BaseDataList.DataKeyField Property
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.
Gets or sets the key field in the data source specified by the DataSource property.
public:
virtual property System::String ^ DataKeyField { System::String ^ get(); void set(System::String ^ value); };public virtual string DataKeyField { get; set; }[System.Web.UI.Themeable(false)]
public virtual string DataKeyField { get; set; }member this.DataKeyField : string with get, set[<System.Web.UI.Themeable(false)>]
member this.DataKeyField : string with get, setPublic Overridable Property DataKeyField As StringProperty Value
The name of the key field in the data source specified by DataSource.
- Attributes
Examples
The following code example demonstrates how to use the DataKeyField property to specify the key field for the data source.
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<!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 runat="server">
<title>BaseDataList DataKeys Example</title>
<script runat="server">
ICollection CreateDataSource()
{
// Create sample data for the DataGrid 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)));
// Define the primary key for the table as the IntegerValue
// column (column 0). To do this, first create an array of
// DataColumns to represent the primary key. The primary key can
// consist of multiple columns, but in this example, only
// one column is used.
DataColumn[] keys = new DataColumn[1];
keys[0] = dt.Columns[0];
// Then assign the array to the PrimaryKey property of the DataTable.
dt.PrimaryKey = keys;
// Populate the table with sample values.
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
// To persist the data source between posts to the server,
// store it in session state.
Session["Source"] = dt;
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)
{
ItemsGrid.DataSource = CreateDataSource();
ItemsGrid.DataBind();
}
}
void Delete_Command(Object sender, DataGridCommandEventArgs e)
{
// Retrieve the data table from session state.
DataTable dt = (DataTable)Session["Source"];
// Retrieve the data row to delete from the data table.
// Use the DataKeys property of the DataGrid control to get
// the primary key value of the selected row.
// Search the Rows collection of the data table for this value.
DataRow row;
row = dt.Rows.Find(ItemsGrid.DataKeys[e.Item.ItemIndex]);
// Delete the item selected in the DataGrid from the data source.
if(row != null)
{
dt.Rows.Remove(row);
}
// Save the data source.
Session["Source"] = dt;
// Create a DataView and bind it to the DataGrid control.
DataView dv = new DataView(dt);
ItemsGrid.DataSource = dv;
ItemsGrid.DataBind();
}
</script>
</head>
<body>
<form id="form1" runat="server">
<h3>BaseDataList DataKeys Example</h3>
<asp:DataGrid id="ItemsGrid"
BorderColor="Black"
ShowFooter="False"
CellPadding="3"
CellSpacing="0"
HeaderStyle-BackColor="#aaaadd"
DataKeyField="IntegerValue"
OnDeleteCommand="Delete_Command"
runat="server">
<Columns>
<asp:ButtonColumn Text="Delete"
CommandName="Delete"/>
</Columns>
</asp:DataGrid>
</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 runat="server">
<title>BaseDataList DataKeys and DataKeyField Example</title>
<script runat="server">
Function CreateDataSource() As ICollection
' Create sample data for the DataGrid control.
Dim dt As DataTable = New DataTable()
Dim dr As DataRow
' Define the columns of the table.
dt.Columns.Add(new DataColumn("IntegerValue", GetType(Integer)))
dt.Columns.Add(new DataColumn("StringValue", GetType(String)))
dt.Columns.Add(new DataColumn("CurrencyValue", GetType(Double)))
' Define the primary key for the table as the IntegerValue
' column (column 0). To do this, first create an array of
' DataColumns to represent the primary key. The primary key can
' consist of multiple columns, but in this example, only
' one column is used.
Dim keys(1) As DataColumn
keys(0) = dt.Columns(0)
' Then assign the array to the PrimaryKey property of the DataTable.
dt.PrimaryKey = keys
' Populate the table with sample values.
Dim i As Integer
For i = 0 To 8
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = 1.23 * (i + 1)
dt.Rows.Add(dr)
Next
' To persist the data source between posts to the server,
' store it in session state.
Session("Source") = dt
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
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub
Sub Delete_Command(sender As Object, e As DataGridCommandEventArgs)
' Retrieve the data table from session state.
Dim dt As DataTable = CType(Session("Source"), DataTable)
' Retrieve the data row to delete from the data table.
' Use the DataKeys property of the DataGrid control to get
' the primary key value of the selected row.
' Search the Rows collection of the data table for this value.
Dim row As DataRow
row = dt.Rows.Find(ItemsGrid.DataKeys(e.Item.ItemIndex))
' Delete the item selected in the DataGrid from the data source.
If Not row is Nothing Then
dt.Rows.Remove(row)
End If
' Save the data source.
Session("Source") = dt
' Create a DataView and bind it to the DataGrid control.
Dim dv As DataView = New DataView(dt)
ItemsGrid.DataSource = dv
ItemsGrid.DataBind()
End Sub
</script>
</head>
<body>
<form id="form1" runat="server">
<h3>BaseDataList DataKeys and DataKeyField Example</h3>
<asp:DataGrid id="ItemsGrid"
BorderColor="Black"
ShowFooter="False"
CellPadding="3"
CellSpacing="0"
HeaderStyle-BackColor="#aaaadd"
DataKeyField="IntegerValue"
OnDeleteCommand="Delete_Command"
runat="server">
<Columns>
<asp:ButtonColumn Text="Delete"
CommandName="Delete"/>
</Columns>
</asp:DataGrid>
</form>
</body>
</html>
Remarks
Use the DataKeyField property to specify the key field in the data source indicated by the DataSource property. The specified field is used to populate the DataKeys collection. This allows you to store the key field with a data listing control without displaying it in the control. The key field is commonly used in a handler for an event, such as ItemCommand or DeleteCommand, as part of an update query string to revise a specific record in the data source. The key field helps the update query string identify the appropriate record to modify.
This property cannot be set by themes or style sheet themes. For more information, see ThemeableAttribute and ASP.NET Themes and Skins.
Applies to
See also
Collaborate with us on GitHub
The source for this content can be found on GitHub, where you can also create and review issues and pull requests. For more information, see our contributor guide.
