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Evento DataGrid.PageIndexChanged

 

Data di pubblicazione: ottobre 2016

Si verifica quando viene fatto clic su uno degli elementi di selezione della pagina.

Spazio dei nomi:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

public event DataGridPageChangedEventHandler PageIndexChanged

Il PageIndexChanged evento viene generato quando viene fatto clic su uno degli elementi di selezione della pagina.

Un tipico gestore per il PageIndexChanged set di eventi di CurrentPageIndex proprietà all'indice di pagina che si desidera visualizzare e quindi utilizza il DataBind metodo per associare i dati per il DataGrid controllo.

Per ulteriori informazioni sulla gestione degli eventi, vedere NIB: utilizzo degli eventi.

Esempio di codice riportato di seguito viene illustrato come specificare e codificare un gestore per il PageIndexChanged evento. Visualizza le pagine di DataGrid controllo in incrementi di 10 elementi.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    private 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)));

        // Populate the table with sample values.
        for (int i = 0; i <= 100; i++) 
        {
            dr = dt.NewRow();
            dr[0] = i;
            dr[1] = "Item " + i.ToString();
            dr[2] = 1.23 * (i + 1);

            dt.Rows.Add(dr);
        }
        DataView dv = new DataView(dt);
        return dv;
    }

    private 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();
        }
    }

    private void Check_Change(Object sender, EventArgs e)
    {
        // Allow or prevent paging depending 
        // on the user's selection.
        ItemsGrid.AllowPaging = AllowPagingCheckBox.Checked;

        // Rebind the data to refresh the DataGrid control. 
        ItemsGrid.DataSource = CreateDataSource();
        ItemsGrid.DataBind();
    }

    private void Grid_Change(Object sender, DataGridPageChangedEventArgs e) 
    {
        // For the DataGrid control to navigate to the correct page when
        // paging is allowed, the CurrentPageIndex property must be updated
        // programmatically. This process is usually accomplished in the
        // event-handling method for the PageIndexChanged event.

        // Set CurrentPageIndex to the page the user clicked.
        ItemsGrid.CurrentPageIndex = e.NewPageIndex;

        // Rebind the data to refresh the DataGrid control. 
        ItemsGrid.DataSource = CreateDataSource();
        ItemsGrid.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>DataGrid AllowPaging Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <h3>DataGrid AllowPaging Example</h3>

    <p>Select whether to allow paging in the DataGrid control.<br />
       <asp:CheckBox id="AllowPagingCheckBox"
            Text="Allow paging"
            AutoPostBack="True"
            Checked="True"
            OnCheckedChanged="Check_Change"
            runat="server" />
    </p>
    <hr />
    <asp:Label runat="server" 
        AssociatedControlID="ItemsGrid" 
        Font-Bold="true">Product List</asp:Label>
    <asp:DataGrid id="ItemsGrid" runat="server"
        BorderColor="Gray"
        BorderWidth="1"
        CellPadding="3"
        AutoGenerateColumns="False"
        UseAccessibleHeader="true"
        PageSize="10"
        AllowPaging="True"
        OnPageIndexChanged="Grid_Change">

        <HeaderStyle BackColor="LightBlue" />
        <Columns>
            <asp:BoundColumn DataField="IntegerValue" 
                 SortExpression="IntegerValue"
                 ItemStyle-HorizontalAlign="center"
                 HeaderText="Item" />

            <asp:BoundColumn DataField="StringValue" 
                HeaderText="Description" 
                ItemStyle-HorizontalAlign="left"
                SortExpression="StringValue" />

            <asp:BoundColumn DataField="CurrencyValue" 
                 HeaderText="Price"
                 SortExpression="CurrencyValue"
                 DataFormatString="{0:c}" />

        </Columns>
        <ItemStyle HorizontalAlign="Right" />
    </asp:DataGrid>

    </div>
    </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 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)));

         // Populate the table with sample values.
         for (int i=0; i<=100; i++) 
         {

            dr = dt.NewRow();

            dr[0] = i;
            dr[1] = "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)
         { 

            ItemsGrid.DataSource = CreateDataSource();
            ItemsGrid.DataBind();

         }

         // Manually register the event-handling method for the PageIndexChanged  
         // event of the DataGrid control.
         ItemsGrid.PageIndexChanged += new DataGridPageChangedEventHandler(this.Grid_Change);

      }

      void Check_Change(Object sender, EventArgs e)
      {

         // Allow or prevent paging depending on the user's selection.
         if (AllowPagingCheckBox.Checked)
         {

            ItemsGrid.AllowPaging = true;

         }
         else
         {

            ItemsGrid.AllowPaging = false;

         }

         // Re-bind the data to refresh the DataGrid control. 
         ItemsGrid.DataSource = CreateDataSource();
         ItemsGrid.DataBind();

      }

      void Grid_Change(Object sender, DataGridPageChangedEventArgs e) 
      {

         // For the DataGrid control to navigate to the correct page when paging is
         // allowed, the CurrentPageIndex property must be programmatically updated.
         // This process is usually accomplished in the event-handling method for the
         // PageIndexChanged event.

         // Set CurrentPageIndex to the page the user clicked.
         ItemsGrid.CurrentPageIndex = e.NewPageIndex;

         // Re-bind the data to refresh the DataGrid control. 
         ItemsGrid.DataSource = CreateDataSource();
         ItemsGrid.DataBind();

      }

   </script>

<head runat="server">
    <title>DataGrid PageIndexChanged Example</title>
</head>
<body>

   <form id="form1" runat="server">

      <h3>DataGrid PageIndexChanged Example</h3>

      Select whether to allow paging in the DataGrid control.

      <br /><br />

      <b>Product List</b>

      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           AutoGenerateColumns="False"
           PageSize="10"
           AllowPaging="True"
           runat="server">

         <HeaderStyle BackColor="#00aaaa">
         </HeaderStyle>

         <Columns>

            <asp:BoundColumn DataField="IntegerValue" 
                 SortExpression="IntegerValue"
                 HeaderText="Item"/>

            <asp:BoundColumn DataField="StringValue"
                 SortExpression="StringValue" 
                 HeaderText="Description"/>

            <asp:BoundColumn DataField="CurrencyValue" 
                 HeaderText="Price"
                 SortExpression="CurrencyValue"
                 DataFormatString="{0:c}">

               <ItemStyle HorizontalAlign="Right">
               </ItemStyle>

            </asp:BoundColumn>

         </Columns> 

      </asp:DataGrid>

      <hr />

      <table cellpadding="5">

         <tr>

            <td>

               <asp:CheckBox id="AllowPagingCheckBox"
                    Text="Allow paging"
                    AutoPostBack="True"
                    Checked="True"
                    OnCheckedChanged="Check_Change"
                    runat="server"/>

            </td>

         </tr>

      </table>

   </form>

</body>
</html>

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