实体框架类问题中的两个相同的类类型

Question

我正在实现允许用户互相关注的功能。 我有数据库表：

User{UserId, FirstName, LastName etc.}
Followings{FollowerUserId, FollowingUserId, CreatedOnDate etc.}

所以我添加了 EF 类：

public class Follow
    {
        [Key, Column(Order = 1)]
        public Guid FollowerUserId { get; set; }
        [Key, Column(Order = 2)]
        public Guid FollowUserId { get; set; }        
        public DateTime CreatedOnDate { get; set; }

        public virtual User Follower { get; set; }
        public virtual User Following { get; set; }
    }

最后两个虚拟属性会导致问题。 当我打电话时：

var model = con.Follows.Where(x => x.FollowerUserId == uid);

我得到以下异常：

Invalid column name 'Following_UserId'.

这个问题可能是因为一个类中有两个 User 对象。知道如何解决这个问题吗？
更新

public class User
    {

        public Guid UserId { get; set; }
        ...
        public virtual ICollection<Follow> Following { get; set; }
        public virtual ICollection<Follow> Followers { get; set; }
    }

Answer 1

我认为原因是外键属性（FollowerUserId 和 FollowUserId）和导航属性（Follower 和 Following）不遵守命名约定，因此 EF 无法识别第一个属性作为外键。您可以通过使用 [ForeignKey] 属性显式指定 FK 属性来解决此问题：

public class Follow
{
    [Key, Column(Order = 1), ForeignKey("Follower")]
    public Guid FollowerUserId { get; set; }
    [Key, Column(Order = 2), ForeignKey("Following")]
    public Guid FollowUserId { get; set; }        

    public DateTime CreatedOnDate { get; set; }

    public virtual User Follower { get; set; }
    public virtual User Following { get; set; }
}

编辑

至少第二个属性不遵守命名约定，第一个看起来不错。因此，或者您可以通过将第二个 FK 属性 FollowUserId 重命名为：

public Guid FollowingUserId { get; set; }        

...因为导航属性被称为Following。

编辑 2

关于您的更新：您需要添加 [InverseProperty] 属性来告诉 EF 哪些导航属性属于一起：

public class Follow
{
    [Key, Column(Order = 1), ForeignKey("Follower")]
    public Guid FollowerUserId { get; set; }
    [Key, Column(Order = 2), ForeignKey("Following")]
    public Guid FollowUserId { get; set; }        

    public DateTime CreatedOnDate { get; set; }

    [InverseProperty("Followers")]  // refers to Followers in class User
    public virtual User Follower { get; set; }
    [InverseProperty("Following")]  // refers to Following in class User
    public virtual User Following { get; set; }
}