Objectives

This tutorial demonstrates how to refresh server control programmatically without causing full page postback.

Drag two DropDownList controls into the WebForm and name them ddlMake and ddlModel.
Drag WebFlyPostBackManager from Toolbox into a WebForm page.

In code behind, add the following code.

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using ISNet.WebUI.WebDesktop;

public partial class ProgrammaticallyRefresh : System.Web.UI.Page
{
    WebFlyPostBackListener listener = null;

    protected void Page_Load(object sender, EventArgs e)
    {
        body.Style.Add("overflow", "hidden");
        listener = new WebFlyPostBackListener(this);
    }
}

Add some items to ddlMake.

Add a method to populate data for ddlModel based on the value of ddlMake. Note that you must add WebFlyPostBackMethod() attribute so that the method can be included in the Metadata collection.

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[WebFlyPostBackMethod()]
public void PopulateModel()
{    
   ddlModel.Items.Clear();    
   if (ddlMake.Text != "- Select a Make -")    
   {        
      for (int i = 1; i <= 5; i++)            
         ddlModel.Items.Add(new ListItem(ddlMake.Text + " Model " + i.ToString(), i.ToString()));    
   }    
   ddlMake.SelectedIndex = 1;     

   WebFlyPostBackManager1.ClientAction.UpdateViewState();     
   WebFlyPostBackManager1.ClientAction.RenderControl(ddlModel);
}

Add onchange event for ddlMake to call PopulateModel method from client side using WebFlyPostBackManager.

Script	Copy Code
<script language="javascript"> function PopulateModel() { var fpb = ISGetObject("WebFlyPostBackManager1"); fpb.PopulateModel(); } </script>

Set the following properties of WebFlyPostBackManager.

Properties	Values
ServiceType	WebForm
ServiceUrl	The URL path of the page (in this case, the path is ~/test/ProgrammaticallyRefresh.aspx)
PostInputControls	True
PostViewState	True

Run the page. Select a value from ddlMake and data will be populated in ddlModel without causing full page postback.

Intersoft WebDesktop Documentation
Programmatically refresh server control
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