EF代码第一：多对多和一对多 [英] EF Code First: Many-to-many and one-to-many

问题描述

这可能只是因为我缺乏EF Code First流利的API的知识，但我很累。

This is probably just because my knowledge with the EF Code First fluent API is lacking, but I'm stumped.

我想建模如下：

• 群组集合（含ID和名称）


• 的集合
  
• 每个用户只分配给一个主组


• 每个用户可能有零个或多个次组

• A Groups collection with Id and Name
• A Users collection with Id and Name
• Each user is assigned to exactly one primary group
• Each user may have zero or many secondary groups

我要使用的表结构如下：

The table structure I'm going for would look like:

strong>群组

Groups

• Id


• 姓名

使用者

• 
  
• 姓名


• PrimaryGroupId

SecondaryGroupAssignments

• UserId


• GroupId

我一直在对着墙试图用EF Code First建模，但我不能让它接受用户和组之间的关系。对不起，没有发布任何.NET代码（我很高兴），但它可能都是错误无论如何。

I've been beating my head against a wall trying to model this with EF Code First, but I can't get it to accept both relationships between User and Group. Sorry for not posting any .NET code (I'm happy to), but it's probably all wrong anyway.

有没有办法使EF模型？我假设我必须用Fluent API做一些配置。也许一个更好的问题是：有没有任何好的，明确的参考为Fluent API？

Is there a way to make EF model this? I'm assuming I have to do some sort of configuration with the Fluent API. Maybe a better question is: is there any good, definitive reference for the Fluent API?

谢谢！

推荐答案

尝试这个（未测试的）：

Try this (untested):

public class Group 
{
    public int Id { get; set; }
    public string Name { get; set; }

    public virtual ICollection<User> PrimaryUsers { get; set; }
    public virtual ICollection<User> SecondaryUsers { get; set; } 
}

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int PrimaryGroupId { get; set; }

    public virtual Group PrimaryGroup { get; set; }
    public virtual ICollection<Group> SecondaryGroups { get; set; }
}

public class Context : DbContext
{
    public DbSet<User> Users { get; set; }
    public DbSet<Group> Groups { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<User>()
                    .HasRequired(u => u.PrimaryGroup)
                    .WithMany(g => g.PrimaryUsers)
                    .HasForeignKey(u => u.PrimaryGroupId)
                    .WillCascadeOnDelete(false);

        modelBuilder.Entity<User>()
                    .HasMany(u => u.SecondaryGroups)
                    .WithMany(g => g.SecondaryUsers)
                    .Map(m => m.MapLeftKey("UserId")
                               .MapRightKey("GroupId")
                               .ToTable("SecondaryGroupAssignments"));
    }
}

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