实体框架代码优先:如何映射多个自引用多对多关系

Question

我创建了一个实体类型,它具有多个引用相同类型项的集合属性.换句话说,它反映了单个数据库表,其中行被任意分组,使得行可以出现在多个组中.

在下面的简化示例中,Person类有Brothers和Sisters集合属性也引用Person实体:

public class Person
{
    public Person()
    {
        Brothers = new Collection<Person>();
        Sisters = new Collection<Person>();
    }

    [Key]
    public string Name { get; set; }

    public int Age { get; set; }

    public virtual ICollection<Person> Brothers { get; set; } 

    public virtual ICollection<Person> Sisters { get; set; } 
}

实体框架似乎认为这是一个有效的模型,但是将其解释为创建单个PersonPersons连接表,这无法反映兄弟姐妹关系的分离.

我假设解决方案是使用流畅的API为两个关系显式映射单独的连接表,但是,尽管经过了大量的实验,我仍然无法使其工作.

有什么建议吗？

蒂姆,谢谢

Answer 1

通过在DbContext.OnModelCreating方法中添加它:

更新根据nameEqualsPNamePrubeGoldberg上面的评论添加了表命名映射:

modelBuilder.Entity<Person>().HasMany(x => x.Brothers).WithMany()
    .Map(x => x.ToTable("Person_Brothers"));
modelBuilder.Entity<Person>().HasMany(x => x.Sisters).WithMany()
    .Map(x => x.ToTable("Person_Sisters"));

我通过了这个单元测试

[TestMethod]
public void TestPersons()
{
    var brother = new Person() { Name = "Brother 1", Age = 10 };
    var sister = new Person() { Name = "Sister 1", Age = 12 };
    var sibling = new Person() { Name = "Sibling 1", Age = 18 };
    sibling.Brothers.Add(brother);
    sibling.Sisters.Add(sister);

    using (var db = new MyDatabase())
    {
        db.Persons.Add(brother);
        db.Persons.Add(sister);
        db.Persons.Add(sibling);

        db.SaveChanges();
    }

    using (var db = new MyDatabase())
    {
        var person = db.Persons
            .Include(x => x.Sisters)
            .Include(x => x.Brothers)
            .FirstOrDefault(x => x.Name.Equals(sibling.Name));

        Assert.IsNotNull(person, "No person");
        Assert.IsTrue(person.Brothers.Count == 1, "No brothers!");
        Assert.IsTrue(person.Sisters.Count == 1, "No sisters");
    }
}

这也创建了您正在谈论的链接表.