如何使用模型优先方法在 EF4 中创建 1x0..1 关联？

发布于 2024-11-01 14:59:19 字数 1268 浏览 0 评论 0原文

考虑以下示例模型：

Person has 0..1 User
User has 1 Person

Attempt 1:

我从 Person 中拖动了一个关联 到模型设计器上的User。
我修复了基数以满足我的需求（默认为 1xN）
我从模型生成了 DDL

问题：

输出 User 表有一个 Person_id没有唯一约束的列。也就是说，它不是 1x1 关系，因为许多用户可以引用同一个人。这里一定有问题

尝试2：

在模型设计器上将关联从“Person”拖到“User”。
修复了基数以满足我的需求（默认为 1xN）
选择关联并单击属性窗口上的Referential Constraint按钮来编辑关联
Selected Person to be the Primary and User to be Dependent type
选择Principal Key作为Id，Dependent Property也作为Id（我在某处读过，我应该对这两种类型使用相同的密钥）

问题：

我运行此代码：

using (var context = new Locadora())
{
    User user = new User ();
    user.PasswordHash = "hash";
    user.Pessoa = new Person();
    user.Pessoa.Nome = "André";

    context.Usuários.AddObject(user);

    context.SaveChanges();
}

SaveChanges 触发此异常：

ReferentialConstraint 中的依赖属性映射到存储生成的列。列：“ID”

所以我现在别无选择。我不知道如何在实体框架中实现 1x1 和 1x0..1 关系。

我该怎么做？

原文

Consider the following example model:

Person has 0..1 User
User has 1 Person

Attempt 1:

I dragged an association from Person to User on the model designer.
I fixed the cardinality to meet my needs (the default is 1xN)
I generated the DDL from model

Problem:

The output User table has a Person_id column with no unique constraint. That is, it's not a 1x1 relationship as many Users can reference the same Person. There must be something wrong here

Attempt 2:

Dragged an association from Person to User on the model designer.
Fixed the cardinality to meet my needs (the default is 1xN)
Selected the association and clicked the Referential Constraint button on the properties window to edit the association
Selected Person to be the Principal and User to be the Dependent type
Chosen the Principal Key to be Id and the Dependent Property to be also Id (I've read somewhere that I should use the same key for both types)

Problem:

I run this code:

using (var context = new Locadora())
{
    User user = new User ();
    user.PasswordHash = "hash";
    user.Pessoa = new Person();
    user.Pessoa.Nome = "André";

    context.Usuários.AddObject(user);

    context.SaveChanges();
}