First of all you need to create an "ASP.NET Empty Web Site". Then use the following procedure.

Step 1

Create a ConvertDataTableToJson class in the App_Code folder and provide the following:

  1. Convert DataTable To JSON String.
  3. using System.Data
  4. using System.Text;
  5. public class ConvertDatatableToJson
  6. {
  7. public string DataTableToJson(DataTable dt)
  8. {
  9. DataSet ds = new DataSet();
  10. ds.Merge(dt);
  11. StringBuilder JsonStr = new StringBuilder();
  12. if (ds != null && ds.Tables[0].Rows.Count > 0)
  13. {
  14. JsonStr.Append("[");
  15. for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
  16. {
  17. JsonStr.Append("{");
  18. for (int j = 0; j < ds.Tables[0].Columns.Count; j++)
  19. {
  20. if (j < ds.Tables[0].Columns.Count - 1)
  21. {
  22. JsonStr.Append("\"" + ds.Tables[0].Columns[j].ColumnName.ToString() + "\":" + "\"" + ds.Tables[0].Rows[i][j].ToString() + "\",");
  23. }
  24. else if (j == ds.Tables[0].Columns.Count - 1)
  25. {
  26. JsonStr.Append("\"" + ds.Tables[0].Columns[j].ColumnName.ToString() + "\":" + "\"" + ds.Tables[0].Rows[i][j].ToString() + "\"");
  27. }
  28. }
  29. if (i == ds.Tables[0].Rows.Count - 1)
  30. {
  31. JsonStr.Append("}");
  32. }
  33. else
  34. {
  35. JsonStr.Append("},");
  36. }
  37. }
  38. JsonStr.Append("]");
  39. return JsonStr.ToString();
  40. }
  41. else
  42. {
  43. return null;
  44. }
  45. }
Step 2

Insert the grid view control into the Default.aspx page then write the following design code:

  1. <asp:GridView ID="ui_grdVw_EmployeeDetail" runat="server" Width="50%" AutoGenerateColumns="false" HeaderStyle-CssClass="pageheading">
  2. <Columns>
  3. <asp:TemplateField HeaderText="S.NO">
  4. <ItemTemplate>
  5. <%#Container.DataItemIndex+1 %>
  6. </ItemTemplate>
  7. </asp:TemplateField>
  8. <asp:TemplateField HeaderText="Employee ID">
  9. <ItemTemplate>
  10. <asp:Label ID="ui_lbl_EmployeeID" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Emp_id") %>'></asp:Label>
  11. </ItemTemplate>
  12. </asp:TemplateField>
  13. <asp:TemplateField HeaderText="Employee Name">
  14. <ItemTemplate>
  15. <asp:Label ID="ui_lbl_EmployeeName" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Emp_Name") %>'></asp:Label>
  16. </ItemTemplate>
  17. </asp:TemplateField>
  18. <asp:TemplateField HeaderText="Employee Post">
  19. <ItemTemplate>
  20. <asp:Label ID="ui_lbl_EmpJob" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Emp_job") %>'></asp:Label>
  21. </ItemTemplate>
  22. </asp:TemplateField>
  23. <asp:TemplateField HeaderText="Department">
  24. <ItemTemplate>
  25. <asp:Label ID="ui_lbl_Department" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "Emp_Dep") %>'></asp:Label>
  26. </ItemTemplate>
  27. </asp:TemplateField>
  28. </Columns>
  29. </asp:GridView>
  30. <br />
  31. <asp:Button ID="ui_btn_Convert1" runat="server" Text="Manually Convert To Json" OnClick="ui_btn_Convert1_Click" /><br /><br /><br />
  32. <asp:Label ID="ui_lbl_JsonString1" runat="server"></asp:Label>
Step 3

Now, open the Deafult.asps.cs then write the following code:

  1. using System;
  2. using System.Data;
  4. public partial class _Default : System.Web.UI.Page
  5. {
  6. #region Global Variable
  7. DataTable dt;
  8. ConvertDatatableToJson dtJ;
  9. string JsonString = string.Empty;
  10. #endregion
  12. protected void Page_Load(object sender, EventArgs e)
  13. {
  14. if (!IsPostBack)
  15. {
  16. ui_grdvw_EmployeeDetail_Bind();
  17. }
  18. }
  20. protected void ui_grdvw_EmployeeDetail_Bind()
  21. {
  22. dt = new DataTable();
  23. EmployeeRecord employeeRecord = new EmployeeRecord();
  24. dt = employeeRecord.EmpRecord();
  25. ViewState["dt"] = dt;
  26. ui_grdVw_EmployeeDetail.DataSource = dt;
  27. ui_grdVw_EmployeeDetail.DataBind();
  28. }
  30. protected void ui_btn_Convert1_Click(object sender, EventArgs e)
  31. {
  32. dtJ = new ConvertDatatableToJson();
  33. JsonString = dtJ.DataTableToJson((DataTable)ViewState["dt"]);
  34. ui_lbl_JsonString1.Text = JsonString;
  35. }
  36. }

Step 4

Press F5, run the project.

default page

Now, convert the DataTable to a JSON string using the newtonsoft DLL.

Step 1

Download the Newtonsoft DLL and move it to the ASP.Net project's bin folder.

Step 2
Then, insert a button and label UI Control in the Deafult.aspx page as in the following:
  1. <asp:Button ID="iu_btn_Convert2" runat="server" Text="Newtonsoft Convert To Json" OnClick="iu_btn_Convert2_Click" />
  2. <br />
  3. <br />
  4. <asp:Label ID="ui_lbl_JsonString2" runat="server"></asp:Label>
Step 3
Now, write the following code in Default.aspx.cs:

using this namespace.
  1. using Newtonsoft.Json;
And then:
  1. protected void iu_btn_Convert2_Click(object sender, EventArgs e)
  2. {
  3. dt = (DataTable)ViewState["dt"];
  4. JsonString = JsonConvert.SerializeObject((DataTable)ViewState["dt"]);
  5. ui_lbl_JsonString2.Text = JsonString;
  6. }
Now, run the project and click on the Newtonsoft Convert to JSON.

converted json

In the preceding code, I convert the DataTable to a JSON String.

I have attached the sample project for this, download and see how it works.

Thank you.