添加控件列表并循环翻转 [英] Add control to list and loop overthem

问题描述

我的asp页面中有多个GridView，我希望通过将它们插入列表来循环它们

然而这会在运行时抛出异常

i知道我遗失的东西



我的代码是：

列表< object> grdvw; 
 受保护  void  Page_Load（ object  sender，EventArgs e）
 {
 
 
 grdvw.Add（GridView1）; 
 grdvw.Add（GridView2）; 
 grdvw.Add（GridView3）; 
 grdvw.Add（GridView4）; 
 grdvw.Add（GridView5）; 
 grdvw.Add（GridView6）; 
 grdvw.Add（GridView7）; 
 grdvw.Add（GridView8）; 
 grdvw.Add（GridView9）; 
 grdvw.Add（GridView10）; 
 
  //  不计算清单： 
  var  waitingDoc =（来自 wdoc   db.waitings 
  join  doc  in  db.Emplyees on wdoc.DoctorId equals doc.EmpID 
 < span class =code-sdkkeyword> where  wdoc.dismissed！=  2  
  select   new  {doc.EmpName，doc.EmpID}）。Distinct（）; 
  int  doctors = waitingDoc.Count（）; 
 
 docCountlbl.Text = doctors.ToString（）; 
 
  int  li =  0 ; 
  if （waitingDoc.Count（）>   0 ）
 {
 
  foreach （ var  docdata  in  waitingDoc）
 {
 
  //  使div和gridview可见 
 
  foreach （Control TempControl  in   this  .Form.Controls）
 {
  if （TempControl   GridView&& TempControl.ID == grdvw [li]）
 {
 
 GridView TempGridView = TempControl  as  GridView; 
 TempGridView.Visible =  true ; 
} 
} 
 
  foreach （Control TempControl  in   this  .Form.Controls）
 {
  if （TempControl.ID = = divesion [li]）
 {
 
 TempControl.Visible =  true ; 
} 
} 
  //  清除数据 
 waiting.Clear（）; 
 
 
 
  //  列heades  
 
  string  DocName =（ from  doctr  in  db.Emplyees 
 其中 doctr.EmpID == docdata.EmpID 
 选择 doctr.EmpName）。 Single （）; 
 waiting.Columns.Add（  postion）; 
 waiting.Columns.Add（  Dr + DocName）; 
 waiting.Columns.Add（  s）; 
 
  //  获取数据和索引 
  var  witingList = 来自等待  db.waitings 
  join  doc  in  db.Emplyees on wait.DoctorId equals doc.EmpID 
  join  cli  in  db.Clints on wait.clintID equals cli.ClintID 
  where  wait.dismissed！=  2 && doc.EmpID == docdata.EmpID 
 选择  new  {ClintName = cli.Name，position = wait.dismissed}; 
 
  int  noFrows = witingList.Count（）; 
  int  i =  1 ; 
  foreach （ var  item  in  witingList）
 {
 DataRow lin = waiting.NewRow（）; 
 lin [ 2 ] = i; 
 lin [ 1 ] = item.ClintName.ToString（）; 
 
 
  if （item.position ==  1 ）
 {
 lin [ 0 ] =  诊所; 
 
} 
 
  if （item.position ==  0 ）
 {
 lin [ 0 ] =  等待; 
 
} 
  if （item.position ==  3 ） 
 {
 lin [ 0 ] =  成品; 
 
} 
 
 i ++; 
 waiting.Rows.Add（lin）; 
} 
 
 
 
} 
 
 
} 
} 
} 

当我运行它给我这个例外





< pre lang =text>对象引用未设置为对象的实例。
描述：执行当前Web请求期间发生了未处理的异常。请查看堆栈跟踪以获取有关错误及其源自代码的位置的更多信息。

异常详细信息：System.NullReferenceException：未将对象引用设置为对象的实例。

来源错误：


第18行：
第19行：
第20行：grdvw.Add（GridView1）;
第21行：grdvw.Add（GridView2）;
第22行：grdvw.Add（GridView3）;

解决方案

对我来说，看起来你的全局变量grdvw可能没有被初始化。在你的PageLoad功能中你可以试试这个。

 如果（ grdvw ==  null ）
 
 {
 grdvw =  new  List< ;对象>（）; 
} 

I have multiple GridView in my asp page and i want to loop over them by inserting them in list
however this throw an exception on run time
i know that Im missing something

my code is :

 List<object> grdvw;
 protected void Page_Load(object sender, EventArgs e)
    {
        
        
        grdvw.Add(GridView1);
        grdvw.Add(GridView2);
        grdvw.Add(GridView3);
        grdvw.Add(GridView4);
        grdvw.Add(GridView5);
        grdvw.Add(GridView6);
        grdvw.Add(GridView7);
        grdvw.Add(GridView8);
        grdvw.Add(GridView9);
        grdvw.Add(GridView10);

 //counting no of list:
        var waitingDoc = (from wdoc in db.waitings
                          join doc in db.Emplyees on wdoc.DoctorId equals doc.EmpID
                          where wdoc.dismissed != 2
                          select new { doc.EmpName, doc.EmpID }).Distinct();
        int doctors = waitingDoc.Count();

        docCountlbl.Text = doctors.ToString();

        int li = 0;
        if (waitingDoc.Count() > 0)
        {

            foreach (var docdata in waitingDoc)
            {

                //make div and gridview visible

                foreach (Control TempControl in this.Form.Controls)
                {
                    if (TempControl is GridView && TempControl.ID == grdvw[li])
                    {

                        GridView TempGridView = TempControl as GridView;
                        TempGridView.Visible = true;
                    }
                }

                foreach (Control TempControl in this.Form.Controls)
                {
                    if (TempControl.ID == divesion[li])
                    {

                        TempControl.Visible = true;
                    }
                }
                //clear the data
                waiting.Clear();



                //column heades        

                string DocName = (from doctr in db.Emplyees
                                  where doctr.EmpID == docdata.EmpID
                                  select doctr.EmpName).Single();
                waiting.Columns.Add("postion");
                waiting.Columns.Add("Dr " + DocName);
                waiting.Columns.Add("s");

                // get data and index
                var witingList = from wait in db.waitings
                                 join doc in db.Emplyees on wait.DoctorId equals doc.EmpID
                                 join cli in db.Clints on wait.clintID equals cli.ClintID
                                 where wait.dismissed != 2 && doc.EmpID == docdata.EmpID
                                 select new { ClintName = cli.Name, position = wait.dismissed };

                int noFrows = witingList.Count();
                int i = 1;
                foreach (var item in witingList)
                {
                    DataRow lin = waiting.NewRow();
                    lin[2] = i;
                    lin[1] = item.ClintName.ToString();


                    if (item.position == 1)
                    {
                        lin[0] = "Clinic";

                    }

                    if (item.position == 0)
                    {
                        lin[0] = "waiting";

                    }
                    if (item.position == 3)
                    {
                        lin[0] = "finished";

                    }

                    i++;
                    waiting.Rows.Add(lin);
                }



            }


        }
    }
}

when i run it it give me this exception

Object reference not set to an instance of an object. 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 


Line 18:         
Line 19:         
Line 20:         grdvw.Add(GridView1);
Line 21:         grdvw.Add(GridView2);
Line 22:         grdvw.Add(GridView3); 

解决方案

To me it looks your global variable grdvw might not be initialized. In your PageLoad Function you could try something this.

if(grdvw == null)

 {
    grdvw = new List<object>();
 }

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