防止Rails3中模型（只希望允許創建從另一個模型中）

Question

我想確保

MyModel.new # ...raises an error... 

和

MyOtherModel::create_my_model # ...only this should work! 

什麼是好辦法做這個？

謝謝。

Answer 1

沒有直接AFAIK。以下應該工作。

class MyModel < ActiveRecord::Base 
    .. 
    belongs_to :my_other_model 
    def initialize(need_this_argument = nil) 
    raise if need_this_argument.nil? 
    super() # It is important to put the() here. 
    end 
end 

class MyOtherModel < ActiveRecord::Base 
... 
    has_one :my_model 
    accepts_nested_attributes_for :my_model 
    def create_my_model(arguments) 
    MyModel.new(true) # Pass a non nil argument 
    end 
end 

MyModel.new＃=> RuntimeError
A = MyOtherModel.new
B = a.create_my_model
..＃做你的東西在這裏
b.save
a.save