NeedsDataSource - Persisting DataSource

[Jerry]

I don't want RadGrid "NeedsDataSource" handler to re-query the database every time the event fires, but I do want it to act on its datasource as it is designed to do. I handle database queries in my "Search" button handler where I get a DataTable and the set RadGid's datasource equal to my datatable. Also, to persist my DataTable, I set a Session variable equal to my DataTable. Then, in RadGrid's "NeedDataSource" I set RadGrid's DataSource equal to my Session variable like the following:

   protected void BindDataTable( DataTable dt)
   {
      RadGrid1.DataSource = dt;
      RadGrid1.DataBind();
      RadGrid1.CurrentPageIndex = 1;
     Session["RADGRIDSOURCE"] = dt;
   }

   protected void RadGrid1_NeedDataSource(object sender, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
    {
       RadGrid1.DataSource = Session["RADGRIDSOURCE"];
    }


I am questioning weather this is the best approach or not. Is there a better way?

[Konstantin Dikov]

Hello Jerry,

Since RadGrid provides caching functionality only for the client-side binding, the only possible approach is the one that you have implemented.

Following is a simple example of the same, but accomplished only within the NeedDataSource event handler:

protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
    if (!Page.IsPostBack)
    {
        Session["GridDataTable"] = GetDataTable();
    }

    (sender as RadGrid).DataSource = Session["GridDataTable"];
}

private DataTable GetDataTable()
{
    DataTable table = new DataTable();
    table.Columns.Add("ID", typeof(int));
    table.Columns.Add("FirstName", typeof(string));
    for (int i = 0; i < 55; i++)
    {
        table.Rows.Add(i, "FirstName" + i);
    }

    return table;
}

Please have in mind that with such approach, the data will not be up-to-date.


Regards,
Konstantin Dikov
Telerik

 

 

[Jerry]

I have read that such an approach can cause performance problems for the Web Server because of the amount of Server memory required to store datasets in session variables. Is this true?  

[Konstantin Dikov]

Hello Jerry,

Using the Session object has its downsides, but with your requirement you will have to decide whether to use the Session (or the ViewState) to store your data or to perform a request to the database.

The following article and forum thread could help in your decision:

• Using the Session Object Wisely
• Session Vs ViewState
• Storing datatable in ViewState
  

Hope that helps.
 

Regards,
Konstantin Dikov
Telerik