您可以在实体框架中的自引用实体中定制外键名称吗？ [英] Can you customise foreign key names in self referencing entities in entity framework?

问题描述

我的应用程序中的一些实体具有4个审计属性：

  public virtual DateTime WhenAdded {get;组; } 
 
 public virtual DateTime？ WhenUpdated {get;组; } 
 
 public virtual User AddedBy {get;组; } 
 
 public virtual User UpdatedBy {get;组; } 
  

我正在使用代码第一种方法，并具有以下扩展方法来映射用户属性： / p>

  public static void MapAuditFields< T>（此EntityTypeConfiguration&T;配置）其中T：class，IAuditable 
 {
 configuration.HasOptional< User>（e => e.AddedBy）
 .WithOptionalDependent（）
 .Map（a => a.MapKey（AddedByUserId））; 
 configuration.HasOptional< User>（e => e.UpdatedBy）
 .WithOptionalDependent（）
 .Map（a => a.MapKey（UpdatedByUserId））; 
} 
  

这在大多数情况下都工作正常，但不在User类上，当然与本身有递归关系。我已经看到互联网上的各种帖子，建议实体框架在这种情况下尝试自定义连接表列名称时出现错误，例如：

首先引用多对多递归关系代码实体框架

和

http://social.msdn.microsoft.com/Forums/en-US/f058097d-a0e7-4393-98ef-3b13ab5b165d/code-first-sequence-contains-more-than-one-matching-element -exception-when-generate-schema？forum = adonetefx

我得到的错误是Sequence包含多个匹配元素。

有人知道吗如果这已经在实体框架6中修复了？

非常感谢。

解决方案

使用 WithMany（）而不是 WithOptionalDependent（），因为用户可以添加或更新多个其他用户

类：

  public class User 
 {
 public int Id {get;组; } 
 public virtual User AddedBy {get;组; } 
 
 public virtual User UpdatedBy {get;组; 
} 
  

流利的API调用：

  modelBuilder.Entity< User>（）
 .HasOptional（u => u.AddedBy）
 .WithMany（）
 .Map （fkamc => fkamc.MapKey（AddedByUserId））; 
 
 modelBuilder.Entity< User>（）
 .HasOptional（u => u.UpdatedBy）
 .WithMany（）
 .Map（fkamc => fkamc.MapKey（UpdatedByUserId））; 
  

结果：

Some of the entities in my application have 4 audit properties on them:

    public virtual DateTime WhenAdded { get; set; }

    public virtual DateTime? WhenUpdated { get; set; }

    public virtual User AddedBy { get; set; }

    public virtual User UpdatedBy { get; set; }

I am using a code first approach and have the following extension method to map the user properties:

    public static void MapAuditFields<T>(this EntityTypeConfiguration<T> configuration) where T : class, IAuditable
    {
        configuration.HasOptional<User>(e => e.AddedBy)
            .WithOptionalDependent()
            .Map(a => a.MapKey("AddedByUserId"));
        configuration.HasOptional<User>(e => e.UpdatedBy)
            .WithOptionalDependent()
            .Map(a => a.MapKey("UpdatedByUserId"));
    }

This is working fine in most cases, but not on the User class, which of course has a recursive relationship with itself. I have seen various posts on the internet suggesting that entity framework has a bug when you try to customise join table column names in this scenario, for example:

Self-referencing many-to-many recursive relationship code first Entity Framework

and

http://social.msdn.microsoft.com/Forums/en-US/f058097d-a0e7-4393-98ef-3b13ab5b165d/code-first-sequence-contains-more-than-one-matching-element-exception-when-generating-schema?forum=adonetefx

The error I am getting is "Sequence contains more than one matching element".

Does anyone know if this has been fixed in entity framework 6?

Many thanks.

解决方案

Use WithMany() instead of WithOptionalDependent() as a user can add or update multiple other users

Class:

public class User
{
    public int Id { get; set; }
    public virtual User AddedBy { get; set; }

    public virtual User UpdatedBy { get; set; }
}

Fluent API calls:

        modelBuilder.Entity<User>()
            .HasOptional( u => u.AddedBy )
            .WithMany()
            .Map( fkamc => fkamc.MapKey( "AddedByUserId" ) );

        modelBuilder.Entity<User>()
            .HasOptional( u => u.UpdatedBy )
            .WithMany()
            .Map( fkamc => fkamc.MapKey( "UpdatedByUserId" ) );

Results:

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