How to bind dropdown selected value while editiing in gridview

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C#

Hello,
I am generating dynamic textboxes and dropdownlist and bind it in gridview by maintaining its viewstate. After clicking save button, it redirects to another page where i have given option of edit. On clicking edit button, user redirects to edit page where I generate dynamic textboxes and dropdownlist but unable to bind dropdown selected value.

Here is my code:

static int Empid;
static int m;
string drop;
protected void Page_Load(object sender, EventArgs e)
{
   if (Request.QueryString["edit"] != null)
   {
      if (!IsPostBack)
      {
         SetInitialRow();
      }
   }
}

private void SetInitialRow()
{
   int k;
   input.Storeid = int.Parse(Request.QueryString["edit"]);
   purchaseoutput = purchaseorderedit.Execute(input);
   k = purchaseoutput.Supplierid;
   datalist_activestore.DataSource = purchaseoutput.DtDepartment;
   datalist_activestore.DataBind();

   DataTable dt = new DataTable();
   DataRow dr = null;
   dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
   dt.Columns.Add(new DataColumn("Column1", typeof(string)));
   dt.Columns.Add(new DataColumn("Column2", typeof(string)));
   dt.Columns.Add(new DataColumn("Column3", typeof(string)));
   dt.Columns.Add(new DataColumn("Column4", typeof(string)));
   dt.Columns.Add(new DataColumn("Column5", typeof(string)));

   int i = 0;

   foreach (DataListItem li in datalist_activestore.Items)
   {
      dr = dt.NewRow();
      dr["RowNumber"] = i + 1;
      Label item_name = (Label)li.FindControl("lbl_itemname");
      DropDownList drp = (DropDownList)li.FindControl("dropdownlist_storeitem");
      // drp.SelectedItem.Text = item_name.Text.ToString();

      Label quantity = (Label)li.FindControl("lbl_quantity");
      Label discount = (Label)li.FindControl("lbl_discount");
      Label tax = (Label)li.FindControl("lbl_tax");

      Label price = (Label)li.FindControl("lbl_price");

      dt.Rows.Add(dr);

      ViewState["CurrentTable"] = dt;

      Gridview1.DataSource = dt;
      Gridview1.DataBind();

      TextBox box2 = (TextBox)Gridview1.Rows[i].Cells[2].FindControl("TextBox2");
      TextBox box3 = (TextBox)Gridview1.Rows[i].Cells[3].FindControl("TextBox3");
      TextBox box4 = (TextBox)Gridview1.Rows[i].Cells[4].FindControl("TextBox4");
      TextBox box5 = (TextBox)Gridview1.Rows[i].Cells[4].FindControl("TextBox5");
             
      box2.Text = quantity.Text;
      // dr["Column2"] = box2.Text;
      box3.Text = discount.Text;
      box4.Text = tax.Text;
      box5.Text = price.Text;
      // ddl.Text = item_name.Text;
      purchaseoutput = purchaseoredr.Execute(input);

      DropDownList ddl = (DropDownList)Gridview1.Rows[i].Cells[1].FindControl("DROPDOWNLIST1");

      ddl.DataSource = getitemoutput.DtCategory;
      ddl.DataTextField = "item_name";
      ddl.DataValueField = "store_item_id";
      ddl.DataBind();
      ddl.Items.Insert(0, item_name.Text);
      drop = item_name.Text;

      m = i;
      setrow();
      i++;
   }
}
      
private void setrow()
{
   if (ViewState["CurrentTable"] != null)
   {
      DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
      DataRow drCurrentRow = null;

      if (dtCurrentTable.Rows.Count > 0)
      {
         DropDownList box1 = (DropDownList)Gridview1.Rows[m].Cells[1].FindControl("DROPDOWNLIST1");
         // box1.SelectedItem.Text = drop;
         TextBox box2 = (TextBox)Gridview1.Rows[m].Cells[2].FindControl("TextBox2");
         TextBox box3 = (TextBox)Gridview1.Rows[m].Cells[3].FindControl("TextBox3");
         TextBox box4 = (TextBox)Gridview1.Rows[m].Cells[4].FindControl("TextBox4");
         TextBox box5 = (TextBox)Gridview1.Rows[m].Cells[4].FindControl("TextBox5");

         m = m + 1;

         dtCurrentTable.Rows[m - 1]["Column1"] = box1.Text;
         dtCurrentTable.Rows[m - 1]["Column2"] = box2.Text;
         dtCurrentTable.Rows[m - 1]["Column3"] = box3.Text;
         dtCurrentTable.Rows[m - 1]["Column4"] = box4.Text;
         dtCurrentTable.Rows[m - 1]["Column5"] = box5.Text;
      }

      ViewState["CurrentTable"] = dtCurrentTable;

      Gridview1.DataSource = dtCurrentTable;
      Gridview1.DataBind();
   }
   else
   {
      Response.Write("ViewState is null");
   }

   //Set Previous Data on Postbacks
   setdata();
}

private void setdata()
{
   try{
      purchaseoutput = purchaseoredr.Execute(input);

      int rowIndex = 0;
      if (ViewState["CurrentTable"] != null)
      {
         DataTable dt = (DataTable)ViewState["CurrentTable"];
         if (dt.Rows.Count > 0)
         {
            for (int i = 0; i < dt.Rows.Count; i++)
            {
               DropDownList box1 = (DropDownList)Gridview1.Rows[rowIndex].Cells[1].FindControl("ddoffence");
               box1.DataSource = getitemoutput.DtCategory;
               box1.DataTextField = "item_name";
               box1.DataValueField = "store_item_id";
               box1.DataBind();

               box1.Items.Insert(0, "Select store");
                   
               // box1.Items.Insert(0, drop);
               // SetInitialRow();
               // box1.SelectedItem.Text = drop;
               TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
               TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
               TextBox box4 = (TextBox)Gridview1.Rows[rowIndex].Cells[4].FindControl("TextBox4");
               TextBox box5 = (TextBox)Gridview1.Rows[rowIndex].Cells[4].FindControl("TextBox5");

               box1.Text = dt.Rows[i]["Column1"].ToString();
               box2.Text = dt.Rows[i]["Column2"].ToString();
               box3.Text = dt.Rows[i]["Column3"].ToString();
               box4.Text = dt.Rows[i]["Column4"].ToString();
               box5.Text = dt.Rows[i]["Column5"].ToString();
                 
               rowIndex++;
            }
         }
     }
  }
  catch (Exception ex)
  {
     if (ex.Message.ToString() == "Thread was being aborted.")
     {
         // nothing 
      }
      else
      {
         #region for exception handling
         string logMessage = "\n\n";
         logMessage += "Error time: " + DateTime.Now.ToString() + "\n";
         logMessage += "Error Page: " + HttpContext.Current.Request.Url.ToString() + "\n";
         logMessage += "Error method: " + "setdata()" + "\n";
         logMessage += "Error Message: " + ex.Message.ToString() + "\n";
         logMessage += "\n\n";
         File.AppendAllText(Server.MapPath("~/Admin/ErrorHandling/Errorfile.txt"), logMessage);

         #endregion
         #region  send it to message
         Exceptionhandlingmail usertomail = new Exceptionhandlingmail();
         UserMailInput inputmail = new UserMailInput();
         inputmail.Exception = logMessage;
         usertomail.Exceptionhandling(inputmail);
         Response.Redirect("~/Error.aspx");
         #endregion
      }
   }
}


private void SetPreviousData()
{
   int rowIndex = 0;
   if (ViewState["CurrentTable"] != null)
   {
      DataTable dt = (DataTable)ViewState["CurrentTable"];
      if (dt.Rows.Count > 0)
      {
         for (int i = 0; i < dt.Rows.Count; i++)
         {
            DropDownList box1 = (DropDownList)Gridview1.Rows[rowIndex].Cells[1].FindControl("DROPDOWNLIST1");
            box1.DataSource = getitemoutput.DtCategory;
            box1.DataTextField = "item_name";
            box1.DataValueField = "store_item_id";
            box1.DataBind();
            box1.Items.Insert(0, "Select store");
            TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
            TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
            TextBox box4 = (TextBox)Gridview1.Rows[rowIndex].Cells[4].FindControl("TextBox4");
            TextBox box5 = (TextBox)Gridview1.Rows[rowIndex].Cells[4].FindControl("TextBox5");

            box1.Text = dt.Rows[i]["Column1"].ToString();
            box2.Text = dt.Rows[i]["Column2"].ToString();
            box3.Text = dt.Rows[i]["Column3"].ToString();
            box4.Text = dt.Rows[i]["Column4"].ToString();
            box5.Text = dt.Rows[i]["Column5"].ToString();

            rowIndex++;
         }
      }
   }
}

[edit]Code block added and indexation changed to improve readability[/edit]