Refresh ASP.NET page using custom event

Question

I have created a List which generates a custom event based on Example 1 from this page, and I need to update an aspx page whenever there are any new elements in the List.

When I debug the application I can see that the value was updated, but nothing appears on the page.

ASPX

        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="false">
            <ContentTemplate>
                <fieldset>
                <legend>UpdatePanel</legend>
                <asp:Label ID="xpto" runat="server" Text="zzzzzzzzzzzz"></asp:Label>
                </fieldset>
            </ContentTemplate>
        </asp:UpdatePanel>

Code Behind

MessageHandling.DashboardRequests.Changed += new EventHandler(ListChanged);
...
...
...
private void ListChanged(object sender, EventArgs e)
{
    DateTime dt = DateTime.Now;
    xpto.Text = dt.ToString();
}

EDIT:

If I change the UpdateMode to Always and ListChanged method to:

private void ListChanged(object sender, EventArgs e)
{
  DateTime dt = DateTime.Now;
  xpto.Text = dt.ToString();
  UpdatePanel1.Update();
}

I get the following error:

The Update method can only be called on UpdatePanel with ID 'UpdatePanel1' when UpdateMode is set to Conditional.

And if I set the UpdateMode to Conditional nothing happens again.

If I create a timer and add this method:

protected void Timer1_Tick(object sender, EventArgs e)
{
  DateTime dt = DateTime.Now;
  xpto.Text = dt.ToString();
}

the xpto is updated in the timer method correctly

Why are you using UpdateMode="Conditional"? and when are you updating the UpdatePanel? Check UpdatePanel UpdateMode Property — Bastardo
– Bastardo, Commented Nov 25, 2011 at 16:17
@AteşGÜRAL - Your link is wrong I think you meant this msdn.microsoft.com/en-us/library/… — Hogan
– Hogan, Commented Nov 25, 2011 at 16:23
balizeiro I think there is a misunderstanding here, if you set Update mode to Always you don't need to do UpdatePanel1.Update() I mean at least that is how I use it.So set it conditional and do UpdatePanel1.Update() when needed, or set it to always and do not use UpdatePanel1.Update(). — Bastardo
– Bastardo, Commented Nov 25, 2011 at 21:37
I tried both of those manners but nothing happens. The weird thing is if I try the update from a Timer event, everything works OK. — Gonçalo Cardoso
– Gonçalo Cardoso, Commented Nov 26, 2011 at 18:44

Hogan · Accepted Answer · 2011-11-25 16:24:24Z

1

Change UpdateMode to Always as suggested by Ates.

(old)

The code looks ok, so I will make a WAG -- are you updating xpto.Text ANYWHERE else in the page lifecycle?

edited Nov 25, 2011 at 16:24

answered Nov 25, 2011 at 16:00

Hogan

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2 Comments

Gonçalo Cardoso Over a year ago

No, the only place where xpto is referenced is in ListChanged(...)

Hogan Over a year ago

I'd have to see the rest of your code, I will note the example you were looking at is not an ASP.NET example but a windows forms example

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