Imagine the following approach:
- Combobox items are added in the Page_Load event. The items are added from a huge datasource. The code is placed in
if (!Page.IsPostBack)
{
//Initialization code
}
Telerik RadComboBox is in a callback mode - the items are also added in the ItemsRequested event of the combobox.
- The code in the if (!Page.IsPostBack) block is executed upon each postback. This is what makes the combobox performance slow.
Telerik RadComboBox performs a "light" callback to the server - no ViewState information is sent to the server and the Page.IsPostBack property is set to False when the combobox is in a callback mode.
In addition, the Page_Load method is called before the ItemsRequested event. Therefore, all page initialization code is fired, too.
To avoid re-executing of the code in the Page_Load event, you should check for both Page.IsPostBack and RadComboBox.IsCallBack:
Example:
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...
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack && !RadComboBox.IsCallBack)
{
//Initialization code
}
} |