EF Core 1.0外鍵問題

Question

我真的不明白這是EF Core 1.0錯誤嗎？

public class User : BaseEntity
{
    public string Username { get; set; }
}
public class UserDetail : BaseEntity
{
    public int UserId { get; set; }
    public string Address { get; set; }
    public string Country { get; set; }

    public virtual User User { get; set; }

    [ForeignKey("UserId")]
    public virtual ICollection<UserLanguage> Languages { get; set; }
}

public class UserLanguage : BaseEntity
{
    public string Name { get; set; }
    public int UserId { get; set; }
}

在我的用戶表中，我有3個用戶

Id          Username
----------- ---------------

1           john
2           doe
3           jack

在我的UserDetail中，我有2條記錄

Id          UserId      Address                                           Country
----------- ----------- -------------------------------------------------- ------
1           1           Some Address                                       MY
2           3           NULL                                               SG

在我的UserLanguage中執行插入時

INSERT INTO UserLanguage(Name, UserId)
VALUES ('English', 3) 

它將遇到以下錯誤

The INSERT statement conflicted with the FOREIGN KEY constraint "FK_UserLanguage_UserDetail_UserId". The conflict occurred in database "Job", table "dbo.UserDetail", column 'Id'.

我在這里做錯了什么？ ForeignKey是UserId，它如何指向UserDetail列“ Id”

Answer 1

嘗試以下

public class User : BaseEntity
{
    public string Username { get; set; }

    public virtual ICollection<UserLanguage> Languages { get; set; }
}
public class UserDetail : BaseEntity
{
    public int UserId { get; set; }
    public string Address { get; set; }
    public string Country { get; set; }

    public virtual User User { get; set; }        
}

public class UserLanguage : BaseEntity
{
    public string Name { get; set; }
    public int UserId { get; set; }

    public virtual User User { get; set; } 
}

問題出在下面的代碼行中

[ForeignKey("UserId")]
public virtual ICollection<UserLanguage> Languages { get; set; }

這將在UserDetail和UserLanguage表之間創建外鍵關系，而您想在User和UserLanguage表之間創建外鍵關系。

在現有架構中，如果您嘗試插入

INSERT INTO UserLanguage(Name, UserId)
VALUES ('English', 1) 
INSERT INTO UserLanguage(Name, UserId)
VALUES ('French', 2) 

由於UserDetail有兩個帶有1,2 PK的條目，而UserDetail中沒有帶有PK 3的條目，它將成功。

Answer 2

在您的UserLanguage類中嘗試添加：

public virtual UserDetail UserDetail  { get; set; }