Ajax AutoComplete Extender

Ok, step 1:

Make your WebService. In your project, create a folder called Services, (not a necessity, but neat :P) Right click and say Add -> New Web Service. Lets call it WSAutoComplete. Now make it look like this:

namespace Services
{
    /// <summary>
    /// Summary description for WSAutoComplete
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
    [System.Web.Script.Services.ScriptService]
    public class WSAutoComplete : System.Web.Services.WebService
    {
        [WebMethod]
        [ScriptMethod]
        public string[] GetAutoCompleteList(string prefixText, int count)
        {
            return GetResults(prefixText, count);
        }
    }

    private string[] GetResults(prefixText, count)
    {
         //Do your logic here
         //Example
         List<string> items = new List<string>() {"bob", "steve", "jones", "andrew"};
         List<string> result = new List<string();>
         foreach (string s in items)
             if (s.StartsWith(prefixText))
                 result.Add(s);
         return result.ToArray();
    }</string></string></string>

(Ignore this </string></string></string>, I dont know why thats there being generated by the text editor???)

I purposely left out the count for time purposes, you can add that yourself, just limit the amount of results that you return.

Now, on you AutoCompleteExtender control:

<asp:TextBox id="txtMyTextBox" runat="server"></asp:TextBox>
<asp:AutoCompleteExtender TargetControlID="txtMyTextBox" ServicePath="/Services/WSAutoComplete.asmx"CompletionInterval="500" MinimumPrefixLength="2" ServiceMethod="GetResults"
ID="autocomplete" runat="server"></asp:AutoCompleteExtender>

That should work 100%!!! Make sure you set up your service path correctly! Put a break point inside you service method and see if it gets hit! If it doesnt, then there is probably a problem with your ServicePath or ServiceMethod paramter