流利的API，EF 4.1：继承和外键的问题

问题描述

有几个简单的类：

第一类：

  public class User 
 {
 public int UserId {get;组; } 
 public string Username {get;组; } 
 
 // ... 
 
 public ICollection<主题>主题{get;组; 
} 
  

第二类：

  public class Publication 
 {
 public int PublicationId {get;组; } 
 public string标题{get;组; } 
 
 / ... 
 
 public User Author {get;组; 
} 
  

第三类：

  public class主题：出版物
 {
 public string TopicContent {get;组; } 
 
 // ... 
} 
  

创建后一个我的模型的数据库我有以下数据库的结构：

用户

UserId

UserName

出版物

PublicationId

标题

主题内容

Author_UserId

User_UserId

正如你所看到的，我得到两个字段Author_UserId和User_UserId具有相同的

如何使用Fluent API或数据注释将此字段合并到一个字段？

解决方案

我不认为在出版物表中可以有相同的外键列。 Publication.Author 和 User.Topics 不能是同一个关联的端点。您可能有一个发布实例，它不是主题，并引用用户：

  User user = new User（）{Topics = new List< Topic>（） ; 
出版刊物= new Publication（）; 
 
 publication.Author = user; 
 
 user.Topics.Add（???）; 
  

在???您不能添加发布，因为它不是主题实例。 user.Topics 必须引用另一个对象，而不是 publication ，这意味着这些端点不能属于同一个关联。 p>

修改

如果您只想要一个关联，只有一个外键列在数据库中，您必须将作者属性从出版物移动到主题或让您的用户类中的集合引用发布而不是主题：

  public ICollection< Publication>出版物{get;组; } 
  

There are several simple classes:

The first class:

public class User
{
   public int UserId { get; set; }
   public string Username { get; set; }

   // ...

   public ICollection<Topic> Topics { get; set; }
}

The second class:

public class Publication
{
   public int PublicationId { get; set; }
   public string Title { get; set; }

   / ...

   public User Author { get; set; }
}

The third class:

public class Topic: Publication
{
   public string TopicContent { get; set; }

   // ...
}

After creating a database for my model I have the following stucture of the database:

Users

UserId

UserName

Publications

PublicationId

Title

TopicContent

Author_UserId

User_UserId

As you can see I get two fields Author_UserId and User_UserId having identical role in the table Publications.

How can I merge this fields into one field using Fluent API or Data Annotation?

解决方案

I don't think that it's possible to have the same foreign key column in the Publications table. Publication.Author and User.Topics cannot be the endpoints of one and the same association. You could have a Publication instance which isn't a Topic and a reference to a User:

User user = new User() { Topics = new List<Topic>() };
Publication publication = new Publication();

publication.Author = user;

user.Topics.Add(???);

At ??? you can't add publication because it isn't a Topic instance. user.Topics must refer to another object than publication which means that those endpoints cannot belong to the same association.

Edit

If you want only one single association with only a single foreign key column in the database you must either move the Author property from Publication to Topic or let the collection in your User class refer to Publication instead of Topic:

public ICollection<Publication> Publications { get; set; }

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