRecord::Base 
    has_many :model2s 
    has_many :model3s 
end 

class Model2 < ActiveRecord::Base 
    belongs_to :model1 
    has_many :model3s, :through => :model1 # will this work? is there any way around this? 
end 

class Model3 < ActiveRecord::Base 
    belongs_to :model1 
    has_many :model2s, :through => :model1 # will this work? is there any way around this? 
end 

正如你可以在註釋文本看，我剛纔提到我需要什麼。

Answer 1

你剛纔創建的方法來訪問它

class Model2 < ActiveRecord::Base 
    belongs_to :model1 

    def model3s 
    model1.model3s 
    end 
end 

或者，您也可以委託給MODEL1的model3s方法

class Model2 < ActiveRecord::Base 
    belongs_to :model1 

    delegate :model3s, :to => :model1 

end 

Answer 2

爲什麼不嘗試：

class Model1 < ActiveRecord::Base 
    has_many :model2s 
    has_many :model3s 
end 

class Model2 < ActiveRecord::Base 
belongs_to :model1 
has_many :model3s, :primary_key => :model1_id, 
         :foreign_key => :model1_id 

end 

class Model3 < ActiveRecord::Base 
    belongs_to :model1 
    has_many :model2s, :primary_key => :model1_id, 
         :foreign_key => :model1_id 
end 

這將有有效的記錄通過model1_id加入model2和model3，使model1完全脫離它並且應該更加高效。