EF 6 Fluent API，具有一對多，多對多且相互沖突的多重性

Question

我一直無法找到這個特定問題的答案，也許是我使用Entity Framework的新穎性

我有兩個實體：用戶和設施。

設施表需要所有者（用戶），但是設施也可以有許多“設施用戶”分配給設施。

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; }
}

這是我的ModelBuilder

////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);

問題是，當我將Facility映射到Owner時 ，出現以下錯誤： 在類型'MEH.Web.Models.Entities.Facility'上聲明的導航屬性'FacilityUsers'已配置有沖突的多重性 。

但是，當我排除“ 設施到所有者”映射時，它可以工作。

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

問題是， Facilitys表中的Owner_UserId字段為空，但是OwnerId已正確填寫。在解決“ Owner_UserId”問題之前，我的OCD不允許我繼續前進。

謝謝你D

Answer 1

您不能將一個集合導航屬性（ Facilities ）映射到兩個關系。

為one-to-many關系添加另一個集合：

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

並映射它：

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

或保持User模型不變，但將one-to-many關系配置為單向 （無集合導航屬性）：

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