ASP.NET Tutorial/ASP.net Controls/Events

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EventHandler

   <source lang="csharp">

<%@ Page Language="C#" CodeFile="Default.aspx.cs" Inherits="Default_aspx" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>ASP.NET Server Controls</title>

</head> <body>

   <form id="form1" runat="server">

ASP.NET Server Controls

The date and time is <% =DateTime.Now.ToString() %>.

         <asp:TextBox ID="txtBookName" runat="server" Width="250px">Enter a book name.</asp:TextBox>
         <asp:Button ID="btnBookName" runat="server" Text="Book Name" OnClick="btnBookName_Click" />
         <asp:Label ID="lblBookName" runat="server"></asp:Label>
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class Default_aspx : System.Web.UI.Page {

   public Default_aspx()
   {
       Load += new EventHandler(Page_Load);
   }
   protected void btnBookName_Click(object sender, EventArgs e)
   {
      lblBookName.Text = txtBookName.Text;
   }
}</source>
   
  

Get event dispacher from event argument

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="EventTracker" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">

List of events:

   <asp:ListBox id="lstEvents" 
                runat="server" 
                Height="107px" 
                Width="355px">
   </asp:ListBox>


Controls being monitored for change events:

   <asp:TextBox id="txt" 
                runat="server" 
                AutoPostBack="True" 
                OnTextChanged="CtrlChanged"></asp:TextBox>

<asp:CheckBox id="chk" runat="server" AutoPostBack="True" OnCheckedChanged="CtrlChanged"> </asp:CheckBox>

<asp:RadioButton id="opt1" runat="server" GroupName="Sample" AutoPostBack="True" OnCheckedChanged="CtrlChanged"> </asp:RadioButton> <asp:RadioButton id="opt2" runat="server" GroupName="Sample" AutoPostBack="True" OnCheckedChanged="CtrlChanged"> </asp:RadioButton>
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class EventTracker : System.Web.UI.Page {

 protected void CtrlChanged(Object sender, EventArgs e)
 {
   string ctrlName = ((Control)sender).ID;
   lstEvents.Items.Add(ctrlName + " Changed");
   lstEvents.SelectedIndex = lstEvents.Items.Count - 1;
 }

}</source>


The Button_Command event (C#)

   <source lang="csharp">

<%@ 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 void Button_Command(Object sender,
      System.Web.UI.WebControls.rumandEventArgs e)
   {
       switch (e.rumandName)
       {
           case ("DoSomething1"):
               Response.Write("Button 1 was selected");
               break;
           case ("DoSomething2"):
               Response.Write("Button 2 was selected");
               break;
       }
   }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Buttons</title>

</head> <body>

   <form id="form1" runat="server">
       <asp:Button ID="Button1" 
                   Runat="server" Text="Button 1" 
                   OnCommand="Button_Command" 
                   CommandName="DoSomething1" />
       <asp:Button ID="Button2" 
                   Runat="server" 
                   Text="Button 2" 
                   OnCommand="Button_Command" 
                   CommandName="DoSomething2" />    
   </form>

</body> </html></source>


The Button_Command event (VB.net)

   <source lang="csharp">

<%@ 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 Sub Button_Command(ByVal sender As Object, _
     ByVal e As System.Web.UI.WebControls.rumandEventArgs)
       Select Case e.rumandName
           Case "DoSomething1"
               Response.Write("Button 1 was selected")
           Case "DoSomething2"
               Response.Write("Button 2 was selected")
       End Select
   End Sub

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Buttons</title>

</head> <body>

   <form id="form1" runat="server">
       <asp:Button ID="Button1" 
                   Runat="server" 
                   Text="Button 1" 
                   OnCommand="Button_Command" 
                   CommandName="DoSomething1" />
       <asp:Button ID="Button2" 
                   Runat="server" 
                   Text="Button 2" 
                   OnCommand="Button_Command" 
                   CommandName="DoSomething2"/>
   </form>

</body> </html></source>


Two types of events for the button (C#)

   <source lang="csharp">

<%@ Page Language="C#" %> <script runat="server">

   protected void Button1_Click(object sender, EventArgs e)
   {
       Response.Write("Postback!");
   }

</script> <script language="javascript" type="text/javascript">

  function AlertHello()
  { 
     alert("Hello ASP.NET");
  }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Button Server Control</title>

</head> <body>

   <form id="form1" runat="server">
       <asp:Button ID="Button1" 
                   Runat="server" 
                   Text="Button" 
                   OnClientClick="AlertHello()" 
                   OnClick="Button1_Click" />
   </form>

</body> </html></source>


Two types of events for the button (VB)

   <source lang="csharp">

<%@ Page Language="VB" %> <script runat="server">

   Protected Sub Button1_Click(ByVal sender As Object, _
      ByVal e As System.EventArgs)
       Response.Write("Postback!")
   End Sub

</script> <script language="javascript" type="text/javascript">

  function AlertHello()
  { 
     alert("Hello ASP.NET");
  }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Button Server Control</title>

</head> <body>

   <form id="form1" runat="server">
       <asp:Button ID="Button1" 
                   Runat="server" 
                   Text="Button" 
                   OnClientClick="AlertHello()" 
                   OnClick="Button1_Click" />
   </form>

</body> </html></source>