将属性添加到多对多关系? [英] Adding properties to many to many relationship?

问题描述

我一直在使用Core Data对数据库进行建模.我有2个处于多对多关系的实体.每个人可以有多个地址，并且每个人可以居住在每个地址上.

I have been using Core Data to model my database. I have 2 entities that are in many to many relationship. Each person can have many addresses, and on each address multiple persons can live.

现在，我想向此关系添加属性.例如，一个人-地址将带有标签家，其他人-地址将具有标签妈妈的位置.

Now i would like to add property to this relationship. For example one person - address will have label home, other person - address can will have label mama's place.

我不能在地址实体上添加此属性，因为相同的地址将为不同的人提供不同的标签.

I can't add this property on address entity, because same address will have different labels for different persons.

由于关系的建模方式类似于NSSet，因此我看不到有一种做我想做的事的方法.

Since relationships are modeled like NSSets, I don't see a way to do what I want.

这可以通过某种方式完成吗?

Can this be somehow done?

推荐答案

不可能直接将属性添加到多对多关系中.苹果公司推荐的方法(请参见基于关系建模"(《 CoreData编程指南》中的"")中，将中间关系实体替换为多对多关系，并在中间实体中添加了属性.您现有的每个实体都将与新实体建立一对多的关系.

It is not possible to add attributes to a many-many relationship directly. The Apple-recommended approach (see "Modelling a relationship based on its semantics" in the CoreData Programming Guide) is to replace the many-many relationship with an intermediate entity, to which you add the attributes. Each of your existing entities will have a one-many relationship with the new entity.

在您的情况下，您可能会遇到类似这样的情况:

In your case, you might have something like this:

Person     <--->> PersonAddressDetails <<--->    Address

然后可以将label属性添加到PersonAddressDetails实体.

You can then add the label attribute to the PersonAddressDetails entity.

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