UpdatePanelUpdateMode Enum
Definition
Important
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Represents the possible update modes for the content in an UpdatePanel control.
public enum class UpdatePanelUpdateModepublic enum UpdatePanelUpdateModetype UpdatePanelUpdateMode = Public Enum UpdatePanelUpdateMode- Inheritance
Fields
| Name | Value | Description |
|---|---|---|
| Always | 0 | The content of the UpdatePanel control is updated for all postbacks that originate from the page. This includes asynchronous postbacks. |
| Conditional | 1 | Specifies a number of conditions under which the content of the UpdatePanel control is updated; see the Remarks section for more information. |
Examples
The following example declares two UpdatePanel controls. The first panel sets the UpdatePanel.UpdateMode property to Conditional. The second panel has UpdatePanel.UpdateMode set to Always by default. A button outside both panels is registered as an asynchronous postback control by using the ScriptManager.RegisterAsyncPostBackControl method. In the button's click event handler, the UpdatePanel.Update method of the first panel is called if more than five seconds have elapsed since its last update. In this scenario, the panel's content is updated only if the last panel update was more than five seconds ago. The second panel's content is always updated.
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
protected DateTime LastUpdate
{
get
{
return (DateTime)(ViewState["LastUpdate"] ?? DateTime.Now);
}
set
{
ViewState["LastUpdate"] = value;
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (LastUpdate.AddSeconds(5.0) < DateTime.Now)
{
UpdatePanel1.Update();
LastUpdate = DateTime.Now;
}
}
protected void Page_Load(object sender, EventArgs e)
{
ScriptManager1.RegisterAsyncPostBackControl(Button1);
if (!IsPostBack)
{
LastUpdate = DateTime.Now;
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>UpdatePanelUpdateMode Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1"
runat="server" />
<asp:Panel ID="Panel1"
GroupingText="UpdatePanel1"
runat="server">
<asp:UpdatePanel ID="UpdatePanel1"
UpdateMode="Conditional"
runat="server">
<ContentTemplate>
<p>
The content in this UpdatePanel only refreshes if five or more
seconds have passed since the last refresh and the button in
UpdatePanel2 was clicked. The time is checked
server-side and the UpdatePanel.Update() method is called. Last
updated: <strong>
<%= LastUpdate.ToString() %>
</strong>
</p>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
<asp:Panel ID="Panel2"
GroupingText="UpdatePanel2"
runat="server">
<asp:UpdatePanel ID="UpdatePanel2"
runat="server">
<ContentTemplate>
<p>
This UpdatePanel always refreshes if the button is clicked.
Last updated: <strong>
<%= DateTime.Now.ToString() %>
</strong>
</p>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
<asp:Button ID="Button1" Text="Button1" runat="server" OnClick="Button1_Click" />
</div>
</form>
</body>
</html>
<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Protected Property LastUpdate() As DateTime
Get
If ViewState("LastUpdate") IsNot Nothing Then
Return ViewState("LastUpdate")
Else : Return DateTime.Now()
End If
End Get
Set(ByVal Value As DateTime)
ViewState("LastUpdate") = Value
End Set
End Property
Protected Sub Button1_Click(ByVal Sender As Object, ByVal E As EventArgs)
If (LastUpdate.AddSeconds(5.0) < DateTime.Now) Then
UpdatePanel1.Update()
LastUpdate = DateTime.Now
End If
End Sub
Protected Sub Page_Load(ByVal Sender As Object, ByVal E As EventArgs)
ScriptManager1.RegisterAsyncPostBackControl(Button1)
If Not IsPostBack Then
LastUpdate = DateTime.Now
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>UpdatePanelUpdateMode Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1"
runat="server" />
<asp:Panel ID="Panel1"
GroupingText="UpdatePanel1"
runat="server">
<asp:UpdatePanel ID="UpdatePanel1"
runat="server"
UpdateMode="Conditional">
<ContentTemplate>
<p>
The content in this UpdatePanel only refreshes if five or more
seconds have passed since the last refresh and the button in
UpdatePanel2 was clicked. The time is checked
server-side and the UpdatePanel.Update() method is called. Last
updated: <strong>
<%= LastUpdate.ToString() %>
</strong>
</p>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
<asp:Panel ID="Panel2"
GroupingText="UpdatePanel2"
runat="server">
<asp:UpdatePanel ID="UpdatePanel2"
runat="server">
<ContentTemplate>
<p>
This UpdatePanel always refreshes if the button is clicked.
Last updated: <strong>
<%= DateTime.Now.ToString() %>
</strong>
</p>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
<asp:Button ID="Button1" Text="Button1" runat="server" OnClick="Button1_Click" />
</div>
</form>
</body>
</html>
Remarks
The UpdatePanelUpdateMode enumeration is used by the UpdatePanel.UpdateMode property and defines the possible update modes for the content of an UpdatePanel control. The UpdatePanel control requires that the ScriptManager.EnablePartialRendering property be true for partial-page rendering to occur.
The default value of the UpdatePanel.UpdateMode property is Always.
If the UpdatePanel control is inside another UpdatePanel control and the parent panel is updated, the nested panel will also be updated regardless of the UpdateMode property value.
The Conditional value updates the content of the UpdatePanel control under the following conditions:
The UpdatePanel.Update method is called explicitly.
A control is defined as a trigger by using the UpdatePanel.Triggers property and causes a postback. In this scenario, the control is an explicit trigger for updating the panel content. The trigger control can be either inside or outside the UpdatePanel control that defines the trigger.
The UpdatePanel.ChildrenAsTriggers property is set to
trueand a child control of the UpdatePanel control causes a postback. In this scenario, child controls of the UpdatePanel control are implicit triggers for updating the panel. Child controls of nested UpdatePanel controls do not cause the outer UpdatePanel control to be updated unless they are explicitly defined as triggers.
