DataGridColumnCollection.RemoveAt(Int32) 方法
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。
從 DataGridColumn 集合中指定的索引處，移除 DataGridColumnCollection 衍生資料行物件。
public:
void RemoveAt(int index);public void RemoveAt (int index);member this.RemoveAt : int -> unitPublic Sub RemoveAt (index As Integer)參數
- index
- Int32
在 DataGridColumn 中，要移除之 DataGridColumnCollection 衍生資料行的索引。
例外狀況
index 小於 0 或大於 Count。
範例
下列程式碼範例示範如何使用 RemoveAt 方法來從 DataGridColumnCollection 集合中移除資料行。 請注意， Columns 控制項的 DataGrid 屬性是 DataGridColumnCollection 集合。
<%@ 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 language="C#" runat="server">
DataTable Cart;
DataView CartView;
ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;
dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
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);
}
DataView dv = new DataView(dt);
return dv;
}
void Page_Load(Object sender, EventArgs e)
{
if (Session["DG4_ShoppingCart"] == null)
{
Cart = new DataTable();
Cart.Columns.Add(new DataColumn("Item", typeof(string)));
Cart.Columns.Add(new DataColumn("Price", typeof(string)));
Session["DG4_ShoppingCart"] = Cart;
}
else
{
Cart = (DataTable)Session["DG4_ShoppingCart"];
}
CartView = new DataView(Cart);
ShoppingCart.DataSource = CartView;
ShoppingCart.DataBind();
if (!IsPostBack)
{
// Load this data only once.
ItemsGrid.DataSource= CreateDataSource();
ItemsGrid.DataBind();
}
}
void Grid_CartCommand(Object sender, DataGridCommandEventArgs e) {
DataRow dr = Cart.NewRow();
// e.Item is the table row where the command is raised.
// For bound columns, the value is stored in the Text property of the TableCell.
TableCell itemCell = e.Item.Cells[2];
TableCell priceCell = e.Item.Cells[3];
string item = itemCell.Text;
string price = priceCell.Text;
if (((Button)e.CommandSource).CommandName == "AddToCart")
{
dr[0] = item;
dr[1] = price;
Cart.Rows.Add(dr);
}
else
{
//Remove from Cart.
CartView.RowFilter = "Item='" + item + "'";
if (CartView.Count > 0)
{
CartView.Delete(0);
}
CartView.RowFilter = "";
}
ShoppingCart.DataBind();
}
void Page_Init(Object sender, EventArgs e)
{
ItemsGrid.Columns.RemoveAt(2);
}
</script>
<head runat="server">
<title>DataGridColumnCollection RemoveAt Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGridColumnCollection RemoveAt Example</h3>
<table cellpadding="5">
<tr valign="top">
<td>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
OnItemCommand="Grid_CartCommand"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:ButtonColumn
HeaderText="Add to cart"
ButtonType="PushButton"
Text="Add"
CommandName="AddToCart"/>
<asp:ButtonColumn
HeaderText="Remove from cart"
ButtonType="PushButton"
Text="Remove"
CommandName="RemoveFromCart"/>
<asp:BoundColumn
HeaderText="Item Number"
DataField="IntegerValue"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</td>
<td>
<b>Shopping Cart</b>
<asp:DataGrid id="ShoppingCart"
runat="server"
BorderColor="black"
BorderWidth="1"
GridLines="Both"
ShowFooter="false"
CellPadding="3"
CellSpacing="0">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
</asp:DataGrid>
</td>
</tr>
</table>
</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 language="VB" runat="server">
Dim Cart As DataTable
Dim CartView As DataView
Function CreateDataSource() As ICollection
Dim dt As New DataTable()
Dim dr As DataRow
dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("CurrencyValue", GetType(Double)))
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 i
Dim dv As New DataView(dt)
Return dv
End Function 'CreateDataSource
Sub Page_Load(sender As Object, e As EventArgs)
If Session("DG4_ShoppingCart") Is Nothing Then
Cart = New DataTable()
Cart.Columns.Add(New DataColumn("Item", GetType(String)))
Cart.Columns.Add(New DataColumn("Price", GetType(String)))
Session("DG4_ShoppingCart") = Cart
Else
Cart = CType(Session("DG4_ShoppingCart"), DataTable)
End If
CartView = New DataView(Cart)
ShoppingCart.DataSource = CartView
ShoppingCart.DataBind()
If Not IsPostBack Then
' Load this data only once
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub 'Page_Load
Sub Grid_CartCommand(sender As Object, e As DataGridCommandEventArgs)
Dim dr As DataRow = Cart.NewRow()
' e.Item is the table row where the command is raised.
' For bound columns, the value is stored in the Text property of the TableCell.
Dim itemCell As TableCell = e.Item.Cells(2)
Dim priceCell As TableCell = e.Item.Cells(3)
Dim item As String = itemCell.Text
Dim price As String = priceCell.Text
If CType(e.CommandSource, Button).CommandName = "AddToCart" Then
dr(0) = item
dr(1) = price
Cart.Rows.Add(dr)
Else
'Remove from Cart.
CartView.RowFilter = "Item='" & item & "'"
If CartView.Count > 0 Then
CartView.Delete(0)
End If
CartView.RowFilter = ""
End If
ShoppingCart.DataBind()
End Sub 'Grid_CartCommand
Sub Page_Init(sender As Object, e As EventArgs)
ItemsGrid.Columns.RemoveAt(2)
End Sub 'Page_Init
</script>
<head runat="server">
<title>DataGridColumnCollection RemoveAt Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGridColumnCollection RemoveAt Example</h3>
<table cellpadding="5">
<tr valign="top">
<td>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
OnItemCommand="Grid_CartCommand"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:ButtonColumn
HeaderText="Add to cart"
ButtonType="PushButton"
Text="Add"
CommandName="AddToCart"/>
<asp:ButtonColumn
HeaderText="Remove from cart"
ButtonType="PushButton"
Text="Remove"
CommandName="RemoveFromCart"/>
<asp:BoundColumn
HeaderText="Item Number"
DataField="IntegerValue"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</td>
<td>
<b>Shopping Cart</b>
<asp:DataGrid id="ShoppingCart"
runat="server"
BorderColor="black"
BorderWidth="1"
GridLines="Both"
ShowFooter="false"
CellPadding="3"
CellSpacing="0">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</html>
備註
使用這個方法可從集合中移除 DataGridColumn 位於指定索引處的衍生資料行物件 DataGridColumnCollection 。
控制項 DataGrid 不會將其集合的內容 Columns 儲存在檢視狀態中。 若要動態新增或移除資料行，您必須在每次重新整理頁面時，以程式設計方式新增或移除資料行。 提供函 Page_Init 式，在控制項可以重載其狀態並重建本身之前 DataGrid ，先新增或移除資料行。 否則，當集合顯示時，集合的 Columns 變更不會反映在 DataGrid 控制項中。
