Passing page control from jscript to pagemethod in the codebehind?

Question

Hi, I am looking write a javascript method as such called when a dropdownlist changes value

function GetStuff(sender, destID){

    var dest = document.getElementById(destID);
    this.PageMethods.GetStuffs(sender, dest, null, null);
}

GetStuffs() is in the Codebehind as follows:

[WebMethod]
public static void GetStuffs(object sender, object dest)
{
    DropDownList s = sender as DropDownList;
    DropDownList d = dest as DropDownList;

    d.Items.Add(new ListItem(s.SelectedValue));
}

I have a break point set at the method and alerts in the GetStuff() jscript method fire up until the PageMethod call, at which nothing happens. I have set OnSuccess and OnFailure methods up with alerts and they don't get fired.

Any thoughts? Am I doing something inherently wrong?

Answer 1

Couple of items to note:

• The GetStuffs class is returning void, so OnSuccess or OnFailure will not fire
• Even if you do return something back, the control on the UI will not update because the PageMethod just returns a value to the calling javascript but does not update the UI in anyway
• You will need to handle the OnSuccess event on the client & then update the dropdown on the client
• Any change to the control on the server does not reflect on the client using PageMethods
• The other point to note is that you are passing back an object of the dropdown which is a DOM element & casting it to a Server side control. This is not possible.