如何首先在Entity Framework 4代码中映射复合主键？ [英] How do I map a composite primary key in Entity Framework 4 code first?

问题描述

我首先要掌握EF4代码，并且很喜欢它。但是我无法将实体映射到具有复合主键的表。

我尝试的配置如下所示：

  public SubscriptionUserConfiguration（）
 
 {
属性（u => u.SubscriptionID）.IsIdentity（）; 
属性（u => u.UserName）.IsIdentity（）; 
} 
  

哪个抛出这个异常：
无法推断实体的键

解决方案

你也可以使用

  HasKey（u => new {u.SubscriptionID，u.UserName}）; 
  

编辑：

发现以下情况不起作用：

  public ProjectAssignmentConfiguration（）
 {
 HasKey（u = > u.Employee.EmployeeId）; 
 HasKey（u => u.Project.ProjectId）; 
} 
  

或

  public ProjectAssignmentConfiguration（）
 {
 HasKey（u => new {u.Employee.EmployeeId，u.Project.ProjectId}）; 
} 
  

那么如何设置连接表有一个主键的实体由外键组成？

I'm getting to grips with EF4 code first, and liking it so far. But I'm having trouble mapping an entity to a table with a composite primary key.

The configuration I've tried looks like this:

public SubscriptionUserConfiguration()

    {
                Property(u => u.SubscriptionID).IsIdentity();
                Property(u => u.UserName).IsIdentity();
    }

Which throws this exception: Unable to infer a key for entity type 'SubscriptionUser'.

What am I missing?

解决方案

You could also use

HasKey(u => new { u.SubscriptionID, u.UserName });

Edit:

One limitation I have found is that the following do not work:

public ProjectAssignmentConfiguration()
{
    HasKey(u => u.Employee.EmployeeId);
    HasKey(u => u.Project.ProjectId);
}

or

public ProjectAssignmentConfiguration()
{
    HasKey(u => new { u.Employee.EmployeeId, u.Project.ProjectId });
}

So how do you set up an entity where the join table has a primary key that is composed of foreign keys?

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