我的數據庫中有兩個表。一個叫Users
,另一個叫Widgets
。 Widgets
表代表我的代碼模型中的3個實體。其中一個實體Widget
是其他兩個實體的父級,WidgetTypeA
和WidgetTypeB
。 WidgetTypeA
和WidgetTypeB
都對用戶實體具有導航屬性,該用戶實體持久保存到數據庫的用戶表中。我無法讓Code First爲WidgetTypeA
和WidgetTypeB
實體(UserId
)使用相同的外鍵。有誰知道如何做到這一點?它似乎應該是表每個層次結構映射的常見問題。關於EF代碼的困難首先流利的API,TPH和外鍵
我的實體類如下:
public class Widget
{
public int Id { get; set; }
public string Name { get; set; }
}
class WidgetMap : EntityTypeConfiguration<Widget>
{
public WidgetMap()
{
ToTable("Widgets");
HasKey(w => w.Id);
Property(w => w.Id)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
Property(w => w.Name)
.IsRequired()
.HasMaxLength(75)
.IsUnicode(true);
}
}
public class WidgetTypeA : Widget
{
public int UserId { get; set; }
public virtual User User { get; set; }
public string Color { get; set; }
public int DepthLevel { get; set; }
}
class WidgetTypeAMap : EntityTypeConfiguration<WidgetTypeA>
{
public WidgetTypeAMap()
{
Map(w => w.Requires("WidgetTypeId").HasValue(1));
HasRequired(w => w.User)
.WithMany(u => u.WidgetTypeAs)
.HasForeignKey(w => w.UserId)
.WillCascadeOnDelete(false);
Property(w => w.Color)
.IsOptional()
.IsUnicode(true)
.HasMaxLength(75);
Property(w => w.DepthLevel)
.IsOptional();
}
}
public class WidgetTypeB : Widget
{
public int UserId { get; set; }
public virtual User User { get; set; }
}
class WidgetTypeBMap : EntityTypeConfiguration<WidgetTypeB>
{
public WidgetTypeBMap()
{
Map(w => w.Requires("WidgetTypeId").HasValue(2));
HasRequired(w => w.User)
.WithMany(u => u.WidgetTypeBs)
.HasForeignKey(w => w.UserId)
.WillCascadeOnDelete(false);
}
}
public class User
{
public int Id { get; set; }
public string Username { get; set; }
public int Age { get; set; }
public virtual ICollection<WidgetTypeA> WidgetTypeAs { get; set; }
public virtual ICollection<WidgetTypeB> WidgetTypeBs { get; set; }
}
class UserMap : EntityTypeConfiguration<User>
{
public UserMap()
{
ToTable("Users");
HasKey(u => u.Id);
Property(u => u.Username)
.IsRequired()
.HasMaxLength(75)
.IsUnicode(true);
Property(u => u.Age)
.IsRequired();
}
}
無論如何,我不斷收到錯誤
無效的列名稱UserId1「
,當我嘗試執行以下操作:
using (var entities = new MyEntities())
{
User u = new User
{
Username = "Frank",
Age = 14
};
entities.Users.Add(u);
entities.SaveChanges();
WidgetTypeA wa1 = new WidgetTypeA
{
Name = "0SDF81",
UserId = u.Id,
DepthLevel = 6
};
entities.WidgetTypeAs.Add(wa1);
entities.SaveChanges();
}
不確定這是否可以修復。我總是可以爲Widgets表指定第二個UserId外鍵,但這似乎毫無意義。也許有一種方法可以使用Fluent API來做到這一點?