实体框架许多一对多的关系 [英] Entity framework many-to-many relationship

问题描述

好吧，我想弄清楚如何设置我的数据库正常。

Ok, I'm trying to figure out how to setup my DB properly.

我有两个类：

public class Event
{
    public int EventId { get; set; }
    public string EventName { get; set; }
}

和

public class Dog
{
    public int DogId { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

的事件必须能够包含狗的集合。
每只狗必须能够在任何情况下的部分。
我猜这就是他们所谓的很多一对多的关系，但是我现在该怎么用钥匙等。我希望我是什么，我希望达到足够清晰设置它没有。

An event must be able to contain a collection of dogs. Every dog must be able to be part in any event. I'm guessing this is what they call a many-to-many relationship, but I do not now how to set it up with keys etc. I hope I'm clear enough with what I'm hoping to achieve.

昨天我问过类似的问题，但我当时没有结束，我需要什么明确的：
有对象作为一个外键的列表。

I asked a similar question yesterday but I was then not clear over what I needed: Have a list of objects as a foreign key.

谢谢！

推荐答案

是的，这是一个N：N的关系。假设code首先，改变你的实体：

Yes, that is a N:N relationship. Assuming Code First, change your entities:

public class Event
{
    public Event()
    {
       Dogs = new HashSet<Dog>();
    }
    public int EventId { get; set; }
    public string EventName { get; set; }
    public virtual ICollection<Dog> Dogs { get; set; }
}

public class Dog
{
    public Dog()
    {
       Events = new HashSet<Event>();
    }
    public int DogId { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public virtual ICollection<Event> Events { get; set; }
}

和您的 OnModelCreating ：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
  modelBuilder.Entity<Dog>()
    .HasMany(d => d.Events)
    .WithMany(e => e.Dogs)
    .Map(m =>
    {
       m.MapLeftKey("DogId");
       m.MapRightKey("EventId");
       m.ToTable("DogEvent");
    });
}

这应该然后创建一个路口表 DogEvent 只用两个外键， DogId 和 EVENTID

This should then create a junction table DogEvent with just the two foreign keys, DogId and EventId

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