Ajax autocomplete extender and get ID of selected item? - asp.net

Question

I am using the autocomplete extender to suggest names when a user types. How to get the select value after the user selects an item? I guess I can use onclientitemselected but I am not familiar on how to write this? I need to populate a textbox based on the selection in the autocompleteextender textbox. Thank you
<asp:TextBox ID="TextBox1" runat="server" Height="27px" Width="570px"></asp:TextBox>
<asp:AutoCompleteExtender ID="AutoCompleteExtender" runat="server"
DelimiterCharacters="" Enabled="True" ServicePath="AutoComplete.asmx"
ServiceMethod="GetCompletionList" TargetControlID="TextBox1"
MinimumPrefixLength="2" UseContextKey="true" ContextKey="StateDropDown"
CompletionListElementID="autocompleteDropDownPanel">
</asp:AutoCompleteExtender>

Answer 1

For this you need to return the list from web service method with ID and Text
Here "lst" is the actual list with data from your data source.
List<string> items = new List<string>(count);
for (int i = 0; i < lst.Count; i++)
{
string str =AjaxControlToolkit.AutoCompleteExtender.CreateAutoCompleteItem(lst[i].Text,Convert.ToString(lst[i].IDValue));
items.Add(str);
}
return items.ToArray();
Then simple javascript
function GetID(source, eventArgs )
{
var HdnKey = eventArgs.get_value();
document.getElementById('<%=hdnID.ClientID %>').value = HdnKey;
}
and dont forget to set the attribute in auto complete extender
OnClientItemSelected="GetID"

Answer 2

The AutoCompleteExtender merely extends the ASP.NET TextBox control, so if you want to know when the text changed, then just raise the TextChanged event on the TextBox control, like this:
Markup:
<asp:TextBox ID="TextBox1" runat="server" Height="27px" Width="570px" OnTextChanged="TextBox1_TextChanged" AutoPostBack="true"></asp:TextBox>
Code-Behind:
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
// Do something here with textbox value
}