CommandEventArgs Class

 

Provides data for the Command event.

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)


Public Class CommandEventArgs
	Inherits EventArgs

NameDescription
System_CAPS_pubmethodCommandEventArgs(CommandEventArgs)

Initializes a new instance of the CommandEventArgs class with another CommandEventArgs object.

System_CAPS_pubmethodCommandEventArgs(String, Object)

Initializes a new instance of the CommandEventArgs class with the specified command name and argument.

NameDescription
System_CAPS_pubpropertyCommandArgument

Gets the argument for the command.

System_CAPS_pubpropertyCommandName

Gets the name of the command.

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

The Command event is raised when a Button or ImageButton control is clicked.

The CommandEventArgs object contains data about the Command event that can be accessed in the event handler. Using the properties available in the CommandEventArgs class, you can determine the name of the command to perform, such as Sort, in addition to an optional argument that supplements the command, such as Ascending.

For a list of initial property values for an instance of CommandEventArgs, see the CommandEventArgs constructor.

For more information about handling events, see NIB: Consuming Events.

The following example demonstrates how to access the properties in CommandEventArgs to determine the command to perform. This example specifies the event handler declaratively, using the OnClick property of the Button control.

<%@ 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"/>

      &nbsp;

      <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"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           OnCommand="CommandBtn_Click" 
           runat="server"/>

      &nbsp;

      <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="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 <b>Submit</b> 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 &= ", but 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 <b>Sort Ascending</b> button."

            Case "Descending"

               ' Insert code to sort the list in descending order here.
               Message.Text = "You clicked the <b>Sort Descending</b> button."

            Case Else

               ' The command argument is not recognized. Display an error message.
               Message.Text = "Command argument not recogized."

         End Select

      End Sub

      Sub Page_Load(sender As Object, e As EventArgs)

         ' Manually register the event-handling method for the Command  
         ' event of the Button controls.
         AddHandler Button1.Command, AddressOf CommandBtn_Click
         AddHandler Button2.Command, AddressOf CommandBtn_Click
         AddHandler Button3.Command, AddressOf CommandBtn_Click
         AddHandler Button4.Command, AddressOf CommandBtn_Click
         AddHandler Button5.Command, AddressOf CommandBtn_Click

      End Sub

   </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"/>

      &nbsp;

      <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"/>

      &nbsp;

      <asp:Button id="Button4"
           Text="Unknown Command Name"
           CommandName="UnknownName"
           CommandArgument="UnknownArgument"
           runat="server"/>

      &nbsp;

      <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>

.NET Framework
Available since 1.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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