Import Excel to Json format on ASP.NET

Question

I need to ask about import excel sheet question with child-parent relationship.

below i have a sample table

 

 

output i want to like that

[{"Code":"888800","Title":"Category","Value":"123","Children":[]}, 
 {"Code":"100000","Title":"Category1","Value":"123","Children": 
   [ 
      {"Code":"120000","Title":"SubCategory","Value":"123","Children":[]}, 
      {"Code":"352000","Title":"SubCategory2","Value":"123","Children":[]}, 
      {"Code":"200000","Title":"SubCategory3","Value":"123","Children":[]}, ]}, 
 {"Code":"212101","Title":"Category3","Value":"123","Children": 
   [ 
      {"Code":"213100","Title":"SubCategory4","Value":"123","Children":[]}, 
      {"Code":"213200","Title":"SubCategory4","Value":"123","Children":[]} 
   ]} 
]

---

below I have a my code, but I don't know where is my wrong point. When I'm creating Json Serialization value and children part not correctly

int sheetname = 0;
   class Position
   {
       public Position()
       {
           this.Children = new List<Position>();
       }

       public string Code { get; set; }
       public string Title { get; set; }
       public string Value { get; set; }

       public List<Position> Children { get; set; }
   }

   Position Parsing(string value)
   {
       string pattern = "\\((?<Code>[\\w]+)\\)(?<Title>.+)";
       var regex = new Regex(pattern);
       var match = regex.Match(value);

       if (match.Success)
       {
           return new Position()
           {
               Code = match.Groups["Code"].Value,
               Title = match.Groups["Title"].Value,
               Value = match.Groups["Value"].Value
           };
       }
       else
       {
           return null;
       }
   }
   protected void Button1_Click(object sender, EventArgs e)
   {
       string sSourceConstr = "";
       string fileName = Path.GetFileName(fuExcel.PostedFile.FileName);

       if (fuExcel.FileName == string.Empty)
       {
           JSBuilder.AlertMessage(this, "ERROR");
       }

       string fileExtension = Path.GetExtension(fuExcel.PostedFile.FileName);
       string fileLocation = Server.MapPath("~/" + fileName);
       fuExcel.SaveAs(fileLocation);


       if (fuExcel.HasFile)
       {
           if (fileExtension == ".xls")
           {
               sSourceConstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
           }
           else if (fileExtension == ".xlsx")
           {
               sSourceConstr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
           }
           try
           {
               IWorkbook workbook = default(IWorkbook);
               using (FileStream file = new FileStream(fileLocation, FileMode.Open))
               {

                   workbook = WorkbookFactory.Create(file);

                   List<string> items = new List<string>();

                   Position posnTop = null;
                   List<Position> posnList = new List<Position>();
                   ISheet sheet = workbook.GetSheetAt(0);
                   for (int row = 1; row <= sheet.LastRowNum; row++)
                   {
                       if (sheet.GetRow(row) != null)
                       {
                           DataTable dt = new DataTable();

                           IRow excelRow = default(IRow);
                           excelRow = sheet.GetRow(1);
                           for (int Cel = 1; Cel <= excelRow.LastCellNum - 1; Cel++)
                           {

                               string industry = sheet.GetRow(1).GetCell(Cel).ToString();
                               string IndustryCode = sheet.GetRow(2).GetCell(Cel).ToString();

                               for (int k = 4; k <= sheet.LastRowNum; k++)
                               {
                                   items.AddRange(sheet.GetRow(k).GetCell(Cel - 1).ToString().Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries));

                                   foreach (var item in items)
                                   {
                                       if (!string.IsNullOrEmpty(item) && item.Length > 1)
                                       {
                                           if ("\t".Equals(item.Substring(0, 1)))
                                           {
                                               //child
                                               var posn = this.Parsing(item.Trim());
                                               if (posn != null)
                                               {
                                                   posnTop.Children.Add(posn);
                                               }
                                           }
                                           else
                                           {
                                               var posn = this.Parsing(item);
                                               if (posn != null)
                                               {
                                                   posnTop = posn;
                                                   posnList.Add(posn);
                                               }
                                           }


                                             if (sheet.GetRow(k).GetCell(Cel) != null)
                                           {
                                               string value = sheet.GetRow(k).GetCell(Cel).ToString();
                                           }
                                       }
                                   }


                               }
                           }
                           TextBox txtMsg = new TextBox();
                           this.txtMsg.Text = Newtonsoft.Json.JsonConvert.SerializeObject(posnList);
                           #region information Import to SQLSERVER
                           ////////////////////
                           //import sql part//
                           ////////////////////
                           #endregion
                       }
                       else
                       {
                           JSBuilder.AlertMessage(this, true, "import succesfull");
                       }
                   }
               }
           }
           catch (Exception ex)
           {
               Response.Write(ex);
           }
       }
   }