EF 4.1 RC EF CF 中的多对多关系

发布于 2024-10-31 03:05:54 字数 478 浏览 4 评论 0原文

我有两个具有多对多关系的实体，如下所示：

class author
{
  public int AuthorID{get;set;}
  public string Name{get;set;}
  public virtual ICollection<book> books{get;set;}
}
class book
{
  public int BookID{get;set;}
  public string Name{get;set;}
 public virtual ICollection<author> authors{get;set;}

}

并且我有一个名为 Bookauthor 的中间表，定义如下：

  BookAuthor: int
  int AuthorID
  int BookID

如何使用 FluentAPI 映射此表

谢谢！

原文

I have two entities with many to many relationship like this:

class author
{
  public int AuthorID{get;set;}
  public string Name{get;set;}
  public virtual ICollection<book> books{get;set;}
}
class book
{
  public int BookID{get;set;}
  public string Name{get;set;}
 public virtual ICollection<author> authors{get;set;}

}

and I have an intermediate table named Bookauthor defined like this:

  BookAuthor: int
  int AuthorID
  int BookID

How to map this using FluentAPI

Thanks!!

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清风疏影 2024-11-07 03:05:54

这在 EDMX 中是有问题的，但在 EF 4.1 Fluent API 中您可以映射它：

modelBuilder.Entity<book>()
            .HasMany(b => b.authors)
            .WithMany(a => a.books)
            .Map(m => m.MapLeftKey("BookID")
                   .MapRightKey("AuthorID")
                   .ToTable("BookAuthor"));

如您所见，我没有映射 BookAuthor 列。该列对于 EF 来说是未知的，并且必须自动递增。

这显然不适用于代码优先方法，但前提是您对现有数据库使用 Fluent API。

This was problematic with EDMX but with EF 4.1 fluent API you can map it:

modelBuilder.Entity<book>()
            .HasMany(b => b.authors)
            .WithMany(a => a.books)
            .Map(m => m.MapLeftKey("BookID")
                   .MapRightKey("AuthorID")
                   .ToTable("BookAuthor"));

As you can see I don't map BookAuthor column. That column is unknown to EF and must be auto incremented.

This obviously can't work with a Code-first approach but only if you use Fluent API against existing database.

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