Unable to download file using AsyncPostBackTrigger in RadGrid - telerik

Question

Hi all I am using RadGrid in my application, as I want my RadGrid not to refresh I had my RadGrid in an Update Panel as follows
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="RadGrid1" EventName="ItemCommand" />
<%--<asp:PostBackTrigger ControlID="RadGrid1" />--%>
</Triggers>
<ContentTemplate>
<telerik:RadGrid ID="RadGrid1" runat="server" AutoGenerateColumns="false" OnItemCommand="RadGrid1_ItemCommand"
OnNeedDataSource="RadGrid1_NeedDataSource">
<MasterTableView Width="950" AutoGenerateColumns="false" DataKeyNames="EmpID" GridLines="None"
TableLayout="Auto">
<Columns>
<telerik:GridBoundColumn DataField="EmpID" HeaderText="Emp ID" ReadOnly="true" HeaderStyle-HorizontalAlign="Left"
ItemStyle-HorizontalAlign="Left" UniqueName="EmpID" FilterControlWidth="30px"
AutoPostBackOnFilter="true" CurrentFilterFunction="Contains" />
<telerik:GridButtonColumn DataTextField="ButtonName" ItemStyle-ForeColor="Blue" CommandName="Generate"
ConfirmTextFields="ButtonName" ConfirmTextFormatString="Would you like to {0} ACH file ?"
ConfirmDialogType="RadWindow" Reorderable="false" UniqueName="ButtonName" ConfirmTitle="ACH File">
</telerik:GridButtonColumn>
<telerik:GridBoundColumn DataField="EmployeeName" HeaderText="Employee Name" ReadOnly="true"
HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left" UniqueName="EmployeeName"
FilterControlWidth="60px" AutoPostBackOnFilter="true" CurrentFilterFunction="Contains" />
</Columns>
</MasterTableView>
</telerik:RadGrid>
</ContentTemplate>
</asp:UpdatePanel>
When I click on download button I am unable to download the file this is my code in Itemcommand
protected void RadGrid1_ItemCommand(object sender, Telerik.Web.UI.GridCommandEventArgs e)
{
if (e.CommandName == "Generate")
{
Response.ContentType = "text/plain";
Response.AppendHeader("Content-Disposition", "attachment;filename= errorLog.txt");
Response.AddHeader("content-length", "0");
Response.Flush();
Response.End();
}
}
Can some one help me how can I work out this using AsyncPostBackTrigger

Answer 1

You cannot call Response with AsyncPostBack. It is Ajax Framework limitation.
Updated 1/28/2013
Since you are using telerik, I prefer using RadAjaxManager. Basically, when Generate button is clicked, it uses regular post back instead of ajax. In my example, sorting still uses ajax.
<telerik:RadGrid ID="RadGrid1" AutoGenerateColumns="false" AllowSorting="True" runat="server"
OnNeedDataSource="RadGrid1_NeedDataSource" OnItemCommand="RadGrid1_ItemCommand">
<MasterTableView DataKeyNames="EmpID">
<Columns>
<telerik:GridTemplateColumn>
<ItemTemplate>
<asp:Button runat="server" CommandName="Generate" ID="GenerateButton"
Text="Generate" OnClientClick="Generate(this, event); return false;" />
</ItemTemplate>
</telerik:GridTemplateColumn>
<telerik:GridBoundColumn DataField="EmpID" HeaderText="Emp ID" UniqueName="EmpID" SortExpression="EmpID" />
<telerik:GridBoundColumn DataField="EmployeeName" HeaderText="Employee Name" UniqueName="EmployeeName" />
</Columns>
</MasterTableView>
</telerik:RadGrid>
<%-- RadAjaxManager --%>
<telerik:RadAjaxManager ID="RadAjaxManager1" runat="server">
<AjaxSettings>
<telerik:AjaxSetting AjaxControlID="RadGrid1">
<UpdatedControls>
<telerik:AjaxUpdatedControl ControlID="RadGrid1" LoadingPanelID="RadAjaxLoadingPanel1" />
</UpdatedControls>
</telerik:AjaxSetting>
</AjaxSettings>
</telerik:RadAjaxManager>
<%-- RadAjaxLoadingPanel --%>
<telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" Skin="Default">
</telerik:RadAjaxLoadingPanel>
<telerik:RadCodeBlock ID="RadCodeBlock1" runat="server">
<script type="text/javascript">
function Generate(sender, e) {
$find("<%= RadAjaxManager1.ClientID %>").__doPostBack(sender.name, "");
}
</script>
</telerik:RadCodeBlock>
public class Employee
{
public int EmpID { get; set; }
public string EmployeeName { get; set; }
}
protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
RadGrid1.DataSource = new List<Employee>
{
new Employee {EmpID = 1, EmployeeName = "John"},
new Employee {EmpID = 2, EmployeeName = "Marry"},
new Employee {EmpID = 3, EmployeeName = "Eric"}
};
}
protected void RadGrid1_ItemCommand(object sender, GridCommandEventArgs e)
{
if (e.CommandName == "Generate")
{
Response.ContentType = "text/plain";
Response.AppendHeader("Content-Disposition", "attachment;filename= errorLog.txt");
Response.AddHeader("content-length", "0");
Response.Flush();
Response.End();
}
}