[英]How to Create two Foreign Keys in one Table pointing to the same Column in some table?
[英]How to create 2 string foreign keys pointing at the same unique string column?
我有一個實體“ Player”,它具有字符串類型的“ Guid”屬性,具有唯一性約束。
我有一個“ PlayerData”實體,該實體具有字符串類型的“ PlayerGuid”,“ OpponentPlayerGuid”屬性。
如何使用EF Core確保PlayerGuid和OpponentPlayerGuid屬性接受僅在Player.Guid屬性中找到的值?
我已經嘗試了各種方法,從關於stackoverflow的5個以上不同的答案中,沒有一個能幫助我解決這個問題。
PlayerData實體
public class PlayerData
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public int AttackLevel { get; set; } = 0;
public int DefenseLevel { get; set; } = 0;
[InverseProperty("Guid")]
public string PlayerGuid { get; set; }
public Player Player { get; set; }
//[ForeignKey("OpponentPlayerGuid")]
//public string OpponentPlayerGuid { get; set; }
public int WinStreak { get; set; } = 0;
public double Armor { get; set; }
public double Health { get; set; }
public bool Acted { get; set; }
public ActionType LastAction { get; set; }
}
玩家實體
public class Player
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
[ForeignKey("SessionId")]
public int? SessionId { get; set; }
public Session Session { get; set; }
[Required,MaxLength(36)]
public string Guid { get; set; }
public DateTime? BanTime { get; set; }
public List<PlayerData> PlayerDatas { get; set; }
}
您需要在guid上指定Alternate鍵。 然后為其配置外鍵。 通過使用流暢的API來做到這一點。 此處的用法示例: https : //docs.microsoft.com/zh-CN/ef/core/modeling/alternate-keys 。
在您的DbContext類中:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<PlayerData>()
.HasOne(e => e.Player)
.WithMany() // If its a one to one relationsship, specify 'WithOne()' here
.HasForeignKey(e => e.PlayerGuid)
.OnDelete(DeleteBehavior.Restrict);
modelBuilder.Entity<PlayerData>()
.HasOne(e => e.OpponentPlayer)
.WithMany()
.HasForeignKey(e => e.OpponentPlayerGuid)
.OnDelete(DeleteBehavior.Restrict);
}
附帶說明:您應該使用BCL提供的值類型Guid
而不是字符串。 這樣,您的ID將永遠是Guid。
如果您不介意我問,是否有任何特定原因導致您不使用Id來引用Player和OpponentPlayer? 然后,您可以使用外鍵引用Player表。
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