Custom DataGrid With Next, Previous, First, Last, and Numeric Paging

Wednesday Jan 31st 2007 by saifi hasan
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Learn how to create a custom DataGrid with previous, next, first, and last paging along with numeric paging.

Introduction

In one of my web projects, the requirement was such that the pager should have numeric paging as well as links for previous, next, first, and last pages. The DataGrid did not directly support this type of layout; that's why I have developed my custom DataGrid that can be used throughout.

Background

The basic idea is very simple: Create a custom control that is inherited by DataGrid and overrides the ItemCreated event. Here, you have to understand how DataGrid renders controls for Pager. The DataGrid renders controls like this (LinkButton or label) (Literal control) (LinkButton or label) ... and so on. Literals are used to put space between controls and Labels are used to show disabled pager links.

You can calculate the total pages from the items in the pager cell by using this formula:

TotalPages = (e.Item.Cells[0].Controls.Count /2) +1

This count is useful for assigning the command argument for ImageButton for the last page. The onItemCreated event is written below.

Using the Code

Just add the MycustomDG.dll in the VS .NET toolbar or add a reference to MycustomDG.dll. Assign the following properties:

  • ShowPreviousAndNextImage
  • ShowFirstAndLastImage
  • ImageFirst
  • ImageLast
  • ImagePrevious
  • ImageNext

Code for OnItemCreated

protected override void OnItemCreated(DataGridItemEventArgs e)
{
   if(e.Item.ItemType == ListItemType.Pager)
   {
      int _TotalCount  = e.Item.Cells[0].Controls.Count;
      int _TotalPagers = (_TotalCount/ 2) +1;
      int _CurrentPage = this.CurrentPageIndex;
      if(_TotalCount > 1)
      {
         LinkButton btnPrev  = new LinkButton();
         LinkButton btnNext  = new LinkButton();
         LinkButton btnFirst = new LinkButton();
         LinkButton btnLast  = new LinkButton();

         if(_Show_Prev_Next_Image)
         {
            #region Next & previous
            if(_CurrentPage +1 <= _TotalPagers )
            {    // Enable Next
               string sImgNext ="<img alt='Next' border='0'
                                 src='"+ _ImgNext+"'>";
               btnNext.Text = sImgNext;
               btnNext.CommandArgument = (_CurrentPage+2).ToString();
               btnNext.CommandName = "Page";
               btnNext.Enabled = true;
            }
            else
            {    // disable next
               string sImgNext ="<img alt='Next' border='0'
                                 src='"+ _ImgNext+"'>";
               btnNext.Text = sImgNext;
               btnNext.Enabled = false;
            }

            if(_CurrentPage > 0)
            {    // enable Previous
               string sImgPre ="<img alt='Previous' border='0'
                                src='"+ _ImgPrev+"'>";
               btnPrev.Text = sImgPre;
               btnPrev.CommandName = "Page";
               btnPrev.CommandArgument = (_CurrentPage).ToString();
               btnPrev.Enabled = true;
            }
            else
            {    // disable previous
               string sImgPre ="<img alt='Previous' border='0'
                                src='"+ _ImgPrev+"'>";
               btnPrev.Text = sImgPre;
               btnPrev.Enabled = false;
            }
            #endregion
         }


         if(_Show_First_Last_Image)
         {
            #region First & last
            if(e.Item.Cells[0].Controls[_TotalCount -1].GetType() !=
               typeof(System.Web.UI.WebControls.Label))
            {
               string sImgNext ="<img alt='Last' border='0'
                                 src='"+ _ImageLast+"'>";
               btnLast.CommandArgument = _TotalPagers.ToString();
               btnLast.CommandName = "Page";
               btnLast.Text = sImgNext;
               btnLast.Enabled = true;
            }
            else
            {
               string sImgNext ="<img alt='Last' border='0'
                                 src='"+ _ImageLast+"'>";
               btnLast.Text = sImgNext;
               btnLast.Enabled = false;
            }


            if(e.Item.Cells[0].Controls[0].GetType() !=
               typeof(System.Web.UI.WebControls.Label))
            {
               string sImgPre ="<img alt='First' border='0'
                                src='"+ _ImageFirst+"'>";
               btnFirst.CommandArgument = "1";
               btnFirst.CommandName = "Page";
               btnFirst.Text = sImgPre;
               btnFirst.Enabled = true;
            }
            else
            {
               string sImgPre ="<img alt='First' border='0'
                                src='"+ _ImageFirst+"'>";
               btnFirst.Text = sImgPre;
               btnFirst.Enabled = false;
            }
            #endregion
         }


         e.Item.Cells[0].Controls.AddAt(0,btnPrev);
         e.Item.Cells[0].Controls.AddAt(e.Item.Cells[0].Controls.Count,
                                        btnNext);
         // Add These 2 Images at the First and last Position
         e.Item.Cells[0].Controls.AddAt(0,btnFirst);
         e.Item.Cells[0].Controls.AddAt(e.Item.Cells[0].Controls.Count,
                                        btnLast);
      }
   }
   base.OnItemCreated (e);
}
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