DataList.OnItemCommand(DataListCommandEventArgs) 方法
定义
引发 ItemCommand 事件。Raises the ItemCommand event. 这使你可以为事件提供自定义处理程序。This allows you to provide a custom handler for the event.
protected:
virtual void OnItemCommand(System::Web::UI::WebControls::DataListCommandEventArgs ^ e);
protected virtual void OnItemCommand (System.Web.UI.WebControls.DataListCommandEventArgs e);
abstract member OnItemCommand : System.Web.UI.WebControls.DataListCommandEventArgs -> unit
override this.OnItemCommand : System.Web.UI.WebControls.DataListCommandEventArgs -> unit
Protected Overridable Sub OnItemCommand (e As DataListCommandEventArgs)
参数
包含事件数据的 DataListCommandEventArgs。A DataListCommandEventArgs that contains event data.
示例
下面的代码示例演示如何为事件指定和编写处理程序, ItemCommand 以从控件中选择项 DataList 。The following code example demonstrates how to specify and code a handler for the ItemCommand event to select an item from the DataList control.
备注
下面的代码示例使用单文件代码模型,如果直接复制到代码隐藏文件中,则可能无法正常工作。The following code sample uses the single-file code model and may not work correctly if copied directly into a code-behind file. 必须将此代码示例复制到扩展名为 .aspx 的空文本文件中。This code sample must be copied into an empty text file that has an .aspx extension. 有关 Web 窗体代码模型的详细信息,请参阅 ASP.NET Web 窗体页代码模型。For more information on the Web Forms code model, see ASP.NET Web Forms Page Code Model.
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!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>DataList Select Example</title>
<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 id="form1" 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>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!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>DataList Select Example</title>
<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 id="form1" 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>
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!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>DataList Select Example</title>
<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 id="form1" 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>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!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>DataList Select Example</title>
<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 id="form1" 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>
注解
使用 OnItemCommand 方法可为事件提供自定义处理程序 ItemCommand 。Use the OnItemCommand method to provide a custom handler for the ItemCommand event.
ItemCommand当在控件中单击任何按钮时,将引发事件, DataList 并且通常在 CommandName 控件中具有带有自定义值(如)的按钮控件时使用 Add DataList 。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.
引发事件时,将通过委托调用事件处理程序。Raising an event invokes the event handler through a delegate. 有关详细信息,请参阅 如何:在 Web 窗体应用程序中使用事件。For more information, see How to: Consume Events in a Web Forms Application.
OnItemCommand 方法还允许派生类对事件进行处理而不必附加委托。The OnItemCommand method also allows derived classes to handle the event without attaching a delegate. 这是在派生类中处理事件的首选技术。This is the preferred technique for handling the event in a derived class.
继承者说明
在派生类中重写 OnItemCommand(DataListCommandEventArgs) 时,一定要调用基类的 OnItemCommand(DataListCommandEventArgs) 方法,以便已注册的委托对事件进行接收。When overriding OnItemCommand(DataListCommandEventArgs) in a derived class, be sure to call the base class's OnItemCommand(DataListCommandEventArgs) method so that registered delegates receive the event.