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DataList.OnItemCommand Method

Raises the ItemCommand event. This allows you to provide a custom handler for the event.

[Visual Basic]
Protected Overridable Sub OnItemCommand( _
   ByVal e As DataListCommandEventArgs _
)
[C#]
protected virtual void OnItemCommand(
 DataListCommandEventArgs e
);
[C++]
protected: virtual void OnItemCommand(
 DataListCommandEventArgs* e
);
[JScript]
protected function OnItemCommand(
   e : DataListCommandEventArgs
);

Parameters

e
A DataListCommandEventArgs that contains event data.

Remarks

Use the OnItemCommand method to provide a custom handler for the ItemCommand event.

The ItemCommand event is raised when any button is clicked in the DataList control and is commonly used when you have a button control with a custom CommandName value, such as Add, in the DataList control.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The OnItemCommand method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors:  When overriding OnItemCommand in a derived class, be sure to call the base class's OnItemCommand method so that registered delegates receive the event.

Example

[Visual Basic, C#] The following example demonstrates how to specify and code a handler for the ItemCommand event to select an item from the DataList control.

[Visual Basic, C#] Note   The following code sample uses the single-file code model and may not work correctly if copied directly into a code-behind file. This code sample must be copied into an empty text file that has an .aspx extension. For more information on the Web Forms code model, see Web Forms Code Model.
[Visual Basic] 

<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<html>
<head>

   <script runat="server">

      Function CreateDataSource() As ICollection 
      
         ' Create sample data for the DataList control.
         Dim dt As DataTable = New DataTable()
         Dim dr As DataRow
 
         ' Define the columns of the table.
         dt.Columns.Add(New DataColumn("Item", GetType(Int32)))
         dt.Columns.Add(New DataColumn("Qty", GetType(Int32)))
         dt.Columns.Add(New DataColumn("Price", GetType(Double)))
 
         ' Populate the table with sample values.
         Dim i As Integer

         For i = 0 To 8 

            dr = dt.NewRow()
 
            dr(0) = i
            dr(1) = i * 2
            dr(2) = 1.23 * (i + 1)
 
            dt.Rows.Add(dr)
         
         Next i
 
         Dim dv As DataView = New DataView(dt)
         Return dv
      
      End Function
 
      Sub Page_Load(sender As Object, e As EventArgs) 

         ' Load sample data only once, when the page is first loaded.
         If Not IsPostBack Then 
         
            ItemsList.DataSource = CreateDataSource()
            ItemsList.DataBind()
         
         End If

      End Sub

      Sub Item_Command(sender As Object, e As DataListCommandEventArgs) 
        
         ' Set the SelectedIndex property to select an item in the DataList.
         ItemsList.SelectedIndex = e.Item.ItemIndex

         ' Rebind the data source to the DataList to refresh the control.
         ItemsList.DataSource = CreateDataSource()
         ItemsList.DataBind()

      End Sub

   </script>

</head>
<body>

   <form runat="server">

      <h3>DataList Select Example</h3>

      Click <b>Select</b> to select an item.

      <br><br>
       
      <asp:DataList id="ItemsList"
           GridLines="Both"
           CellPadding="3"
           CellSpacing="0"           
           OnItemCommand="Item_Command"
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <AlternatingItemStyle BackColor="Gainsboro">
         </AlternatingItemStyle>

         <SelectedItemStyle BackColor="Yellow">
         </SelectedItemStyle>

         <HeaderTemplate>

            Items

         </HeaderTemplate>
         
         <ItemTemplate>

            <asp:LinkButton id="SelectButton" 
                 Text="Select" 
                 CommandName="Select"
                 runat="server"/>

            Item <%# DataBinder.Eval(Container.DataItem, "Item") %>

         </ItemTemplate>
              
         <SelectedItemTemplate>

            Item:
            <asp:Label id="ItemLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Item") %>' 
                 runat="server"/>

            <br>

            Quantity:
            <asp:Label id="QtyLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Qty") %>' 
                 runat="server"/>

            <br>

            Price:
            <asp:Label id="PriceLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Price", "{0:c}") %>' 
                 runat="server"/>

         </SelectedItemTemplate>

      </asp:DataList>

   </form>

</body>
</html>


[C#] 

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<html>
<head>

   <script runat="server">

      ICollection CreateDataSource() 
      {
      
         // Create sample data for the DataList control.
         DataTable dt = new DataTable();
         DataRow dr;
 
         // Define the columns of the table.
         dt.Columns.Add(new DataColumn("Item", typeof(Int32)));
         dt.Columns.Add(new DataColumn("Qty", typeof(Int32)));
         dt.Columns.Add(new DataColumn("Price", typeof(double)));
 
         // Populate the table with sample values.
         for (int i = 0; i < 9; i++) 
         {
            dr = dt.NewRow();
 
            dr[0] = i;
            dr[1] = i * 2;
            dr[2] = 1.23 * (i + 1);
 
            dt.Rows.Add(dr);
         }
 
         DataView dv = new DataView(dt);
         return dv;

      }
 
      void Page_Load(Object sender, EventArgs e) 
      {

         // Load sample data only once, when the page is first loaded.
         if (!IsPostBack) 
         {
            ItemsList.DataSource = CreateDataSource();
            ItemsList.DataBind();
         }

      }

      void Item_Command(Object sender, DataListCommandEventArgs e) 
      {
        
         // Set the SelectedIndex property to select an item in the DataList.
         ItemsList.SelectedIndex = e.Item.ItemIndex;

         // Rebind the data source to the DataList to refresh the control.
         ItemsList.DataSource = CreateDataSource();
         ItemsList.DataBind();

      }

   </script>

</head>
<body>

   <form runat="server">

      <h3>DataList Select Example</h3>

      Click <b>Select</b> to select an item.

      <br><br>
       
      <asp:DataList id="ItemsList"
           GridLines="Both"
           CellPadding="3"
           CellSpacing="0"           
           OnItemCommand="Item_Command"
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <AlternatingItemStyle BackColor="Gainsboro">
         </AlternatingItemStyle>

         <SelectedItemStyle BackColor="Yellow">
         </SelectedItemStyle>

         <HeaderTemplate>

            Items

         </HeaderTemplate>
         
         <ItemTemplate>

            <asp:LinkButton id="SelectButton" 
                 Text="Select" 
                 CommandName="Select"
                 runat="server"/>

            Item <%# DataBinder.Eval(Container.DataItem, "Item") %>

         </ItemTemplate>
              
         <SelectedItemTemplate>

            Item:
            <asp:Label id="ItemLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Item") %>' 
                 runat="server"/>

            <br>

            Quantity:
            <asp:Label id="QtyLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Qty") %>' 
                 runat="server"/>

            <br>

            Price:
            <asp:Label id="PriceLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Price", "{0:c}") %>' 
                 runat="server"/>

         </SelectedItemTemplate>

      </asp:DataList>

   </form>

</body>
</html>


[Visual Basic] 

<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<html>
<head>

   <script runat="server">

      Function CreateDataSource() As ICollection 
      
         ' Create sample data for the DataList control.
         Dim dt As DataTable = New DataTable()
         Dim dr As DataRow
 
         ' Define the columns of the table.
         dt.Columns.Add(New DataColumn("Item", GetType(Int32)))
         dt.Columns.Add(New DataColumn("Qty", GetType(Int32)))
         dt.Columns.Add(New DataColumn("Price", GetType(Double)))
 
         ' Populate the table with sample values.
         Dim i As Integer

         For i = 0 To 8 

            dr = dt.NewRow()
 
            dr(0) = i
            dr(1) = i * 2
            dr(2) = 1.23 * (i + 1)
 
            dt.Rows.Add(dr)
         
         Next i
 
         Dim dv As DataView = New DataView(dt)
         Return dv
      
      End Function
 
      Sub Page_Load(sender As Object, e As EventArgs) 

         ' Load sample data only once, when the page is first loaded.
         If Not IsPostBack Then 
         
            ItemsList.DataSource = CreateDataSource()
            ItemsList.DataBind()
         
         End If

         ' Manually register the event-handling method for the 
         ' ItemCommand event.
         AddHandler ItemsList.ItemCommand, AddressOf Item_Command

      End Sub

      Sub Item_Command(sender As Object, e As DataListCommandEventArgs) 
        
         ' Set the SelectedIndex property to select an item in the DataList.
         ItemsList.SelectedIndex = e.Item.ItemIndex

         ' Rebind the data source to the DataList to refresh the control.
         ItemsList.DataSource = CreateDataSource()
         ItemsList.DataBind()

      End Sub

   </script>

</head>
<body>

   <form runat="server">

      <h3>DataList Select Example</h3>

      Click <b>Select</b> to select an item.

      <br><br>
       
      <asp:DataList id="ItemsList"
           GridLines="Both"
           CellPadding="3"
           CellSpacing="0"           
           OnItemCommand="Item_Command"
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <AlternatingItemStyle BackColor="Gainsboro">
         </AlternatingItemStyle>

         <SelectedItemStyle BackColor="Yellow">
         </SelectedItemStyle>

         <HeaderTemplate>

            Items

         </HeaderTemplate>
         
         <ItemTemplate>

            <asp:LinkButton id="SelectButton" 
                 Text="Select" 
                 CommandName="Select"
                 runat="server"/>

            Item <%# DataBinder.Eval(Container.DataItem, "Item") %>

         </ItemTemplate>
              
         <SelectedItemTemplate>

            Item:
            <asp:Label id="ItemLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Item") %>' 
                 runat="server"/>

            <br>

            Quantity:
            <asp:Label id="QtyLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Qty") %>' 
                 runat="server"/>

            <br>

            Price:
            <asp:Label id="PriceLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Price", "{0:c}") %>' 
                 runat="server"/>

         </SelectedItemTemplate>

      </asp:DataList>

   </form>

</body>
</html>


[C#] 

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<html>
<head>

   <script runat="server">

      ICollection CreateDataSource() 
      {
      
         // Create sample data for the DataList control.
         DataTable dt = new DataTable();
         DataRow dr;
 
         // Define the columns of the table.
         dt.Columns.Add(new DataColumn("Item", typeof(Int32)));
         dt.Columns.Add(new DataColumn("Qty", typeof(Int32)));
         dt.Columns.Add(new DataColumn("Price", typeof(double)));
 
         // Populate the table with sample values.
         for (int i = 0; i < 9; i++) 
         {
            dr = dt.NewRow();
 
            dr[0] = i;
            dr[1] = i * 2;
            dr[2] = 1.23 * (i + 1);
 
            dt.Rows.Add(dr);
         }
 
         DataView dv = new DataView(dt);
         return dv;

      }
 
      void Page_Load(Object sender, EventArgs e) 
      {

         // Load sample data only once, when the page is first loaded.
         if (!IsPostBack) 
         {
            ItemsList.DataSource = CreateDataSource();
            ItemsList.DataBind();
         }

         // Manually register the event-handling method for the 
         // ItemCommand event.
         ItemsList.ItemCommand += 
             new DataListCommandEventHandler(this.Item_Command);

      }

      void Item_Command(Object sender, DataListCommandEventArgs e) 
      {
        
         // Set the SelectedIndex property to select an item in the DataList.
         ItemsList.SelectedIndex = e.Item.ItemIndex;

         // Rebind the data source to the DataList to refresh the control.
         ItemsList.DataSource = CreateDataSource();
         ItemsList.DataBind();

      }

   </script>

</head>
<body>

   <form runat="server">

      <h3>DataList Select Example</h3>

      Click <b>Select</b> to select an item.

      <br><br>
       
      <asp:DataList id="ItemsList"
           GridLines="Both"
           CellPadding="3"
           CellSpacing="0"           
           runat="server">

         <HeaderStyle BackColor="#aaaadd">
         </HeaderStyle>

         <AlternatingItemStyle BackColor="Gainsboro">
         </AlternatingItemStyle>

         <SelectedItemStyle BackColor="Yellow">
         </SelectedItemStyle>

         <HeaderTemplate>

            Items

         </HeaderTemplate>
         
         <ItemTemplate>

            <asp:LinkButton id="SelectButton" 
                 Text="Select" 
                 CommandName="Select"
                 runat="server"/>

            Item <%# DataBinder.Eval(Container.DataItem, "Item") %>

         </ItemTemplate>
              
         <SelectedItemTemplate>

            Item:
            <asp:Label id="ItemLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Item") %>' 
                 runat="server"/>

            <br>

            Quantity:
            <asp:Label id="QtyLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Qty") %>' 
                 runat="server"/>

            <br>

            Price:
            <asp:Label id="PriceLabel" 
                 Text='<%# DataBinder.Eval(Container.DataItem, "Price", "{0:c}") %>' 
                 runat="server"/>

         </SelectedItemTemplate>

      </asp:DataList>

   </form>

</body>
</html>

[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family

See Also

DataList Class | DataList Members | System.Web.UI.WebControls Namespace | ItemCommand | DataListCommandEventArgs

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