有关空的belongs_to关联的最佳实践 [英] Best practice about empty belongs_to association

问题描述

想象一下以下情况：

我有一个狗模型和一个房子模型。狗可以属于一个房子，而一个房子可以有很多狗，因此：

I have a dog model and a house model. A dog can belong to a house, and a house can have many dogs, so:

Class Dog <  ActiveRecord::Base
  belongs_to :house
end

Class House < ActiveRecord::Base
  has_many :dogs
end

现在，想象一下我也想创造没有房子的狗。他们不属于房屋。我仍然可以使用这种关系结构，而在创建它时不通知：house_id 吗？

Now, imagine that I also want to create dogs that don't have a house. They don't belong to house. Can I still use that relationship structure and simply don't inform a :house_id when creating it?

更好的做法？

Obs .：我用这种类比简化了我的问题，但是我的实际情况是：我有一个模型，用户可以生成它的实例。他还可以创建这些实例的集合，但可以将实例留在集合之外。

Obs.: I used this analogy to simplify my problem, but my real situation is: I have a model a user can generate instances of it. He can also create collections of those instances, but he can leave an instance outside a collection.

推荐答案

我认为这是绝对正常的方法。

I think it is absolutely normal approach.

您只需在 null 值中保留 house_id 不属于其他模型的数据库。

You can just leave house_id with null value in database for the models which don't belong to other.

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