G
Guest
Hi,
Is there a way to update the text of an asp:label on a webform without
refreshing the entire page? What is called by button clicks and other
events that refresh a webform control?
See the example WebForm1.aspx and WebForm1.aspx.cs code below:
WebForm1.aspx
=======================================================
<%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="updateLabelTest.WebForm1" %>
<HTML>
<HEAD>
<title>WebForm1</title>
</HEAD>
<body >
<form id="Form1" method="post" runat="server">
<asp:Button id=Button1 runat="server" Text="Button"></asp:Button>
<asp:Label id=Label1 runat="server">Label</asp:Label>
<br>
<asp:Button id=Button2 runat="server" Text="Button"></asp:Button>
<asp:Label id=Label2 runat="server">Label</asp:Label>
</form>
</body>
</HTML>
WebForm1.aspx.cs
=======================================================
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace updateLabelTest
{
/// <summary>
/// Summary description for WebForm1.
/// </summary>
public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Label Label1;
protected System.Web.UI.WebControls.Button Button1;
protected System.Web.UI.WebControls.Label Label2;
protected System.Web.UI.WebControls.Button Button2;
int nTotalSeconds = 0;
int nIntervalInSeconds = 5;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
}
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.Button1.Click += new System.EventHandler(this.Button1_Click);
this.Button2.Click += new System.EventHandler(this.Button2_Click);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
// Option 1: Simply update the label Text within a loop
private void Button1_Click(object sender, System.EventArgs e)
{
// Trying to update the text of the asp:label every second.
// Label1.Text does not get updated until
// after Button1_Click returns.
// Thus, i = 4 shows up, but we never see i = 1, 2, or 3.
//
// I realize this could be done via javascript using:
// <meta http-equiv="refresh" content="5">
// However, I have a more complex C# website application that
// requires updating from within the asp.net CodeBehind.
for( int i=1; i < 5; i++ )
{
Label1.Text = i.ToString();
System.Threading.Thread.Sleep( 1000 );
}
}
// Option 2: Update using a System Timer
private void Button2_Click(object sender, System.EventArgs e)
{
// I'd prefer to use a Timer and update based on the Timer Interval.
// I don't understand why Label2.Text never gets updated despite
// MyTimerEventHandler firing even 5 seconds.
System.Timers.Timer myTimer = new System.Timers.Timer();
myTimer.Elapsed += new System.Timers.ElapsedEventHandler(
MyTimerEventHandler );
myTimer.Interval = nIntervalInSeconds*1000;
myTimer.Start();
}
private void MyTimerEventHandler( object source,
System.Timers.ElapsedEventArgs e )
{
nTotalSeconds += nIntervalInSeconds;
Label2.Text = "timer " + nTotalSeconds.ToString();
}
}
}
Is there a way to update the text of an asp:label on a webform without
refreshing the entire page? What is called by button clicks and other
events that refresh a webform control?
See the example WebForm1.aspx and WebForm1.aspx.cs code below:
WebForm1.aspx
=======================================================
<%@ Page language="c#" Codebehind="WebForm1.aspx.cs"
AutoEventWireup="false" Inherits="updateLabelTest.WebForm1" %>
<HTML>
<HEAD>
<title>WebForm1</title>
</HEAD>
<body >
<form id="Form1" method="post" runat="server">
<asp:Button id=Button1 runat="server" Text="Button"></asp:Button>
<asp:Label id=Label1 runat="server">Label</asp:Label>
<br>
<asp:Button id=Button2 runat="server" Text="Button"></asp:Button>
<asp:Label id=Label2 runat="server">Label</asp:Label>
</form>
</body>
</HTML>
WebForm1.aspx.cs
=======================================================
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace updateLabelTest
{
/// <summary>
/// Summary description for WebForm1.
/// </summary>
public class WebForm1 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.Label Label1;
protected System.Web.UI.WebControls.Button Button1;
protected System.Web.UI.WebControls.Label Label2;
protected System.Web.UI.WebControls.Button Button2;
int nTotalSeconds = 0;
int nIntervalInSeconds = 5;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
}
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.Button1.Click += new System.EventHandler(this.Button1_Click);
this.Button2.Click += new System.EventHandler(this.Button2_Click);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
// Option 1: Simply update the label Text within a loop
private void Button1_Click(object sender, System.EventArgs e)
{
// Trying to update the text of the asp:label every second.
// Label1.Text does not get updated until
// after Button1_Click returns.
// Thus, i = 4 shows up, but we never see i = 1, 2, or 3.
//
// I realize this could be done via javascript using:
// <meta http-equiv="refresh" content="5">
// However, I have a more complex C# website application that
// requires updating from within the asp.net CodeBehind.
for( int i=1; i < 5; i++ )
{
Label1.Text = i.ToString();
System.Threading.Thread.Sleep( 1000 );
}
}
// Option 2: Update using a System Timer
private void Button2_Click(object sender, System.EventArgs e)
{
// I'd prefer to use a Timer and update based on the Timer Interval.
// I don't understand why Label2.Text never gets updated despite
// MyTimerEventHandler firing even 5 seconds.
System.Timers.Timer myTimer = new System.Timers.Timer();
myTimer.Elapsed += new System.Timers.ElapsedEventHandler(
MyTimerEventHandler );
myTimer.Interval = nIntervalInSeconds*1000;
myTimer.Start();
}
private void MyTimerEventHandler( object source,
System.Timers.ElapsedEventArgs e )
{
nTotalSeconds += nIntervalInSeconds;
Label2.Text = "timer " + nTotalSeconds.ToString();
}
}
}