Objectives

This tutorial demonstrates how to convert standard controls to use callback.

Drag two DropDownList controls into the WebForm and name them ddlMake and ddlModel.
Drag two CheckBoxList control into the WebForm.
Drag 4 Button controls into the WebForm.
Add some items to ddlMake.
Set AutoPostBack property of ddlMake to True.

Specify a method for SelectedIndexChanged server side events and add the following code.

Copy Code

protected void ddlMake_SelectedIndexChanged(object sender, EventArgs e)
{    
   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;
}

Add button's OnClick event to add and remove items between CheckBoxLists.

Copy Code

protected void Button3_Click(object sender, EventArgs e)
{    
   // move to right    
   bool hasSelection = false;    
   for (int i = 0; i < CheckBoxList1.Items.Count; i++)    
   {        
      ListItem item = CheckBoxList1.Items[i];

      if (item.Selected)        
      {            
         hasSelection = true;            
         MoveItem(item, CheckBoxList1, CheckBoxList2);            
         i--;        
      }    
  }
}

protected void Button1_Click(object sender, EventArgs e)
{    
   // move all to left    
   for (int i = 0; i < CheckBoxList2.Items.Count; i++)    
   {        
      ListItem item = CheckBoxList2.Items[i];
      MoveItem(item, CheckBoxList2, CheckBoxList1);        
      i--;    
   }
}

protected void Button2_Click(object sender, EventArgs e)
{    
   // move to left    
   bool hasSelection = false;
    
   for (int i = 0; i < CheckBoxList2.Items.Count; i++)    
   {        
      ListItem item = CheckBoxList2.Items[i];
      
      if (item.Selected)        
      {            
         hasSelection = true;            
         MoveItem(item, CheckBoxList2, CheckBoxList1);            
         i--;        
      }    
   }
}

protected void Button4_Click(object sender, EventArgs e)
{    
   // move all to right    
   for (int i = 0; i < CheckBoxList1.Items.Count; i++)    
   {        
      ListItem item = CheckBoxList1.Items[i];
      MoveItem(item, CheckBoxList1, CheckBoxList2);        
      i--;    
   }
}

private void MoveItem(ListItem item, CheckBoxList from, CheckBoxList to)
{    
   to.Items.Add(new ListItem(item.Text));    
   item.Selected = false;    
   from.Items.Remove(item);    
}

Run the page. Selecting a value from ddlMake to populate data in ddlModel will cause full page postback.

Clicking the button to remove items between CheckBoxLists will also cause full page postback.
Drag WebFlyPostBackManager from Toolbox into a WebForm page.

In code behind, add the following code.

Copy Code

using ISNet.WebUI.WebDesktop;

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

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

Set the following properties of WebFlyPostBackManager.

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

Add the following code in MoveItem method so that removed items in CheckBoxList are considered as Dirty in view state.

C#	Copy Code
WebFlyPostBackManager1.ClientAction.MarkDirty(from);

Run the page. Selecting a value from ddlMake will populate data in ddlModel without causing full page postback.

Clicking the button to remove items between CheckBoxLists will not cause full page postback.

Intersoft WebDesktop Documentation
Converting standard controls to use callback
Send Feedback