DataGrid.VirtualItemCount 屬性
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
在使用自訂分頁時，取得或設定 DataGrid 控制項中項目的虛擬數目。
public:
virtual property int VirtualItemCount { int get(); void set(int value); };[System.ComponentModel.Browsable(false)]
public virtual int VirtualItemCount { get; set; }[<System.ComponentModel.Browsable(false)>]
member this.VirtualItemCount : int with get, setPublic Overridable Property VirtualItemCount As Integer屬性值
在使用自訂分頁時，DataGrid 控制項中項目的虛擬數目。
- 屬性
例外狀況
指定的值為負數。
範例
下列程式碼範例示範如何在使用自訂分頁時，使用 VirtualItemCount 屬性來指定 控制項中的 DataGrid 專案總數。
<%@ 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">
// Normally, an entire data source is loaded in the DataGrid control,
// which can take up a lot of resources. This example uses custom
// paging, which loads only the segment of data needed to fill a
// single page. In order to query for the appropriate segment of
// data, the index of the first item displayed on a page must be
// tracked as the user navigates between pages.
int startIndex = 0;
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("DateTimeValue", typeof(string)));
dt.Columns.Add(new DataColumn("BoolValue", typeof(bool)));
// Populate the table with sample values. When using custom paging,
// a query should only return enough data to fill a single page,
// beginning at the start index.
for (int i = startIndex; i < (startIndex + MyDataGrid.PageSize); i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = DateTime.Now.ToShortDateString();
dr[3] = (i % 2 != 0) ? true : false;
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)
{
// Set the virtual item count, which specifies the total number
// items displayed in the DataGrid control when custom paging
// is used.
MyDataGrid.VirtualItemCount = 200;
// Retrieve the segment of data to display on the page from the
// data source and bind it to the DataGrid control.
BindGrid();
}
}
void MyDataGrid_Page(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.
MyDataGrid.CurrentPageIndex = e.NewPageIndex;
// Calculate the index of the first item to display on the page
// using the current page index and the page size.
startIndex = MyDataGrid.CurrentPageIndex * MyDataGrid.PageSize;
// Retrieve the segment of data to display on the page from the
// data source and bind it to the DataGrid control.
BindGrid();
}
void BindGrid()
{
MyDataGrid.DataSource = CreateDataSource();
MyDataGrid.DataBind();
}
</script>
<head runat="server">
<title> DataGrid Custom Paging Example </title>
</head>
<body>
<form id="form1" runat="server">
<h3> DataGrid Custom Paging Example </h3>
<asp:DataGrid id="MyDataGrid"
AllowCustomPaging="True"
AllowPaging="True"
PageSize="10"
OnPageIndexChanged="MyDataGrid_Page"
runat="server">
<HeaderStyle BackColor="Navy"
ForeColor="White"
Font-Bold="True" />
<PagerStyle Mode="NumericPages"
HorizontalAlign="Right" />
</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" >
<script runat="server">
' Normally, an entire data source is loaded in the DataGrid control,
' which can take up a lot of resources. This example uses custom
' paging, which loads only the segment of data needed to fill a
' single page. In order to query for the appropriate segment of
' data, the index of the first item displayed on a page must be
' tracked as the user navigates between pages.
Dim startIndex As Integer = 0
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(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("DateTimeValue", GetType(String)))
dt.Columns.Add(New DataColumn("BoolValue", GetType(Boolean)))
' Populate the table with sample values. When using custom paging,
' a query should only return enough data to fill a single page,
' beginning at the start index.
Dim i As Integer
For i = startIndex To ((startIndex + MyDataGrid.PageSize) - 1)
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " & i.ToString()
dr(2) = DateTime.Now.ToShortDateString()
If (i Mod 2 <> 0) Then
dr(3) = True
Else
dr(3) = False
End If
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
' Set the virtual item count, which specifies the total number
' items displayed in the DataGrid control when custom paging
' is used.
MyDataGrid.VirtualItemCount = 200
' Retrieve the segment of data to display on the page from the
' data source and bind it to the DataGrid control.
BindGrid()
End If
End Sub
Sub MyDataGrid_Page(sender as Object, e As DataGridPageChangedEventArgs)
' 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.
MyDataGrid.CurrentPageIndex = e.NewPageIndex
' Calculate the index of the first item to display on the page
' using the current page index and the page size.
startIndex = MyDataGrid.CurrentPageIndex * MyDataGrid.PageSize
' Retrieve the segment of data to display on the page from the
' data source and bind it to the DataGrid control.
BindGrid()
End Sub
Sub BindGrid()
MyDataGrid.DataSource = CreateDataSource()
MyDataGrid.DataBind()
End Sub
</script>
<head runat="server">
<title> DataGrid Custom Paging Example </title>
</head>
<body>
<form id="form1" runat="server">
<h3> DataGrid Custom Paging Example </h3>
<asp:DataGrid id="MyDataGrid"
AllowCustomPaging="True"
AllowPaging="True"
PageSize="10"
OnPageIndexChanged="MyDataGrid_Page"
runat="server">
<HeaderStyle BackColor="Navy"
ForeColor="White"
Font-Bold="True" />
<PagerStyle Mode="NumericPages"
HorizontalAlign="Right" />
</asp:DataGrid>
</form>
</body>
</html>
備註
使用這個屬性可指定使用自訂分頁時控制項中的 DataGrid 虛擬專案數。 只有當 屬性設定為 true 時， AllowCustomPaging 才會使用這個屬性。
AllowCustomPaging如果 屬性設定 true 為 ，則會根據 和 VirtualItemCount 屬性的值 PageSize 計算控制項中 DataGrid 顯示每個專案所需的頁數。
AllowCustomPaging如果 屬性設定 false 為 ，則會根據 屬性的值 PageSize 和資料來源中的專案總數，計算控制項中顯示的 DataGrid 頁數。
