Bunjeeb's Blog

After a couple of months without touching anything related to WEB. I’m doing some refreshment by creating Web Diagram Tool using jQuery “Something like Visio on WEB”.

Also my brother asked me to help to him to do a paging using AJAX.

I found some articles that used Update Panel …Yuk!!! .. Come-on people! are you still use it!! Update Panel could be useful sometimes. But its not a full AJAX. It will create a request for the whole page and when response comes back; It will refresh the part which in update panel.

I did something deferent and better. Its not new at all. Actually I worked on this task before a couple of years; I’m doing some refreshment, my brother just triggered me when he ask.

Simply, I loaded the Usercontrol  dynamically. and the Usercontrol contains anything you want (in my case it’s a GridView). Tada! pretty easy.

to load controls dynamically use this static method. I you want to use it; just modify it by adding your control and set your own properties.

private static String GetGridControlContent(String controlLocation,

 int pgIndex, int pgSize)
 {
   var page = new Page();

   var userControl = (MyGridView)page.LoadControl(controlLocation);

   if (pgIndex < 0)
         pgIndex = 0;

   userControl.PageSize = pgSize;
   userControl.PageIndex = pgIndex;

   page.Controls.Add(userControl);

   String htmlContent = "";

   using (var textWriter = new StringWriter())
   {
    HttpContext.Current.Server.Execute(page, textWriter, false);
    htmlContent = textWriter.ToString();
   }
   return htmlContent;
 }

As you see above; you can pass any parameter to the Usercontrol by creating a properties in that user control. For me I created PageSize & PageIndex properties.

You can wrap this method in a web method to call it from Javascript.

[WebMethod]
public static string AjaxGetGridCtrl(int pgIndex, int pgSize)
{
     return GetGridControlContent("~/MyGridView.ascx", pgIndex, 

                                  pgSize);
}

So you can load you control using script mnager or using jQuery AJAX library. I used the 2nd choice

$.ajax({
    type: 'POST',
    url: 'MyDefault.aspx/AjaxGetGridCtrl',
    contentType: "application/json; charset=utf-8",
    dataType: 'json',
    success: function (data) {
       $('#mainDiv').html(data.d);
    },
    data: "{pgIndex:'" + pgIndex + "', pgSize:'" + pgSize + "'}"
 });

jQuery AJAX is really nice. Let’s talk more about the options above.

type: you choose you either GET, or POST options.

url: I request this URL using POST.

contentType: used when you want to send data to the server (data is the last option). is this case the data will be sent in JSON format with UTF-8 Encoding.

dataType: The type of data that you’re expecting back from the server.

success: response will be handled here; if request succeeded.

I n this example; the HTML result will be rendered in mainDiv element.

data: parameters will be sent to the web method here.

Current Page Index and Page Size are stored in a Hidden Fields. And when user clicked on Next button; the value will be added by 1. And the AJAX call started by sending the new PageIndex.

function FillGrid(flag) {

 var pgIndex = 0;
 var pgCurrentIndex = $('#txtPgIndex').attr('value');
 var pgSize = $('#txtPgSize').attr('value');

 switch (flag) {
      case 'prev':
          pgIndex = parseInt(pgCurrentIndex) - 1;
          break;
      case 'next':
          pgIndex = parseInt(pgCurrentIndex) + 1;
                    break;
            }

            $('#txtPgIndex').attr('value',pgIndex);

      $.ajax({
           type: 'POST',
           url: 'MyDefault.aspx/AjaxGetGridCtrl',
           contentType: "application/json; charset=utf-8",
           dataType: 'json',
           success: function (data) {
               $('#mainDiv').html(data.d);
           },
           data: "{pgIndex:'" + pgIndex + "', pgSize:'" + pgSize + "'}"
       });
    }

Calling GetGridControlContent will cause a crahs at this line

HttpContext.Current.Server.Execute(page, textWriter, false);

To avoid this crash; all you need to do is to add

a [run at server form tag] to your Usercontrol

<%@ Control Language="C#" AutoEventWireup="true" 

    CodeBehind="MyGridView.ascx.cs" 

    Inherits="test.MyGridView" %>

<form id="form1" runat="server">

<asp:GridView ID="gv" runat="server" AllowPaging="true" 

              AutoGenerateColumns="False">
    <Columns>
        <asp:BoundField DataField="ID" 

               HeaderText="First Name" Visible="false" />
        <asp:BoundField DataField="FirstName" 

               HeaderText="First Name" />
        <asp:BoundField DataField="LastName"

               HeaderText="Last Name" />
        <asp:BoundField DataField="Mobile" 

               HeaderText="Mobile" />
        <asp:BoundField DataField="EmpSalary" 

               HeaderText="Salary" />
        <asp:BoundField DataField="HiringDate" 

               HeaderText="Hiring Date" />
        <asp:BoundField DataField="DOB" 

               HeaderText="Date of Birth" />
    </Columns>
</asp:GridView>
<div id="pgingFooter">
    <a href="javascript:void(0);" id="prev">Previous</a> 

        &nbsp;|&nbsp; <a href="javascript:void(0);"
        id="next">Next</a>
</div>

</form>

And there is no magical things in the code behind for this user control, Just fill your GridView Control according to PageIndex & PageSize properties.

public partial class MyGridView : System.Web.UI.UserControl
    {
        private List<Employee> lstEmployees;

        public int PageSize { get; set; }
        public int PageIndex { get; set; }

        protected void Page_Load(object sender, EventArgs e)
        {
            lstEmployees = new List<Employee>();

            FillList();
            lstEmployees = 

                       lstEmployees.Skip(this.PageIndex * this.PageSize)

                                   .Take(this.PageSize).ToList();

            gv.DataSource = lstEmployees;
            gv.DataBind();
        }

        private void FillList()
        {
            for (int j = 1; j <= 100; j++)
            {
                lstEmployees.Add(new Employee { 

                     ID = j, FirstName = "First" + j, 

                     LastName = "Last" + j, 

                     Mobile = "+932 55 1212" + j, 

                     EmpSalary = j * 100, 

                     DOB = "12/12/1990", 

                     iringDate = "12/12/2010" });
            }
        }
    }

You can download the sample from here