使用外鍵作爲主鍵

Question

我有一個有很多關係的數據庫。不幸的是，它是一箇舊的維護數據庫，似乎並不瞭解關聯或密鑰的概念，有時它缺少這個概念。它的主要用途是在另一個應用程序，因此我最不願改變數據庫（而是配置實體框架）

我的問題是試圖使用外鍵作爲主鍵，因爲（我猜）關聯表用它。

我的表稱爲

Operation{ Criteria { Parameter{ CriteriaSelection { 
    ID   ID,   ID,   ID, 
    ..   ..   ..   .. 
}    }    }    } 

CheckpointOperation { 
    ID, 
    Criteria_ID, 
    .. 
} 

CheckpointParameter { 
    // missing primary key 
    CheckpointOperation_ID, // a CheckpointOperation has many CheckpointParameters 
    CriteriaSelection_ID, // a CheckpointParameter has one CriteriaSelection 
    Parameter_ID,   // .. and one Parameter 
    .. 
} 

這裏的問題是，CheckpointParameter沒有明確定義了主鍵，而是{ CheckpointOperation_ID, CriteriaSelection_ID, Parameter_ID }的主鍵。現在我試圖在EntityFramework中將它映射爲class CheckpointParameterMap : EntityTypeConfiguration<CheckpointParameter>。

public class CheckpointOperation 
{ 
    public int Id { get; set; } 
    public virtual Operation Operation { get; set; } 

    public virtual ICollection<CheckpointParameter> Parameters { get; set; } 
} 

public class CheckpointParameter 
{ 
    public int OperationId { get; set; } 

    public virtual CheckpointOperation CheckpointOperation { get; set; } 
    public virtual CriteriaSelection Criteria { get; set; } 
    public virtual QualityParameter Parameter { get; set; } 
} 

public class CheckpointParameterMap : EntityTypeConfiguration<CheckpointParameter> 
{ 
    public CheckpointParameterMap() 
    { 
     HasKey(p => new { p.OperationId }); 

     Property(p => p.OperationId) 
      .HasColumnName("CheckpointOperation_ID"); 

     HasRequired(p => p.CriteriaSelection) 
      .WithRequiredDependent() 
      .Map(map => map.MapKey("CriteriaSelection_ID")); 

     HasRequired(p => p.Parameter) 
      .WithRequiredDependent() 
      .Map(map => map.MapKey("Parameter_ID")); 

     HasRequired(p => p.CheckpointOperation) 
      .WithMany(o => o.CheckpointParameters) 
      .HasForeignKey(p => p.OperationId); 
    } 
} 

但是這給了我一個錯誤的

Multiplicity is not valid in Role 'CheckpointParameter_CheckpointOperation_Source' in relationship 'CheckpointParameter_CheckpointOperation'. Because the Dependent Role refers to the key properties, the upper bound of the multiplicity of the Dependent Role must be '1'.\r\n"}

所以我試圖刪除HasKey，但給我的

EntityType 'CheckpointParameter' has no key defined. Define the key for this EntityType.\r\n\tSystem.Data.Entity.Edm.EdmEntitySet: EntityType: EntitySet 'CheckpointParameters' is based on type 'CheckpointParameter' that has no keys defined.\r\n"}

錯誤於是我試圖用外國CriteriaSelectionId以及主鍵，因爲我有列名：

public class CheckpointParameter 
{ 
    ... 
    public int CriteriaSelectionId { get; set; } 
    ... 
} 

public CheckpointParameterMap() 
{ 
    HasKey(p => new { p.OperationId, p.CriteriaSelectionId }); 
    //... 
    Property(checkpointParameter => checkpointParameter.CriteriaSelectionId) 
     .HasColumnName("CEC_ID"); 
} 

但是這給了我以下錯誤：

{"Schema specified is not valid. Errors: \r\n(48,6) : error 0019: Each property name in a type must be unique. Property name 'CriteriaSelection_ID' was already defined."}

什麼是定義主鍵的正確方法，這是外鍵，而無需修改數據庫？

Answer 1

您需要映射的標準和操作添加哪些領域會是這樣的參考：

this.HasKey(x => x.OperationId); // In Operation Mapping 

this.HasKey(x => x.CriteriaId); // In Criteria Mapping 

而且在標準或工作，你應該映射一些這樣的：

this.HasMany(b => b.Criterias) 
    .WithMany(x=> x.Operations) 
    .Map(x => 
    { 
     x.ToTable("CheckpointParameter"); 
     x.MapLeftKey("CriteriaId"); 
     x.MapRightKey("OperationId"); 
    });