EF 6 Fluent API 具有一对多和多对多以及相互冲突的多重性

Question

我没能找到这个具体问题的答案，也许是因为我对 Entity Framework

很陌生

我有两个实体：用户和设施。

设施 table 需要一个所有者（用户），但一个设施也可以有多个 "FacilityUsers" 分配给一个设施。

public class User
{
    ....
    public virtual ICollection<Facility> Facilities { get; set; }
}

public Facility Facility
{
    public Guid OwnerId { get; set; }
    ...
    public virtual User Owner { get; set; }
    public virtual ICollection<User> FacilityUsers { get; set; }
}

这是我的模型构建器

////Many To Many: Users To Facilities
modelBuilder.Entity<User>()
    .HasMany(i => i.Facilities)
    .WithMany(u => u.FacilityUsers)
    .Map(m =>
    {
        m.MapLeftKey("UserId");
        m.MapRightKey("FacilityId");
        m.ToTable("UserFacility");
    });        

//One to Many: Facility To Owner
modelBuilder.Entity<Facility>()
    .HasRequired<User>(s => s.Owner)
    .WithMany(s => s.Facilities)
    .HasForeignKey(k => k.OwnerId);

问题是，当我有地图 Facility to Owner 时，我收到以下错误：The navigation 属性 'FacilityUsers' 在类型 'MEH.Web.Models.Entities.Facility' 上声明已配置有冲突的多重性 。

但是，当我排除 Facility to Owner 映射时，它起作用了。

//One to Many: Facility To Owner
//modelBuilder.Entity<Facility>()
//    .HasRequired<User>(s => s.Owner)
//    .WithMany(s => s.Facilities)
//    .HasForeignKey(k => k.OwnerId);

问题是，Facilities table 然后有一个 Owner_UserId 字段为空，但是OwnerId 已正确填写。在我解决 "Owner_UserId" 问题之前，我的强迫症不会让我继续前进。

谢谢， D

Answer 1

您不能将一个 集合导航属性 (Facilities) 映射到两个 关系。

为 one-to-many 关系添加另一个集合：

public class User
{
    ....
    public virtual ICollection<Facility> Facilities { get; set; }
    public virtual ICollection<Facility> OwnedFacilities { get; set; }
}

并映射它：

//One to Many: Facility To Owner
modelBuilder.Entity<Facility>()
    .HasRequired(s => s.Owner)
    .WithMany(s => s.OwnedFacilities) // <- another collection
    .HasForeignKey(k => k.OwnerId);

或者保持现在的User模型，但是将one-to-many关系配置为单向（没有集合导航属性）：

//One to Many: Facility To Owner
modelBuilder.Entity<Facility>()
    .HasRequired(s => s.Owner)
    .WithMany() // <- no collection
    .HasForeignKey(k => k.OwnerId);