Button Class
Assembly: System.Web (in system.web.dll)
'Declaration Public Class Button Inherits WebControl Implements IButtonControl, IPostBackEventHandler 'Usage Dim instance As Button
public class Button extends WebControl implements IButtonControl, IPostBackEventHandler
public class Button extends WebControl implements IButtonControl, IPostBackEventHandler
Not applicable.
Use the Button control to create a push button on the Web page. You can create either a Submit button or a Command button.
By default, a Button control is a Submit button. A Submit button does not have a command name (specified by the CommandName property) associated with the button and simply posts the Web page back to the server. You can provide an event handler for the Click event to programmatically control the actions performed when the Submit button is clicked.
A Command button has a command name associated with the button, such as Sort, by setting the CommandName property. This allows you to create multiple Button controls on a Web page and programmatically determine which Button control is clicked. You can also use the CommandArgument property with a command button to provide additional information about the command to perform, such as Ascending. You can provide an event handler for the Command event to programmatically control the actions performed when the Command button is clicked.
By default, page validation is performed when a Button control is clicked. Page validation determines whether the input controls associated with a validation control on the page all pass the validation rules specified by the validation control. To prevent page validation from occurring, set the CausesValidation property to false.
Accessibility
The markup rendered by default for this control might not conform to accessibility standards such as the Web Content Accessibility Guidelines 1.0 (WCAG) priority 1 guidelines. For details about accessibility support for this control, see ASP.NET Controls and Accessibility.
The following code example demonstrates how to create a Submit Button control that posts the Web page content back to the server.
<%@ Page Language="VB" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Button Example</title> <script language="VB" runat="server"> Sub SubmitBtn_Click(sender As Object, e As EventArgs) Message.Text = "Hello World!!" End Sub 'SubmitBtn_Click </script> </head> <body> <form id="form1" runat="server"> <h3>Button Example</h3> Click on the submit button.<br /><br /> <asp:Button id="Button1" Text="Submit" OnClick="SubmitBtn_Click" runat="server"/> <br /> <asp:label id="Message" runat="server"/> </form> </body> </html>
The following code example demonstrates how to create a Command Button control that sorts a list.
<%@ Page Language="VB" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Button CommandName Example</title> <script runat="server"> Sub CommandBtn_Click(sender As Object, e As CommandEventArgs) Select e.CommandName Case "Sort" ' Call the method to sort the list. Sort_List(CType(e.CommandArgument, String)) Case "Submit" ' Display a message for the Submit button being clicked. Message.Text = "You clicked the Submit button" ' Test whether the command argument is an empty string (""). If CType(e.CommandArgument , String) = "" Then ' End the message. Message.Text &= "." Else ' Display an error message for the command argument. Message.Text &= ", however the command argument is not recogized." End If Case Else ' The command name is not recognized. Display an error message. Message.Text = "Command name not recogized." End Select End Sub Sub Sort_List(commandArgument As String) Select commandArgument Case "Ascending" ' Insert code to sort the list in ascending order here. Message.Text = "You clicked the Sort Ascending button." Case "Descending" ' Insert code to sort the list in descending order here. Message.Text = "You clicked the Sort Descending button." Case Else ' The command argument is not recognized. Display an error message. Message.Text = "Command argument not recogized." End Select End Sub </script> </head> <body> <form id="form1" runat="server"> <h3>Button CommandName Example</h3> Click on one of the command buttons. <br /><br /> <asp:Button id="Button1" Text="Sort Ascending" CommandName="Sort" CommandArgument="Ascending" OnCommand="CommandBtn_Click" runat="server"/> <asp:Button id="Button2" Text="Sort Descending" CommandName="Sort" CommandArgument="Descending" OnCommand="CommandBtn_Click" runat="server"/> <br /><br /> <asp:Button id="Button3" Text="Submit" CommandName="Submit" OnCommand="CommandBtn_Click" runat="server"/> <asp:Button id="Button4" Text="Unknown Command Name" CommandName="UnknownName" CommandArgument="UnknownArgument" OnCommand="CommandBtn_Click" runat="server"/> <asp:Button id="Button5" Text="Submit Unknown Command Argument" CommandName="Submit" CommandArgument="UnknownArgument" OnCommand="CommandBtn_Click" runat="server"/> <br /><br /> <asp:Label id="Message" runat="server"/> </form> </body> </html>
- AspNetHostingPermission for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.
- AspNetHostingPermission for operating in a hosted environment. Demand value: InheritanceDemand; Permission value: Minimal.
System.Web.UI.Control
System.Web.UI.WebControls.WebControl
System.Web.UI.WebControls.Button