实体框架多对多关系插入不起作用

Question

我有两个具有多对多关系的表： ActionPlan和Responsible 。

当我插入一个新的ActionPlan和新的Responsible ，表ActionPlanResponsible上的记录被正确创建，但是当我尝试添加一个具有现有Responsible的新ActionPlan时，表ActionPlanResponsible的记录没有被创建。

我以这种方式在 Json 中传递 ActionPlan 和 Responsible：

{

"What": "Whatttasdasdt",
"Why": "Whyasdyyyy",
"How": "Hoasdwwwww",
"StartDate": "28/09/2015",
"EndDate": "28/09/2015",
"CreateDate": "28/09/2015",
"UpdateDate": "28/09/2015",
"State": "1",
"Where" : "Whasdere",
"Goal": {
    "Id": "10"
},
"Responsibles": [{

    "Id": "15"
}]

这就是我在 EF 中处理请求的方式...

foreach (var r in actionPlan.Responsibles)
{
    context.Responsible.Attach(r);
}

context.ActionPlan.Add(actionPlan); 

context.SaveChanges();
transaction.Commit();

ActionPlan 实体：

 public long Id { get; set; }

    public string What { get; set; }

    public string Why { get; set; }

    public string How { get; set; }

    public DateTime StartDate { get; set; }

    public virtual ICollection<Responsible> Responsibles { get; set; }

    public DateTime EndDate { get; set; }

    public Goal Goal { get; set; }

    public virtual ICollection<FileActionPlan> Files { get; set; }

    public virtual ICollection<Comment> Comments { get; set; }

    public string Where { get; set; }

    public virtual ICollection<Task> Tasks { get; set; }

责任单位：

 public byte State { get; set; }

    public DateTime CreateDate { get; set; }

    public DateTime UpdateDate { get; set; }

    //public virtual ICollection<ActionPlan> ActionPlans { get; set; }

    public virtual ICollection<Task> Tasks { get; set; }

    public long Id { get; set; }

    public Guid PersonId { get; set; }

Answer 1

您还必须将Responsibles添加到actionPlan.Responsibles ：

foreach (var r in actionPlan.Responsibles)
{
    context.Responsible.Attach(r);
    actionPlan.Responsibles.Add(r);
}

context.ActionPlan.Add(actionPlan); 

这不会创建新的Responsibles而是建立关联，因此 EF 知道它应该插入连接记录。