EF-core 如何设置多对多关系 'itself'

Question

案例：团队成员是在医院工作的任何人。团队成员（医生）可以有其他团队成员作为他们的助手（护士或其他医生），或者团队成员可以是其他团队成员的助手。

类

public class Teammember 
{
    Public int Id {get; set;}
    public ICollection<AssistantLink> AssistantLinks { get; } = new List<AssistantLink>();
    public ICollection<Teammember> Assistants => AssistantLinks.Where(x => x.CareProviderId == Id).Select(x => x.Assistant).ToList();
    public ICollection<Teammember> CareProviders => AssistantLinks.Where(x => x.AssistantId == Id).Select(x => x.CareProvider).ToList();
}

为了建立这种关系，我创建了一个 class 'AssistantLink'

   public class AssistantLink : ModelBase
    {
        public int CareProviderId { get; set; }
        public Teammember CareProvider { get; set; }
        public int AssistantId { get; set; }
        public Teammember Assistant { get; set; }
    }

在数据库上下文中，我试图通过以下方式建立这种关系：

    builder.Entity<AssistantLink>().HasKey(x => new { x.CareProviderId, x.AssistantId });
    builder.Entity<AssistantLink>().HasOne(x => x.CareProvider).WithMany("AssistantLinks"); //use string notation because navigation property is private
    builder.Entity<AssistantLink>().HasOne(x => x.Assistant).WithMany("AssistantLinks");

创建数据库迁移时，我得到以下信息

ERROR : Cannot create a relationship between 'Teammember.AssistantLinks' and 'AssistantLink.Assistant', because there already is a relationship between 'Teammember.AssistantLinks' and 'AssistantLink.CareProvider'. Navigation properties can only participate in a single relationship.

关于如何正确设置它的任何建议？

Answer 1

不可能只有一个集合具有关系。您需要两个 - 一个团队成员的 assistantlinks 等于 CareProvider，第二个团队成员的 assistantlinks 等于 Assistant.

型号

public class Teammember
{
    public int Id { get; set; }
    public ICollection<AssistantLink> Assistants { get; set; } 
    public ICollection<AssistantLink> Providers { get; set; }
}
public class AssistantLink : ModelBase
{
    public int CareProviderId { get; set; }
    public Teammember CareProvider { get; set; }
    public int AssistantId { get; set; }
    public Teammember Assistant { get; set; }
}

配置：

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AssistantLink>()
            .HasKey(x => new { x.CareProviderId, x.AssistantId });
        modelBuilder.Entity<AssistantLink>()
            .HasOne(al => al.CareProvider)
            .WithMany(c => c.Providers)
            .HasForeignKey(al => al.CareProviderId)
            .OnDelete(DeleteBehavior.Restrict);
        modelBuilder.Entity<AssistantLink>()
            .HasOne(al => al.Assistant)
            .WithMany(a => a.Assistants)
            .HasForeignKey(al => al.AssistantId)
            .OnDelete(DeleteBehavior.Restrict); 
    }