Question

我在使用EF代码优先创建数据库时遇到问题。我有一个实体玩家和一个实体炸船。

每个友谊都会引用两名球员。其中一个是发件人，另一个是友谊的接收者。

这是我的实体：

Player.cs

public class Player
{
    public int PlayerId { get; set; }

    [Required]
    public string Name { get; set; }

    [Required]
    public string Email { get; set; }

    [InverseProperty("Receiver")]
    public virtual List<Friendship> FriendshipsIncoming { get; set; }

    [InverseProperty("Sender")]
    public virtual List<Friendship> FriendshipsOutgoing { get; set; }
}

Friendship.cs

public class Friendship
{
    public int FriendshipId { get; set; }

    public int SenderId { get; set; }
    public int ReceiverId { get; set; }

    [ForeignKey("Sender")]
    public Player Sender { get; set; }

    [ForeignKey("Receiver")]
    public Player Receiver { get; set; }

    [Required]
    public bool Confirmed { get; set; }
}

我尝试按照本教程中显示的方式实现关系： http://www.entityframeworktutorial.net/code-first/inverseproperty-dataannotations-attribute-in-code-first.aspx

尝试使用＆＃34; update-database＆＃34;更新数据库时命令我收到以下错误消息：

属性＆＃39; Receiver＆＃39;上的ForeignKeyAttribute在类型＆＃39; Darta.WebApi.Models.Friendship＆＃39;无效。外键名称＆＃39; Receiver＆＃39;在依赖类型＆＃39; Darta.WebApi.Models.Friendship＆＃39;中找不到。 Name值应该是以逗号分隔的外键属性名称列表。

我也尝试使用如下所示的fluent-api解决问题： http://csharpwavenet.blogspot.sg/2013/06/multiple-foreign-keys-with-same-table.html

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Friendship>()
            .HasRequired(b => b.Sender)
            .WithMany(a => a.FriendshipsOutgoing)
            .HasForeignKey(b=>b.SenderId);

        modelBuilder.Entity<Friendship>()
            .HasRequired(b => b.Receiver)
            .WithMany(a => a.FriendshipsIncoming)
            .HasForeignKey(b => b.ReceiverId);
    }

在这种情况下，我收到以下错误：

介绍FOREIGN KEY约束＆＃39; FK_dbo.Friendships_dbo.Players_SenderId＆＃39;在桌上＆＃39;友谊＆＃39;可能会导致循环或多个级联路径。指定ON DELETE NO ACTION或ON UPDATE NO ACTION，或修改其他FOREIGN KEY约束。无法创建约束或索引。查看以前的错误。

Answer 1

您应该只需要数据注释或 FluentAPI。你不需要两者兼而有之。如果您想使用[ForeignKey]和[InverseProperty]属性，请删除FluentAPI代码。

另请注意，在[ForeignKey]和[InverseProperty]属性中，您需要指定列的名称，而不是导航属性。

public class Player
{
    public int PlayerId { get; set; }

    [Required]
    public string Name { get; set; }

    [Required]
    public string Email { get; set; }

    [InverseProperty("ReceiverId")]
    public virtual ICollection<Friendship> FriendshipsIncoming { get; set; }

    [InverseProperty("SenderId")]
    public virtual ICollection<Friendship> FriendshipsOutgoing { get; set; }
}

public class Friendship
{
    public int FriendshipId { get; set; }

    public int SenderId { get; set; }
    public int ReceiverId { get; set; }

    [ForeignKey("SenderId")]
    public Player Sender { get; set; }

    [ForeignKey("ReceiverId")]
    public Player Receiver { get; set; }

    [Required]
    public bool Confirmed { get; set; }
}

Answer 2

我会纠正答案。 InverseProperty必须是有效的实体类型。所以在这种情况下，Friendship.Receiver，Friendship.Sender

公共类播放器 { public int PlayerId {get;组; }

   [Required]
   public string Name { get; set; }

   [Required]
   public string Email { get; set; }

   [InverseProperty("Receiver")]
   public virtual ICollection<Friendship> FriendshipsIncoming { get; set; }

   [InverseProperty("Sender")]
   public virtual ICollection<Friendship> FriendshipsOutgoing { get; set; }

}

公共课友谊 { public int FriendshipId {get;组; }

   public int SenderId { get; set; }
   public int ReceiverId { get; set; }

   [ForeignKey("SenderId")]
   public Player Sender { get; set; }

   [ForeignKey("ReceiverId")]
   public Player Receiver { get; set; }

   [Required]
   public bool Confirmed { get; set; }

}

实体框架对同一个表

2 个答案: