一到一個在每一個分層

Question

public class BasePage 
{   
    public int Id { get; set; } 
    ... 
} 

public class Region : BasePage 
{   
    public virtual MapCoordinates Map { get; set; } 
    ... 
} 

public class Place: BasePage 
{   
    public virtual MapCoordinates Map { get; set; } 
    ... 
} 

public class MapCoordinates 
{ 
    [Key, ForeignKey("BasePage")] 
    public int Id { get; set; } 

    public virtual BasePage BasePage { get; set; } 
    ... 
} 

獲取有關的SaveChanges此異常表：

無法確定相關的操作有效的排序。由於外鍵約束，模型要求或商店生成的值，可能會存在依存關係。

Answer 1

使用此代碼：

public class BasePage 
    {   
     public int Id { get; set; } 

     public virtual MapCoordinate Map { get; set; } 
     ... 
    } 

    public class Region : BasePage 
    {     
     ... 
    } 

    public class Place: BasePage 
    {   
     ... 
    } 

    public class MapCoordinate 
    { 
     [Key] 
     public int BasePageId { get; set; } 
     ... 
    } 

    protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
     modelBuilder.Entity<BasePage>() 
        .HasRequired(e => e.MapCoordinate) 
        .WithRequiredPrincipal(); 

     modelBuilder.Entity<BasePage>().ToTable(BasePages); 
     modelBuilder.Entity<MapCoordinate>().ToTable(MapCoordinates); 
    } 

請查看以下鏈接：

Associations in EF Code First: Part 4 – Table Splitting

Associations in EF Code First: Part 5 – One-to-One Foreign Key Associations

Code First and Fluent API one to one relationship