DataListItemEventHandler Delegate
Represents the method that will handle the ItemCreated and ItemDataBound events of the DataList control.
[Visual Basic] <Serializable> Public Delegate Sub DataListItemEventHandler( _ ByVal sender As Object, _ ByVal e As DataListItemEventArgs _ ) [C#] [Serializable] public delegate void DataListItemEventHandler( object sender, DataListItemEventArgs e ); [C++] [Serializable] public __gc __delegate void DataListItemEventHandler( Object* sender, DataListItemEventArgs* e );
[JScript] In JScript, you can use the delegates in the .NET Framework, but you cannot define your own.
Parameters [Visual Basic, C#, C++]
The declaration of your event handler must have the same parameters as the DataListItemEventHandler delegate declaration.
- sender
- The source of the event.
- e
- A DataListItemEventArgs that contains the event data.
Remarks
The ItemCreated event is raised when an item in the DataList control is created.
The ItemDataBound event is raised when an item in the DataList control is data bound to a source.
When you create a DataListItemEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Events and Delegates.
Example
[Visual Basic, C#] The following example demonstrates how to specify and code a handler for the ItemCreated event to display the order in which items in the DataList are created.
[Visual Basic] <%@ Page Language="VB" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <script language = "VB" runat="server"> Function CreateDataSource() As ICollection Dim dt As New DataTable() Dim dr As DataRow dt.Columns.Add(New DataColumn("StringValue", GetType(String))) Dim i As Integer For i = 0 To 19 dr = dt.NewRow() dr(0) = "Item " & i.ToString() dt.Rows.Add(dr) Next i Dim dv As New DataView(dt) Return dv End Function 'CreateDataSource Sub Page_Load(sender As Object, e As EventArgs) If Not IsPostBack Then DataList1.DataSource = CreateDataSource() DataList1.DataBind() End If End Sub 'Page_Load Sub Item_Created(sender As Object, e As DataListItemEventArgs) Label1.Text = Label1.Text & " " & e.Item.ItemIndex.ToString() End Sub 'Item_Created </script> <body> <form runat=server> <asp:DataList id="DataList1" RepeatLayout="Table" RepeatDirection="Horizontal" RepeatColumns="5" GridLines="Both" OnItemCreated="Item_Created" runat="server"> <HeaderTemplate> Items </HeaderTemplate> <ItemTemplate> <%# DataBinder.Eval(Container.DataItem, "StringValue") %> </ItemTemplate> </asp:DataList> <p> <hr noshade align="left" width="300px"> <asp:Label id="Label1" Text="Order Items Created: " runat="server"/> <br> Note: -1 refers to the header being created. </form> </body> </html> [C#] <%@ Page Language="C#" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <script language = "C#" runat="server"> ICollection CreateDataSource() { DataTable dt = new DataTable(); DataRow dr; dt.Columns.Add(new DataColumn("StringValue", typeof(string))); for (int i = 0; i < 20; i++) { dr = dt.NewRow(); dr[0] = "Item " + i.ToString(); dt.Rows.Add(dr); } DataView dv = new DataView(dt); return dv; } void Page_Load(Object sender, EventArgs e) { if (!IsPostBack) { DataList1.DataSource = CreateDataSource(); DataList1.DataBind(); } } void Item_Created(Object sender, DataListItemEventArgs e) { Label1.Text = Label1.Text + " " + e.Item.ItemIndex.ToString(); } </script> <body> <form runat=server> <asp:DataList id="DataList1" RepeatLayout="Table" RepeatDirection="Horizontal" RepeatColumns="5" GridLines="Both" OnItemCreated="Item_Created" runat="server"> <HeaderTemplate> Items </HeaderTemplate> <ItemTemplate> <%# DataBinder.Eval(Container.DataItem, "StringValue") %> </ItemTemplate> </asp:DataList> <p> <hr noshade align="left" width="300px"> <asp:Label id="Label1" Text="Order Items Created: " runat="server"/> <br> Note: -1 refers to the header being created. </form> </body> </html> [Visual Basic] <%@ Page Language="VB" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <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> <body> <form runat=server> <h3>DataList ItemDataBound Example</h3> <asp:DataList id="ItemsList" BorderColor="black" CellPadding="5" CellSpacing="5" RepeatDirection="Vertical" RepeatLayout="Table" RepeatColumns="3" ShowBorder="True" 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> [C#] <%@ Page Language="C#" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <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> <body> <form runat=server> <h3>DataList ItemDataBound Example</h3> <asp:DataList id="ItemsList" BorderColor="black" CellPadding="5" CellSpacing="5" RepeatDirection="Vertical" RepeatLayout="Table" RepeatColumns="3" ShowBorder="True" 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> [Visual Basic] <%@ Page Language="VB" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <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> <body> <form runat=server> <h3>DataList ItemDataBound Example</h3> <asp:DataList id="ItemsList" BorderColor="black" CellPadding="5" CellSpacing="5" RepeatDirection="Vertical" RepeatLayout="Table" RepeatColumns="3" ShowBorder="True" 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> [C#] <%@ Page Language="C#" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <html> <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> <body> <form runat=server> <h3>DataList ItemDataBound Example</h3> <asp:DataList id="ItemsList" BorderColor="black" CellPadding="5" CellSpacing="5" RepeatDirection="Vertical" RepeatLayout="Table" RepeatColumns="3" ShowBorder="True" 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>
[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button
in the upper-left corner of the page.
Requirements
Namespace: System.Web.UI.WebControls
Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family
Assembly: System.Web (in System.Web.dll)
See Also
System.Web.UI.WebControls Namespace | DataListItemEventArgs | DataList | ItemCreated | ItemDataBound