title: AJAX C# AutoCompleteExtender contextKey
body: <p>How do you dynamically pass parameter/control to contextKey?</p>
  
  <pre><code>&lt;asp:TextBox ID="tbA" runat="server" autocomplete="off"&gt;&lt;/asp:TextBox&gt; 
  &lt;asp:TextBox ID="tbB" runat="server"&gt;hello&lt;/asp:TextBox&gt; 
  &lt;asp:TextBox ID="tbC" runat="server"&gt;world&lt;/asp:TextBox&gt;
  
  &lt;cc1:AutoCompleteExtender ID="aceListA" ServiceMethod="myListServiceA" ServicePath="WebService.asmx" TargetControlID="tbA" runat="server" EnableCaching="true" UseContextKey="true"&gt; &lt;/cc1:AutoCompleteExtender&gt;
  
    [WebMethod]
     public string[] myListServiceA(string prefixText, int count, string contextKey)
  </code></pre>
  
  <p>Because I want to check tbB, tbC at Web Service level.
  I've read this <a href="http://www.aspdotnetcodes.com/AutoComplete_Textbox_Addtional_Parameters.aspx&quot;article&quot;" rel="nofollow noreferrer">article</a> like 5 times, but still doesn't make a sense out of it, per half missing complete codes.</p>