删除使用Ajax.actionlink

Question

我有我的asp.net MVC应用程序内的以下观点，即包含了删除对象的ajax.actionlink对象处理的并发访问方法将由上述AJAX链接被称为： -

[HttpPost] 
     public void Delete(int id) 
     {  var a = repository.FindAnswer(id); 
       repository.DeleteAnswer(a); 
       repository.Save();} 

和folloiwng的onSuccess脚本： -

function deleteconfirmation3(rid, rname) { 
    $('#' + rid).remove(); 
    jAlert(rname + ' Was Deleted Succsfully succsfully', 'Deletion Confirmation');} 

当前，如果两个用户访问相同的视图，然后他们都点击与同一对象关联的删除链接，则会在其中一个请求上引发空异常;所以我如何在动作方法和视图方面处理这个问题，以向用户显示友好的消息;在这两种情况下： -

1. 要么当var a = repository.FindAnswer(id);返回空值 异常？
2. 或者当repository.Save();没有删除任何记录？

BR

编辑： -

我更新了帖子行动方法如下： -

[HttpPost] 
    public ActionResult Delete(int id) 
    { 

     try 
     { 
      Thread.Sleep(1000); 
      var a = repository.FindAnswer(id); 

      repository.DeleteAnswer(a); 
      repository.Save(); 
      return Json(new { IsSuccess = "True", id = id, description = a.Description }, JsonRequestBehavior.AllowGet); 
     } 
     catch (ArgumentNullException) { 
      return Json(new { IsSuccess = "False" }, JsonRequestBehavior.AllowGet); }} 

，并在视图我更新ajax.actionlink到folloiwng ： -

@{ string i = "Are uou sure you want to delete " + @answer.Description.ToString() + " ?";} 
     @Ajax.ActionLink("Delete", "Delete", "Answer", 
     new { id = answer.AnswersID }, 
      new AjaxOptions 
      { 
       //OnBegin = "deleteconfirmation1", 
       Confirm = i, 
       HttpMethod = "Post", 
       OnBegin = string.Format(
         "disablelink({0})", 
         Json.Encode(answer.AnswersID)), 

       OnSuccess = "myresponse" 
     }) 

和的onSuccess脚本： -

function myresponse(data) { 
    if (data.IsSuccess == "True") 
    { 
     $('#' + data.id).remove(); 
     jAlert(data.description + ' Was Deleted Succsfully succsfully', 'Deletion Confirmation'); 
    } 
    else { 
     $('#' + data.id).remove(); 
     jAlert(data.description + 'record has already been deleted', 'aaaa'); 
    } 
} 

上面的代码工作时，我测试了罚款,,但这种方法听起来可以接受的，我没有写类似这样的东西之前？ BR

Answer 1

添加一个检查，以便如果记录存在，删除它，否则显示一条消息，指明该记录已被删除...

[HttpPost] 
public ActionResult Delete(int id) 
{  var a = repository.FindAnswer(id); 
     if(/*check if a is not null*/){ 
     repository.DeleteAnswer(a); 
     repository.Save(); 
     return Json(new{ IsSuccess="True", id=id,description=a.Description }); 
     }else{ 
      // display a message record already been deleted 
      return Json(new{ IsSuccess="False" }); 
     }  

} 

apparantly你将需要改变的返回类型从无效到ActionResult或JsonResult

@Ajax.ActionLink("Delete", "Delete", "Answer", 
     new { id = answer.AnswersID }, 
      new AjaxOptions 
      { 
       Confirm = i, 
       HttpMethod = "Post", 
       OnBegin = string.Format(
         "disablelink({0})", 
         Json.Encode(answer.AnswersID)), 
       OnSuccess = "myResponse" 
      }) 

的成功处理程序会像

function myResponse(data){ 
if(data.IsSuccess=="True") 
    jAlert(data.description + ' Was Deleted Succsfully succsfully', 'Deletion Confirmation'); 
    else { 
    alert("record has already been deleted"); 
    } 

}