ItemCommand Event (ObjectList)

Article
09/14/2006

Occurs when the user selects a command that is associated with an ObjectList item.

public event ObjectListCommandEventHandler ItemCommand

Remarks

When an ItemCommand event handler is defined, the ObjectList control notifies the handler when an item event is generated through user interaction.

When you render an object list by using templates, the ItemCommand event handler is called through the event-bubbling mechanism of ASP.NET. The event handler is passed an argument of typeObjectListCommandEventArgs, which contains information about the source item and the CommandName property of the control that generated the event. This allows you to render a single item with multiple associated interactions.

On default rendering, the control renders each of the commands defined for the object list as a link. When the user clicks a link, the ItemCommand event handler is called with an argument of type ObjectListCommandEventArgs, which contains information about the source item. The value in the CommandName property is the name of the command that the user invoked.

Example

The following example demonstrates how to trap the ItemCommand event. The CommandName property specifies what action to perform.

<Script language="vb" runat="server">

Dim Command1 As System.Web.UI.MobileControls.ObjectListCommand
Dim Command2 As System.Web.UI.MobileControls.ObjectListCommand

Class Book
   Private _BookName, _Author, _InStock As String
   
   
   Public Sub New(BookName As String, Author As String, InStock As String)
      _BookName = BookName
      _Author = Author
      _InStock = InStock
   End Sub 'New
   
   
   Public ReadOnly Property BookName() As String
      Get
         Return _BookName
      End Get
   End Property
   
   Public ReadOnly Property Author() As String
      Get
         Return _Author
      End Get
   End Property
   
   Public ReadOnly Property InStock() As String
      Get
         Return _InStock
      End Get
   End Property
End Class


Sub SelectCommand(sender As Object, e As ObjectListShowCommandsEventArgs)
   If CType(e.ListItem.DataItem, Book).InStock = "Yes" Then
      ObjectList1.Commands.Add(Command1)
   Else
      ObjectList1.Commands.Add(Command2)
   End If
End Sub


Sub AskForBook(sender As Object, e As ObjectListCommandEventArgs)
      
   ' Selected ObjectListCommand from ObjectListCommandCollection. 
   ' You can reference it and perform an action on it depending
   ' on the value of the CommandName property.
   If e.CommandName = "CheckOut" Then
      ActiveForm = Form2
   Else 
      If e.CommandName = "Reserve" Then
         ActiveForm = Form3
      End If
   End If

End Sub

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
   ' Create and fill an array.
   Dim arr As New ArrayList()
   arr.Add(New Book("Sushi, Anyone?", "O'Leary", "Yes"))
   arr.Add(New Book("Secrets of Silicon Valley", "Dull", "No"))
   arr.Add(New Book("Net Etiquette", "Locksley", "Yes"))
   arr.Add(New Book("The Gourmet Microwave", "Ringer", "No"))

   ' Associate and bind array to the ObjectList object.
   ObjectList1.DataSource = arr
   ObjectList1.DataBind()

   ' Override autogeneration.
   ObjectList1.LabelField = "BookName"

   Command1 = New System.Web.UI.MobileControls.ObjectListCommand("CheckOut", "CheckOut")
   Command2 = New System.Web.UI.MobileControls.ObjectListCommand("Reserve", "Reserve")
End Sub
    
    
</Script>

<mobile:Form runat="server" id="Form1" >
<mobile:ObjectList id="ObjectList1" runat="server" OnItemCommand="AskForBook" OnShowItemCommands="SelectCommand">
</mobile:ObjectList>
<mobile:Label id="Label1" runat="server"></mobile:Label>
</mobile:Form>
<mobile:Form id="Form3" runat="server">
<mobile:Label id="Label2" runat="server">Placed On Reserve!</mobile:Label>
</mobile:Form>
<mobile:Form id="Form2" runat="server">
<mobile:Label id="Label3" runat="server">Successfully Checked Out!</mobile:Label>
</mobile:Form>


[C#]

<script Language="c#" runat="server">

System.Web.UI.MobileControls.ObjectListCommand Command1;
System.Web.UI.MobileControls.ObjectListCommand Command2;

class Book
{
   private String _BookName, _Author, _InStock;
   
   public Book(String BookName, String Author, String InStock) 
   { 
      _BookName = BookName; 
      _Author = Author;
      _InStock = InStock;
   }

   public String BookName { get { return _BookName; } }
   public String Author { get { return _Author; } }
   public String InStock { get { return _InStock; } }
}

public void Page_Load(Object sender, EventArgs e)
{
   // Create and fill an array.
   ArrayList arr = new ArrayList();
   arr.Add (new Book ("Sushi, Anyone?", "O'Leary", "Yes"));
   arr.Add (new Book ("Secrets of Silicon Valley", "Dull", "No"));
   arr.Add (new Book ("Net Etiquette", "Locksley", "Yes"));
   arr.Add (new Book ("The Gourmet Microwave", "Ringer", "No"));

   // Associate and bind array to the ObjectList object.
   ObjectList1.DataSource = arr;
   ObjectList1.DataBind ();

   // Override autogeneration.
   ObjectList1.LabelField = "BookName";

   Command1 = new System.Web.UI.MobileControls.ObjectListCommand
      ("CheckOut", "CheckOut");
   Command2 = new System.Web.UI.MobileControls.ObjectListCommand
      ("Reserve", "Reserve");
}

void SelectCommand(Object sender, 
   ObjectListShowCommandsEventArgs e)
{
   if ( ((Book)e.ListItem.DataItem).InStock == "Yes" )
   {
      ObjectList1.Commands.Add(Command1);
   }
   else
   {
      ObjectList1.Commands.Add(Command2);
   }  
}

void AskForBook(Object sender, ObjectListCommandEventArgs e)
{
   // Selected ObjectListCommand from ObjectListCommandCollection. 
   // You can reference it and perform an action on it depending
   // on the value of the CommandName property.

   if (e.CommandName == "CheckOut")
   {
      ActiveForm = Form2;
   }
   else if (e.CommandName == "Reserve")
   {
      ActiveForm = Form3;
   }
}
</script>

<mobile:Form runat="server" id="Form1" >
<mobile:ObjectList id="ObjectList1" runat="server" OnItemCommand="AskForBook" OnShowItemCommands="SelectCommand">
</mobile:ObjectList>
<mobile:Label id="Label1" runat="server"></mobile:Label>
</mobile:Form>
<mobile:Form id="Form3" runat="server">
<mobile:Label id="Label2" runat="server">Placed On Reserve!</mobile:Label>
</mobile:Form>
<mobile:Form id="Form2" runat="server">
<mobile:Label id="Label3" runat="server">Successfully Checked Out!</mobile:Label>
</mobile:Form>

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ItemCommand Event (ObjectList)

Remarks

Example

See Also

Additional resources