<script type="text/javascript">
    var renderFileLink = function (value, meta, record) {
        var a = Ext.net.DirectMethods.<%=ClientID%>.GetFilePath(record.data.Source, record.data.FileName, record.data.TypeId);
        alert(a);
        return a;
    }
    
</script>

<!--some code  ------>
<ColumnModel runat="server">
        <Columns>
            <ext:Column Header="Описание файла" DataIndex="Description" Width="250">
                <Renderer Fn="renderFileLink" />
            </ext:Column>
        </Columns>
    </ColumnModel>

[DirectMethod]
public string GetFilePath(Guid sourceId, string fileName, int fileType) {
       var a = sourceId.ToString() + fileName + fileType.ToString();
       return a;
}
The function renderFileLink always returns "undefined", but the method "GetFilePath" returns the other (properly) data. But I want to display the data which has been received from the method "GetFilePath". How can I do it?