DataList.SelectedIndex Property

Reference

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

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.

Gets or sets the index of the selected item in the DataList control.

public:
 virtual property int SelectedIndex { int get(); void set(int value); };

[System.ComponentModel.Bindable(true)]
public virtual int SelectedIndex { get; set; }

[<System.ComponentModel.Bindable(true)>]
member this.SelectedIndex : int with get, set

Public Overridable Property SelectedIndex As Integer

Property Value

Int32

The index of the selected item in the DataList control.

Attributes: BindableAttribute

Exceptions

ArgumentOutOfRangeException

The specified value is less than -1.

Examples

The following code example demonstrates how to use the SelectedIndex property to specify the selected item in the DataList 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" >
<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>

Remarks

Use the SelectedIndex property to programmatically specify the selected item in the DataList control. You can also use this property to determine the index of the selected item.

Note

The SelectedIndex property is zero based.

To deselect an item, set the SelectedIndex property to -1.

The SelectedIndex property is stored in control state.

Applies to

Dela via