我最近下载了 Entity Framework Code First CTP5
,并在这种情况下遇到麻烦。我有两个表如下:
Members table : ID Name Comments table : ID Comment CommentedMemberID CommentMemberID
And, the data should be like the following:
Members ID Name 1 Mike 2 John 3 Tom Comments ID Comment CommentedMemberID CommentMemberID 1 Good 1 2 2 Good 1 3 3 Bad 2 1
Then, I coded as shown below:
public class Member
{
public int ID {get; set; }
public string Name { get; set;}
public virtual ICollection<Comment> Comments { get; set;}
}
public class Comment
{
public int ID { get; set; }
public string Comment { get; set; }
public int CommentedMemberID { get; set; }
public int CommentMemberID{ get; set; }
public virtual Member CommentedMember { get; set; }
public virtual Member CommentMember { get; set; }
}
public class TestContext : DbContext
{
public DbSet<Member> Members { get; set; }
public DbSet<Comment> Comments { get; set; }
}
但是当我在
cshtml
上运行这些模型时,它给我错误说“无法创建 CommentMember
实例”或类似的东西(抱歉,我已经更改了我的模型以进行 EF Code First 评估,因此无法重现相同的错误)。我也试过使用
OnModelCreating
在 TestContext
,但找不到任何好的说明,不知道该怎么做。我看到了一篇关于EF Code First CTP3的博文,貌似那个版本还有一个RelatedTo属性,但是现在已经没有了。谁能知道如何让它正常工作?或者这是一种完全错误的方式来处理这种情况?
谢谢,
柳
最佳答案
这是一种特殊情况,您需要使用 fluent API 来配置您的关联。这将解决问题:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Comment>().HasRequired(c => c.CommentedMember)
.WithMany(m => m.Comments)
.HasForeignKey(c => c.CommentedMemberID)
.WillCascadeOnDelete();
modelBuilder.Entity<Comment>().HasRequired(c => c.CommentMember)
.WithMany()
.HasForeignKey(c => c.CommentMemberID)
.WillCascadeOnDelete(false);
}
关于entity-framework - EF Code 一、如何实现从一张表到另一张表的两个外键?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4698233/