DataGridColumnCollection.Clear Method ()
.NET Framework (current version)
Removes all DataGridColumn-derived column objects from the DataGridColumnCollection collection.
Assembly: System.Web (in System.Web.dll)
Use this method to remove all DataGridColumn-derived column objects from the DataGridColumnCollection collection.
Note |
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The Count property is automatically set to 0 after this method is used. |
The following code example demonstrates how to use the Clear method to empty the DataGridColumnCollection collection before adding new columns to the collection.
<%@ 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"> 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_Init(sender As Object, e As EventArgs) ' Empty DataGridColumnsCollection collection. ItemsGrid.Columns.Clear() ' Create dynamic columns to add to Columns collection. Dim IntegerColumn As New BoundColumn() Dim StringColumn As New BoundColumn() Dim PriceColumn As New BoundColumn() IntegerColumn.HeaderText = "Item Number" IntegerColumn.DataField = "IntegerValue" StringColumn.HeaderText = "Item" StringColumn.DataField = "StringValue" PriceColumn.HeaderText = "Price" PriceColumn.DataField = "CurrencyValue" ' Add columns to Columns collection. ItemsGrid.Columns.Add(IntegerColumn) ItemsGrid.Columns.Add(StringColumn) ItemsGrid.Columns.Add(PriceColumn) End Sub 'Page_Init Sub Page_Load(sender As Object, e As EventArgs) If Not IsPostBack Then ' Load this data only once ItemsGrid.DataSource = CreateDataSource() ItemsGrid.DataBind() End If End Sub 'Page_Load </script> <head runat="server"> <title>DataGridColumnCollection Clear Example</title> </head> <body> <form id="form1" runat="server"> <h3>DataGridColumnCollection Clear Example</h3> <b>Product List</b> <asp:DataGrid id="ItemsGrid" BorderColor="black" BorderWidth="1" CellPadding="3" AutoGenerateColumns="false" runat="server"> <HeaderStyle BackColor="#00aaaa"> </HeaderStyle> <Columns> <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> </form> </body> </html>
.NET Framework
Available since 1.1
Available since 1.1
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