如何使用流利的api在EF中设置外键6

Question

在EF 6中，如何指定实体的属性是外键引用，以便在被引用的实体是父对象时不能删除另一个实体？

这是我的类：

public class User 
{ 
    [Key] 
    public int id { get; set; } 
    public int parentId { get; set; } 
    [ForeignKey("parentId")] 
    public virtual User user { get; set; } 
} 

在上述类中，parentId是到另一个User的引用。

这里是我当前的代码：

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    modelBuilder.Entity<User>().HasKey(x => x.id); 
    modelBuilder.Entity<User>().HasOptional<User>(x => x.user); 
    base.OnModelCreating(modelBuilder); 
} 

我收到以下错误：

One or more validation errors were detected during model generation:

DataService.Context.User_user: : Multiplicity conflicts with the referential constraint in Role 'User_user_Target' in relationship 'User_user'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'.

Answer 1

马培德的导航属性，你应该比添加地图类型用户的虚拟财产：

public class User 
{ 
[Key] public int id { get; set; }  
public int UserId { get; set; } 
public virtual User User{get;set;} 
} 
// ... 
modelBuilder.Entity<User>().HasOptional<User>(x=> x.User); 

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