LoadViewState中的对象引用为null？

Question

检查LoadViewState中是否单击了按钮

我收到了这个错误

Object reference null

在下面的代码中，如果我点击添加体验按钮时 eTarget = Request.Params["btnAddVisa"].ToString();获取空错误

代码：

protected override void LoadViewState(object savedState)
{
  base.LoadViewState(savedState);
  if(IsPostBack)
  {

  eTarget = Request.Params["btnAddVisa"].ToString();
  eTarget = Request.Params["btnAddExperience"].ToString();
  }

  if(eTarget == "Add Visa")
  {
    //
  }

  if(eTarget == "Add Experience")
  {
    //
  }
}

protected void btnAddVisa_Click(sender,e)
{
  //
}

protected void btnAddExperience_Click(sender,e)
{
  //
}

有什么想法吗？提前致谢

Answer 1

Request.Params["btnAddVisa"] may not have any object or value.

Answer 2

您需要检查空值

if(Request.Params["btnAddVisa"]!=null)
    eTarget = Request.Params["btnAddVisa"].ToString();
if(Request.Params["btnAddExperience"]!=null)
    eTarget = Request.Params["btnAddExperience"].ToString();