Button.Command Event
.NET Framework 4.5
Occurs when the Button control is clicked.
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in System.Web.dll)
The Command event is raised when the Button control is clicked. This event is commonly used when a command name, such as Sort, is associated with the Button control. This allows you to create multiple Button controls on a Web page and programmatically determine which Button control is clicked.
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The Command event is raised through the control hierarchy in the form of the BubbleEvent. |
For more information about handling events, see Consuming Events.
The following code example demonstrates how to specify and code an event handler for the Command event to sort a list when the Button control is clicked. This example specifies the event handler declaratively, using the OnClick property of the Button control.
<%@ Page Language="C#" 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"> void CommandBtn_Click(Object sender, CommandEventArgs e) { switch(e.CommandName) { case "Sort": // Call the method to sort the list. Sort_List((String)e.CommandArgument); break; 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((String)e.CommandArgument == "") { // End the message. Message.Text += "."; } else { // Display an error message for the command argument. Message.Text += ", however the command argument is not recogized."; } break; default: // The command name is not recognized. Display an error message. Message.Text = "Command name not recogized."; break; } } void Sort_List(string commandArgument) { switch(commandArgument) { case "Ascending": // Insert code to sort the list in ascending order here. Message.Text = "You clicked the Sort Ascending button."; break; case "Descending": // Insert code to sort the list in descending order here. Message.Text = "You clicked the Sort Descending button."; break; default: // The command argument is not recognized. Display an error message. Message.Text = "Command argument not recogized."; break; } } </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>
The following code example demonstrates how to specify the event handler and programmatically add it to the event in the Page_Load method.
<%@ Page Language="C#" 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"> void CommandBtn_Click(Object sender, CommandEventArgs e) { switch(e.CommandName) { case "Sort": // Call the method to sort the list. Sort_List((String)e.CommandArgument); break; case "Submit": // Display a message for the Submit button being clicked. Message.Text = "You clicked the <b>Submit</b> button"; // Test whether the Command Argument is an empty string (""). if((String)e.CommandArgument == "") { // End the message. Message.Text += "."; } else { // Display an error message for the command argument. Message.Text += ", but the command argument is not recogized."; } break; default: // The command name is not recognized. Display an error message. Message.Text = "Command name not recogized."; break; } } void Sort_List(string commandArgument) { switch(commandArgument) { case "Ascending": // Insert code to sort the list in ascending order here. Message.Text = "You clicked the <b>Sort Ascending</b> button."; break; case "Descending": // Insert code to sort the list in descending order here. Message.Text = "You clicked the <b>Sort Descending</b> button."; break; default: // The command argument is not recognized. Display an error message. Message.Text = "Command argument not recogized."; break; } } void Page_Load(Object sender, EventArgs e) { // Manually register the event-handling method for the Command // event of the Button controls. Button1.Command += new CommandEventHandler(this.CommandBtn_Click); Button2.Command += new CommandEventHandler(this.CommandBtn_Click); Button3.Command += new CommandEventHandler(this.CommandBtn_Click); Button4.Command += new CommandEventHandler(this.CommandBtn_Click); Button5.Command += new CommandEventHandler(this.CommandBtn_Click); } </script> </head> <body> <form id="form1" runat="server"> <h3>Button CommandName Example</h3> Click one of the command buttons. <br /><br /> <asp:Button id="Button1" Text="Sort Ascending" CommandName="Sort" CommandArgument="Ascending" runat="server"/> <asp:Button id="Button2" Text="Sort Descending" CommandName="Sort" CommandArgument="Descending" runat="server"/> <br /><br /> <asp:Button id="Button3" Text="Submit" CommandName="Submit" runat="server"/> <asp:Button id="Button4" Text="Unknown Command Name" CommandName="UnknownName" CommandArgument="UnknownArgument" runat="server"/> <asp:Button id="Button5" Text="Submit Unknown Command Argument" CommandName="Submit" CommandArgument="UnknownArgument" runat="server"/> <br /><br /> <asp:Label id="Message" runat="server"/> </form> </body> </html>
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
