INSERT語句與FOREGIGN KEY約束衝突

Question

我是一名綠色的asp.net開發人員，我正在使用最新的實體框架與我的項目。我遇到了一個問題，我的數據庫採用自動生成的值（我認爲）。這是確切的錯誤。

下面的代碼：

public class Address 
{ 
     [Key] 
     [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
     public int AddressId { get; set; } 
// some more properties 
} 

public class ApplicationUser : IdentityUser 
{ 
     [ForeignKey("Address")]   
    public int AddressId { get; set; } 
    public Address Address { get; set; } 

// some more properties 
} 

public class Shelter 
{ 
     [Required] 
     [ForeignKey("Address")] 
     public int AddressId { get; set; } 
     public Address Address { get; set; } 
// some more properties 
} 
//seed 
private void CreateShelters() 
{ 
    EntityEntry<Address> MspcaAddress = DbContext.Addresses.Add(new Address() 
    { 
       Street = "350 S Huntington Ave", 
       City = "Jamaica Plain", 
       State = "MA", 
       AreaCode = "02130", 
       Latitude = 42.3228928, 
       Longititude = -71.11120540000002 
    }); 
    EntityEntry<Address> BostonAnimalCareAndControlAddress = DbContext.Addresses.Add(new Address() 
    { 
       Street = "26 Mahler Rd", 
       City = "Roslindale", 
       State = "MA", 
       AreaCode = "02131", 
       Latitude = 42.2943377, 
       Longititude = -71.12153390000003 
      }); 
      EntityEntry<Address> AnimalRescueLeagueOfBostonAddress = DbContext.Addresses.Add(new Address() 
      { 
       Street = "10 Chandler St", 
       City = "Boston", 
       State = "MA", 
       AreaCode = "0S2116", 
       Latitude = 42.3470486, 
       Longititude = -71.06976929999996 
      }); 

      EntityEntry<Shelter> Mspca = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "MCSPA", 
       AddressId = MspcaAddress.Entity.AddressId 
      }); 
      EntityEntry<Shelter> BostonAnimalCareAndControl = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "Boston Animal Care And Control", 
       AddressId = BostonAnimalCareAndControlAddress.Entity.AddressId 
      }); 
      EntityEntry<Shelter> AnimalRescueLeagueOfBoston = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "Animal Rescue League Of Boston Address", 
       AddressId = AnimalRescueLeagueOfBostonAddress.Entity.AddressId 
      }); 
      DbContext.SaveChanges(); 
    } 

我試圖重新創建數據庫，查看是否有數據不一致/表的問題，但我仍然得到錯誤。有任何想法嗎？

Answer 1

您嘗試播種的「Shelter」實體要求您提交現有的AddressID上面的代碼嘗試獲取尚未創建的地址的AddressId。

您必須先提交到數據庫中的地址（使用DbContext.SaveChanges();）

然後，您可以創建與檢索到的AddressId住房的實體。下面的代碼顯示瞭如何執行此操作的示例，但是您可能必須重新編寫提取addressId的查詢。或者，您可能必須將它們與插入過程完全分開。

private void CreateShelters() 
{ 
    EntityEntry<Address> MspcaAddress = DbContext.Addresses.Add(new Address() 
    { 
       Street = "350 S Huntington Ave", 
       City = "Jamaica Plain", 
       State = "MA", 
       AreaCode = "02130", 
       Latitude = 42.3228928, 
       Longititude = -71.11120540000002 
    }); 
    EntityEntry<Address> BostonAnimalCareAndControlAddress = DbContext.Addresses.Add(new Address() 
    { 
       Street = "26 Mahler Rd", 
       City = "Roslindale", 
       State = "MA", 
       AreaCode = "02131", 
       Latitude = 42.2943377, 
       Longititude = -71.12153390000003 
      }); 
      EntityEntry<Address> AnimalRescueLeagueOfBostonAddress = DbContext.Addresses.Add(new Address() 
      { 
       Street = "10 Chandler St", 
       City = "Boston", 
       State = "MA", 
       AreaCode = "0S2116", 
       Latitude = 42.3470486, 
       Longititude = -71.06976929999996 
      }); 

    DbContext.SaveChanges(); 


      EntityEntry<Shelter> Mspca = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "MCSPA", 
       AddressId = MspcaAddress.Entity.AddressId 
      }); 
      EntityEntry<Shelter> BostonAnimalCareAndControl = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "Boston Animal Care And Control", 
       AddressId = DbContext.Addresses.Where(x => x.Street == "26 Mahler Rd").FirstOrDefault().AddressId 
     }); 
      EntityEntry<Shelter> AnimalRescueLeagueOfBoston = DbContext.Shelters.Add(new Shelter() 
      { 
       Name = "Animal Rescue League Of Boston Address", 
       AddressId = DbContext.Addresses.Where(x => x.Street == "10 Chandler St").FirstOrDefault().AddressId 

      }); 
      DbContext.SaveChanges(); 
    } 

希望這足以讓你走了。如果addressId的查詢不起作用，請告訴我，我很樂意爲您提供幫助。

Answer 2

這個問題的關鍵:)是使用引用屬性，而不是Id值。這意味着：設置Address而不是AddressId。當EF保存更改時，它會找出實體之間的依賴關係並將它們全部保存爲正確的順序，同時將生成的AddressId關鍵值恰好作爲外鍵值進行設置。

你代碼的實質（即離開了財產分配，爲簡潔起見）應該是這樣的：

var mspcaAddress = new Address(); 
var bostonAnimalCareAndControlAddress = new Address(); 
var animalRescueLeagueOfBostonAddress = new Address(); 
context.Addresses.AddRange(new[] 
{ 
    mspcaAddress, 
    bostonAnimalCareAndControlAddress, 
    animalRescueLeagueOfBostonAddress 
}); 

var mspca = new Shelter() 
{ 
    Address = mspcaAddress 
}; 
var bostonAnimalCareAndControl = new Shelter() 
{ 
    Address = bostonAnimalCareAndControlAddress 
}; 
var animalRescueLeagueOfBoston = new Shelter() 
{ 
    Address = animalRescueLeagueOfBostonAddress 
}; 
context.Shelters.AddRange(new[] 
{ 
    mspca, 
    bostonAnimalCareAndControl, 
    animalRescueLeagueOfBoston 
}); 
context.SaveChanges(); 

雖然您顯示錯誤適用於ApplicationUser的AddressId，我想在一個類似的方法創建ApplicationUser即可解決問題。

順便說一句，您可以不用第一個context.Addresses.AddRange聲明。地址將通過添加避難所而添加。

請注意，我也從代碼中刪除了EntityEntry。我認爲他們不必要地使代碼複雜化。你只需要你正在創建的簡單對象。