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c#asp.netautocompleteajaxcontroltoolkit

How can I add selected value in an asp.net ajax toolbox autocomplete to a label?

I have got the Ajax toolkit autocomplete working using the following asp.net and C# code.

<form id="form1" runat="server">
    <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    </asp:ToolkitScriptManager> 
    <div>
        Search our Languages: <asp:TextBox ID="txtLanguage" runat="server"></asp:TextBox>

        <asp:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" 
            TargetControlID="txtLanguage" MinimumPrefixLength="1" 
            ServiceMethod="GetCompletionList" UseContextKey="True">
        </asp:AutoCompleteExtender>
        <br />
        <br />
        <asp:Button ID="btnAddSelected" runat="server" Text="Add to chosen Languages >" 
            onclick="btnAddSelected_Click" />
        <br />
        <br />
        <asp:Label ID="lblSelectedLanguages" runat="server" Text=""></asp:Label>
    </div>
</form>

This is my codebehind C#:

[System.Web.Services.WebMethodAttribute(), System.Web.Script.Services.ScriptMethodAttribute()]
public static string[] GetCompletionList(string prefixText, int count, string contextKey)
{
    // Create array of languages. 
    string[] languages = { "Afrikaans", "Albanian", "Amharic", "Arabic", "Azerbaijani", "Basque", "Belarusian", "Bengali", "Bosnian", "Bulgarian" };

    // Return matching languages. 
    return (from l in languages where l.StartsWith(prefixText, StringComparison.CurrentCultureIgnoreCase) select l).Take(count).ToArray();
}

protected void btnAddSelected_Click(object sender, EventArgs e)
{
    lblSelectedLanguages.Text += txtLanguage.Text += ", ";
}

The selected language is added to the label when the button is clicked, however I would like to remove the button and make the selected item from the autocomplete added to the label automatically, using the partial postback from the Ajax toolkit.

Can someone please advise as to how I can achieve this?

Thanks.

Solution
    1. Handle OnClientItemSelected on the AutoCompleteExtender control to run a javascript function
    2. All the javascript does is simply fire off the TextChanged event when the selection is made (works on both Enter and left click)

    ASPX:

    <head runat="server">
    <title></title>
    <script type="text/javascript">
        function ItemSelected(sender, args) {
            __doPostBack(sender.get_element().name, "");
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
    </asp:ToolkitScriptManager>
    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            Search our Languages:&nbsp;
            <asp:TextBox ID="txtLanguage" autocomplete="off" runat="server" OnTextChanged="TextChanged" />
            <asp:AutoCompleteExtender OnClientItemSelected="ItemSelected" ID="AutoCompleteExtender1"
                runat="server" TargetControlID="txtLanguage" MinimumPrefixLength="1" ServiceMethod="GetCompletionList"
                UseContextKey="True">
            </asp:AutoCompleteExtender>
            <br />
            <asp:Label ID="lblSelectedLanguages" runat="server"></asp:Label>
        </ContentTemplate>
    </asp:UpdatePanel>
    </form>
</body>

    Code behind:

    protected void TextChanged(object sender, EventArgs e)
{
    lblSelectedLanguages.Text += txtLanguage.Text += ", ";
}