实体框架：更新对象失败，重复键

我有一个类Activity，它与一些部门相关联。实体框架：更新对象失败，重复键

public class Activity 
{ 
... 

    public int Id { get; set; } 




    public virtual List<Department> ParticipantDepartments { get; set; } 


}

这是控制器中的动作，它接受用户的编辑。在用户编辑之前，activity已经与数据库中的某个ParticipantDepartments相关联。现在我们假设用户修改ParticipantDepartments，然后在POST方法更改ParticipantDepartments到新的用户定义的一个：

// POST: Activities/Edit/5 
     // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
     // more details see http://go.microsoft.com/fwlink/?LinkId=317598. 
     [HttpPost] 
     [ValidateAntiForgeryToken] 
     public ActionResult Edit(
     EditActivityViewModel editActivityViewModel) 
     { 


      if (ModelState.IsValid) 
      { 
       Activity activity = db.Activities.Find(editActivityViewModel.ActivityId); 

       activity. 
        Category = editActivityViewModel.Category; 
       activity.DetailedLocation = editActivityViewModel.DetailedLocation; 
       activity.District = editActivityViewModel.District; 
       activity.Linkman = editActivityViewModel.Linkman; 
       activity.Phone = editActivityViewModel.Phone; 
       activity.Title = editActivityViewModel.Title; 
       activity.TotalParticipantsAmount = editActivityViewModel.TotalParticipantsAmount; 
       activity.particular = editActivityViewModel.particular; 
       activity.OriginatorId = User.Identity.GetUserId(); 
       activity.ParticipantDepartments = GetParticipantDepartments(editActivityViewModel.SelectedDepartmentIds); 

       List<Models.ActivityTime> activityTimes = new List<Models.ActivityTime>(); 
       foreach (var item in editActivityViewModel.ActivityTimes) 
       { 
        Models.ActivityTime activityTime = new Models.ActivityTime 
        { 
         StartTime = item.StartDate + item.StartTime, 
         EndTime = item.EndDate + item.Endtime 
        }; 
        activityTimes.Add(activityTime); 
       } 
       activity.AcvitityTimes = activityTimes; 


       db.SaveChanges(); 
       return RedirectToAction("Index"); 
      } 

      return View(editActivityViewModel); 
     }

然而，asp.net暗示

违反PRIMARY KEY约束“PK_dbo.DepartmentActivities ”。无法在对象'dbo.DepartmentActivities'中插入重复键。重复的键值是（13，1008）。
该声明已被终止。

发生在用户修改ParticipantDepartments时，但仍有部分与以前相同，可以接受。但是，实体框架似乎不知道它。所以它只是在表dbo.DepartmentActivities中插入一条新记录。

问题是，如何解决这个问题？我应该找到某种方式来“先删除数据库中的所有相关部门，然后更新activity像我张贴在这里，还是应该找到某种方式来让实体框架知道我已经跟activity？

相关的一些部门

编辑：

private List<Department> GetParticipantDepartments(List<List<int>> selectedDepartmentIds) 
     { 
      List<Department> departments = new List<Department>(); 
      foreach (var selectedDepartmentId in selectedDepartmentIds) 
      { 
       departments.Add(AccountController.GetDepartment(selectedDepartmentId, db)); 
      } 
      return departments; 
     }

来源

2017-02-24 guo

你能告诉我GetParticipantDepa rtments（editActivityViewModel.SelectedDepartmentIds）;方法 – jitender

@jitender请参阅更新。 – guo

@jitender'GetParticipantDepartments'只分析用户的输入并返回'List ' – guo

我认为SelectedDepartmentIds是List<int>

//this will add new departments 

var newDepartmentIds = editActivityViewModel.SelectedDepartmentIds.Where(sdid => activity.ParticipantDepartments.All(pd => pd.Id != sdid)).ToList(); 

activity.ParticipantDepartments.Add(GetParticipantDepartments(newDepartmentIds)); 

//if you also want to remove the departments those are not in editActivityViewModel.SelectedDepartmentIds 

activity.ParticipantDepartments.RemoveRange(activity.ParticipantDepartments.Where(apd => editActivityViewModel.SelectedDepartmentIds.All(sdid => sdid != apd.Id)))

来源

2017-02-24 05:23:23 jitender

实体框架：更新对象失败，重复键

回答

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