ASP.NET Tutorial/Page Lifecycle/Post Back
Page.IsPostBack (C#)
<source lang="csharp">
<%@ Page Language="C#" %> <script runat="server">
void Page_Load(Object Sender, EventArgs e) { if (!Page.IsPostBack) { lblMessage.Text = "Hello world!!!!"; } } void Submit(Object Sender, EventArgs e) { lblMessage2.Text = "Form posted"; }
</script> <html><body>
<form runat="server"> <asp:Button id="btSubmit" runat="server" Text="Submit" onClick="Submit" /> <asp:Label id="lblMessage" runat=server /> <asp:Label id="lblMessage2" runat=server /> </form>
</body></html></source>
Save value to view state (VB.net)
<source lang="csharp">
<%@ Page Language="VB" %> <script runat="server">
Sub Page_Load(Sender as Object, e as EventArgs) if not Page.IsPostBack then ViewState("StartTime") = DateTime.Now lblMessage.Text = "The time is now: " & _ ViewState("StartTime") end if end sub Sub Submit(obj as object, e as EventArgs) lblMessage.Text = "The time is now: " & DateTime.Now & _ "
started at: " & ViewState("StartTime") end Sub
</script> <html><body>
<form runat="server"> <asp:Button id="btSubmit" runat="server" Text="Submit" onClick="Submit" /> <asp:Label id="lblMessage" runat=server /> </form>
</body></html></source>