Ajax AutoComplete Extender with contextKey

Question

Aspx code:

<script type ="text/javascript">
    function setContextKey() {
        find('AutoCompExt2').set_contextKey($get("%=TxtSyllabus.ClientID%>").value)
        alert(("<%=TxtSyllabus.ClientID %>").value)
        }
</script>
<asp:TextBox ID = "TxtSem" runat = "server" Width = "200px" onkeyup="setContextKey()"></asp:TextBox>
<asp:AutoCompleteExtender ID = "AutoCompExt2" runat = "server" MinimumPrefixLength="2" CompletionInterval="100" FirstRowSelected = "false"
        TargetControlID= "TxtSem" EnableCaching = "false" CompletionSetCount = "10" ServiceMethod = "SearchSem" UseContextKey= "true" ></asp:AutoCompleteExtender>`

VB Code:

<System.Web.Script.Services.ScriptMethod(), System.Web.Services.WebMethod()> _
Public Shared Function SearchSem(ByVal prefixText As String, ByVal count As Integer, ByVal contextKey As String) As List(Of String)
    Try
        Dim cnn As New SqlConnection
        Dim cmd As New SqlCommand
        Dim ds As New Data.DataSet
        Dim SyllabusName = Mid(contextKey, 1, Len(contextKey) - 4)
        Dim Year = Mid(contextKey, Len(contextKey) - 4, Len(contextKey))


        cnn.ConnectionString = ConfigurationManager.ConnectionStrings("excelconn").ToString()
        cmd.CommandText = "Select Semester From MastLookup where SyllabusName='" & SyllabusName & "' And SyllabusYear='" & Year & "' And Semester=@SearchText + '%'"
        cmd.Parameters.AddWithValue("SearchText", prefixText)
        cmd.CommandType = Data.CommandType.Text
        cmd.Connection = cnn
        cnn.Open()

        Dim Syllabus As List(Of String) = New List(Of String)
        Dim sdr As SqlDataReader = cmd.ExecuteReader
        While sdr.Read
            Syllabus.Add(sdr("Semester").ToString)
        End While
        cnn.Close()
        Return Syllabus
        cnn.Close()
    Catch ex As Exception

    End Try
End Function`

Error: I am getting null value of ContextKey and even Alertbox is not appeared.

Answer 1

You should be finding the AutoCompleteExtender by its BehaviorID, not ID (BehaviorID extends functionality of the DOM element returned, i.e. providing the set_contextKey function). You're also missing a $ in front of the find function.

<script type="text/javascript">
    function setContextKey() {
        $find('AutoCompBehavior2').set_contextKey($get("%=TxtSyllabus.ClientID%>").value)
        alert(("<%=TxtSyllabus.ClientID %>").value)
    }
</script>

<asp:TextBox ID="TxtSem" runat="server" Width="200px" onkeyup="setContextKey()"></asp:TextBox>
<asp:AutoCompleteExtender ID="AutoCompExt2" BehaviorID="AutoCompBehavior2" runat="server" MinimumPrefixLength="2" CompletionInterval="100" FirstRowSelected="false"
    TargetControlID="TxtSem" EnableCaching="false" CompletionSetCount="10" ServiceMethod="SearchSem" UseContextKey="true"></asp:AutoCompleteExtender>

Also, you probably meant to bind setContextKey to changes to TxtSyllabus, not txtSem.