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课程：

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; }
    }

最后两个虚拟属性问题。我打电话的时候：

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

我得到以下例外：

Invalid column name 'Following_UserId'.

问题可能是由于一个类中有两个User对象引起的。知道如何解决这个问题吗？
的更新

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无法将第一个属性识别为外键。您可以通过使用[ForeignKey]属性明确指定FK属性来解决问题：

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; }
}

修改

至少第二个属性不遵守命名约定，第一个属性看起来没问题。因此，您也可以通过将第二个FK属性FollowUserId重命名为：
来解决问题
public Guid FollowingUserId { get; set; }

...因为导航属性称为Following。

修改2

关于您的更新：您需要添加[InverseProperty]属性以告知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; } }

实体框架类中的两个相同的类类型问题

1 个答案: