DynamicPopulate is a simple extender that replaces the contents of a control with the result of a web service or page method call. The method call returns a string of HTML that is inserted as the children of the target element.

The control above is initialized with this code:

<ajaxToolkit:DynamicPopulateExtender ID="dp" runat="server"
    TargetControlID="Panel1" 
    ClearContentsDuringUpdate="true" 
    PopulateTriggerControlID="Label1" 
    ServiceMethod="GetHtml" 
    UpdatingCssClass="dynamicPopulate_Updating" />

• TargetControlID - The ID of the button or link for this extender to operate on
• ClearContentsDuringUpdate - true (default) to clear the HTML contents of the target element when an update begins
• ServicePath - The URL of the web service to call. Leave this parameter blank and specify a ServiceMethod to call a PageMethod.
• ServiceMethod - The name of the method to call on the page or web service. The signature of this method must match the following:

  [WebMethod]
  string DynamicPopulateMethod(string contextKey){...}

  Note you can replace "DynamicPopulateMethod" with a naming of your choice, but the return type and parameter name and type must exactly match, including case.
• PopulateTriggerControlID - The optional name of a control that, when clicked, triggers the population of the target.
• UpdatingCssClass - The CSS class to apply to the target during asynchronous calls.
• CustomScript - The script to invoke instead of calling a Web or Page method. This script must evaluate to a string value.
• ContextKey - An arbitrary string value to be passed to the web method. For example, if the element to be populated is within a data-bound repeater, this could be the ID of the current row.