BaseDataList.DataKeyField BaseDataList.DataKeyField BaseDataList.DataKeyField BaseDataList.DataKeyField Property

Определение

Получает или задает ключевое поле источника данных, указанного в свойстве DataSource.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); };
[System.Web.UI.Themeable(false)]
public virtual string DataKeyField { get; set; }
member this.DataKeyField : string with get, set
Public Overridable Property DataKeyField As String

Значение свойства

Имя ключевого поля источника данных, указанного в свойстве DataSource.The name of the key field in the data source specified by DataSource.

Примеры

В следующем примере кода демонстрируется использование DataKeyField свойство, чтобы указать поле ключа для источника данных.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>

Комментарии

Используйте DataKeyField свойство, чтобы указать ключевое поле в источнике данных обозначаются DataSource свойство.Use the DataKeyField property to specify the key field in the data source indicated by the DataSource property. Указанное поле используется для заполнения DataKeys коллекции.The specified field is used to populate the DataKeys collection. Это позволяет хранить ключевого поля с данными, элемента управления списка без его отображения в элементе управления.This allows you to store the key field with a data listing control without displaying it in the control. Ключевое поле обычно используется в обработчике для события, такие как ItemCommand или DeleteCommand, как часть строки запроса на обновление для изменения конкретной записи в источнике данных.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. Поле ключа помогает определить соответствующую запись для изменения строки запроса update.The key field helps the update query string identify the appropriate record to modify.

Значение для данного свойства нельзя задать с помощью тем или тем таблиц стилей.This property cannot be set by themes or style sheet themes. Дополнительные сведения см. в разделе ThemeableAttribute и тем и оформлений ASP.NET.For more information, see ThemeableAttribute and ASP.NET Themes and Skins.

Применяется к

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