How to stop UpdatePanel from causing whole page postback?

Question

I am using .NET 3.5 and building pages inside of the Community Server 2008 framework.

On one of the pages, I am trying to get an UpdatePanel working.

I took a sample straight from ASP.NET website, update a time in an UpdatePanel to current time by clicking a button, but for some reason when I try and perform the function the whole page refreshes.

Here is what I have:

protected void Button1_Click(object sender, EventArgs e)
{
    Label1.Text = "Panel refreshed at " + DateTime.Now.ToString();
    Label2.Text = "Panel refreshed at " + DateTime.Now.ToString();
}

<asp:ScriptManager ID="ScriptManager1" runat="server"/>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <fieldset>
            <legend>UpdatePanel</legend>
            <asp:Label ID="Label1" runat="server" Text="Panel created."></asp:Label><br />
            <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
        </fieldset>
    </ContentTemplate>
</asp:UpdatePanel>

Whenever I click the button, sure the panel updates - but the whole page posts back! I can see the whole page flashing. What the heck am I doing wrong?

I am inside of a nested Masterpage, but I'm not sure if this is a problem. Could there be something in this Community Server framework that I'm using that causes all events to postback?

Answer 1

Did you try setting Button1 as an AsyncPostBackTrigger in the Triggers section? Set the ChildrenAsTriggers property to true and the UpdateMode property to Conditional.

protected void Button1_Click(object sender, EventArgs e)
{    
    Label1.Text = "Panel refreshed at " + DateTime.Now.ToString();    
    UpdatePanel1.Update();
}    

<asp:ScriptManager ID="ScriptManager1" runat="server"/>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" ChildrenAsTriggers="true" UpdateMode="Conditional">
    <Triggers>        
        <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />    
    </Triggers>    
    <ContentTemplate>        
        <fieldset>            
            <legend>UpdatePanel</legend>            
            <asp:Label ID="Label1" runat="server" Text="Panel created."></asp:Label><br />            
            <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />        
        </fieldset>    
    </ContentTemplate>
</asp:UpdatePanel>