DataList.OnItemDataBound(DataListItemEventArgs) Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Raises the ItemDataBound event. This allows you to provide a custom handler for the event.
protected:
virtual void OnItemDataBound(System::Web::UI::WebControls::DataListItemEventArgs ^ e);protected virtual void OnItemDataBound (System.Web.UI.WebControls.DataListItemEventArgs e);abstract member OnItemDataBound : System.Web.UI.WebControls.DataListItemEventArgs -> unit
override this.OnItemDataBound : System.Web.UI.WebControls.DataListItemEventArgs -> unitProtected Overridable Sub OnItemDataBound (e As DataListItemEventArgs)Parameters
A DataListItemEventArgs that contains event data.
Examples
The following code example demonstrates how to specify and code a handler for the ItemDataBound event to display the order in which items in the DataList control are bound to the control.
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 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" >
<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("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(String)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
// Populate the table with sample values.
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Description for item " + i.ToString();
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_Bound(Object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item ||
e.Item.ItemType == ListItemType.AlternatingItem)
{
// Retrieve the Label control in the current DataListItem.
Label PriceLabel = (Label)e.Item.FindControl("PriceLabel");
// Retrieve the text of the CurrencyColumn from the DataListItem
// and convert the value to a Double.
Double Price = Convert.ToDouble(
((DataRowView)e.Item.DataItem).Row.ItemArray[2].ToString());
// Format the value as currency and redisplay it in the DataList.
PriceLabel.Text = Price.ToString("c");
}
}
</script>
<head runat="server">
<title>DataList ItemDataBound Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataList ItemDataBound Example</h3>
<asp:DataList id="ItemsList"
BorderColor="black"
CellPadding="5"
CellSpacing="5"
RepeatDirection="Vertical"
RepeatLayout="Table"
RepeatColumns="3"
OnItemDataBound="Item_Bound"
runat="server">
<HeaderStyle BackColor="#aaaadd">
</HeaderStyle>
<AlternatingItemStyle BackColor="Gainsboro">
</AlternatingItemStyle>
<HeaderTemplate>
List of items
</HeaderTemplate>
<ItemTemplate>
Description: <br />
<%# DataBinder.Eval(Container.DataItem, "StringValue") %>
<br />
Price:
<asp:Label id="PriceLabel"
runat="server"/>
</ItemTemplate>
</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" >
<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("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("CurrencyValue", 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) = "Description for item " & i.ToString()
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_Bound(sender As Object, e As DataListItemEventArgs)
If e.Item.ItemType = ListItemType.Item Or _
e.Item.ItemType = ListItemType.AlternatingItem Then
' Retrieve the Label control in the current DataListItem.
Dim PriceLabel As Label = _
CType(e.Item.FindControl("PriceLabel"), Label)
' Retrieve the text of the CurrencyColumn from the DataListItem
' and convert the value to a Double.
Dim Price As Double = Convert.ToDouble( _
(CType(e.Item.DataItem, DataRowView)).Row.ItemArray(2).ToString())
' Format the value as currency and redisplay it in the DataList.
PriceLabel.Text = Price.ToString("c")
End If
End Sub
</script>
<head runat="server">
<title>DataList ItemDataBound Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataList ItemDataBound Example</h3>
<asp:DataList id="ItemsList"
BorderColor="black"
CellPadding="5"
CellSpacing="5"
RepeatDirection="Vertical"
RepeatLayout="Table"
RepeatColumns="3"
OnItemDataBound="Item_Bound"
runat="server">
<HeaderStyle BackColor="#aaaadd">
</HeaderStyle>
<AlternatingItemStyle BackColor="Gainsboro">
</AlternatingItemStyle>
<HeaderTemplate>
List of items
</HeaderTemplate>
<ItemTemplate>
Description: <br />
<%# DataBinder.Eval(Container.DataItem, "StringValue") %>
<br />
Price:
<asp:Label id="PriceLabel"
runat="server"/>
</ItemTemplate>
</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" >
<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("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(String)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
// Populate the table with sample values.
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Description for item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
DataView dv = new DataView(dt);
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
// Manually register the event-handling method for the
// ItemCommand event.
ItemsList.ItemDataBound +=
new DataListItemEventHandler(this.Item_Bound);
// Load sample data only once, when the page is first loaded.
if (!IsPostBack)
{
ItemsList.DataSource = CreateDataSource();
ItemsList.DataBind();
}
}
void Item_Bound(Object sender, DataListItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item ||
e.Item.ItemType == ListItemType.AlternatingItem)
{
// Retrieve the Label control in the current DataListItem.
Label PriceLabel = (Label)e.Item.FindControl("PriceLabel");
// Retrieve the text of the CurrencyColumn from the DataListItem
// and convert the value to a Double.
Double Price = Convert.ToDouble(
((DataRowView)e.Item.DataItem).Row.ItemArray[2].ToString());
// Format the value as currency and redisplay it in the DataList.
PriceLabel.Text = Price.ToString("c");
}
}
</script>
<head runat="server">
<title>DataList ItemDataBound Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataList ItemDataBound Example</h3>
<asp:DataList id="ItemsList"
BorderColor="black"
CellPadding="5"
CellSpacing="5"
RepeatDirection="Vertical"
RepeatLayout="Table"
RepeatColumns="3"
runat="server">
<HeaderStyle BackColor="#aaaadd">
</HeaderStyle>
<AlternatingItemStyle BackColor="Gainsboro">
</AlternatingItemStyle>
<HeaderTemplate>
List of items
</HeaderTemplate>
<ItemTemplate>
Description: <br />
<%# DataBinder.Eval(Container.DataItem, "StringValue") %>
<br />
Price:
<asp:Label id="PriceLabel"
runat="server"/>
</ItemTemplate>
</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" >
<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("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("CurrencyValue", 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) = "Description for item " & i.ToString()
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)
' Manually register the event-handling method for the
' ItemCommand event.
AddHandler ItemsList.ItemDataBound, AddressOf Item_Bound
' 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_Bound(sender As Object, e As DataListItemEventArgs)
If e.Item.ItemType = ListItemType.Item Or _
e.Item.ItemType = ListItemType.AlternatingItem Then
' Retrieve the Label control in the current DataListItem.
Dim PriceLabel As Label = _
CType(e.Item.FindControl("PriceLabel"), Label)
' Retrieve the text of the CurrencyColumn from the DataListItem
' and convert the value to a Double.
Dim Price As Double = Convert.ToDouble( _
(CType(e.Item.DataItem, DataRowView)).Row.ItemArray(2).ToString())
' Format the value as currency and redisplay it in the DataList.
PriceLabel.Text = Price.ToString("c")
End If
End Sub
</script>
<head runat="server">
<title>DataList ItemDataBound Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataList ItemDataBound Example</h3>
<asp:DataList id="ItemsList"
BorderColor="black"
CellPadding="5"
CellSpacing="5"
RepeatDirection="Vertical"
RepeatLayout="Table"
RepeatColumns="3"
OnItemDataBound="Item_Bound"
runat="server">
<HeaderStyle BackColor="#aaaadd">
</HeaderStyle>
<AlternatingItemStyle BackColor="Gainsboro">
</AlternatingItemStyle>
<HeaderTemplate>
List of items
</HeaderTemplate>
<ItemTemplate>
Description: <br />
<%# DataBinder.Eval(Container.DataItem, "StringValue") %>
<br />
Price:
<asp:Label id="PriceLabel"
runat="server"/>
</ItemTemplate>
</asp:DataList>
</form>
</body>
</html>
Remarks
Use the OnItemDataBound method to provide a custom handler for the ItemDataBound event.
The ItemDataBound event is raised after an item is data bound to the DataList control. This event provides you with the last opportunity to access the data item before it is displayed on the client. After this event is raised, the data item is no longer available.
Raising an event invokes the event handler through a delegate. For more information, see How to: Consume Events in a Web Forms Application.
The OnItemDataBound 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 OnItemDataBound(DataListItemEventArgs) in a derived class, be sure to call the base class's OnItemDataBound(DataListItemEventArgs) method so that registered delegates receive the event.
Applies to
See also
Tee yhteistyötä kanssamme GitHubissa
Tämän sisällön lähde on GitHubissa, jossa voit myös luoda ja tarkastella ongelmia ja pull-pyyntöjä. Katso lisätietoja osallistujan oppaasta.
