CommandField Konstruktor
Definition
Viktigt
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Initierar en ny instans av CommandField klassen.
public:
CommandField();public CommandField();Public Sub New ()Exempel
Följande kodexempel visar hur du använder konstruktorn för att dynamiskt lägga till en CommandField fältkolumn i en GridView kontroll.
<%@ Page language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Page_Load(Object sender, EventArgs e)
{
// Dynamically generated field columns need to be created only
// the first time the page is loaded.
if (!IsPostBack)
{
// Create a CommandField object to display a Select button
// for each record in the GridView control.
CommandField selectCommandField = new CommandField();
selectCommandField.ShowSelectButton = true;
selectCommandField.SelectText = "Select Company";
// Create a BoundField object to display the company names.
BoundField lastNameBoundField = new BoundField();
lastNameBoundField.DataField = "au_lname";
lastNameBoundField.HeaderText = "Last Name";
// Create a BoundField object to display a customer's company name.
BoundField nameBoundField = new BoundField();
nameBoundField.DataField = "CompanyName";
nameBoundField.HeaderText = "Company Name";
// Create a BoundField object to display a customer's city.
BoundField cityBoundField = new BoundField();
cityBoundField.DataField = "City";
cityBoundField.HeaderText = "City";
// Add the field columns to the ColumnFields collection of the
// GridView control.
CustomersGridView.Columns.Add(selectCommandField);
CustomersGridView.Columns.Add(nameBoundField);
CustomersGridView.Columns.Add(cityBoundField);
}
}
void CustomersGridView_SelectedIndexChanged(Object sender, EventArgs e)
{
// Get the value of the company name and city from the appropriate cells.
String companyName = CustomersGridView.SelectedRow.Cells[1].Text;
String city = CustomersGridView.SelectedRow.Cells[2].Text;
Message.Text = "You selected " + companyName + " located in " + city + ".";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>CommandField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>CommandField Constructor Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSqlDataSource"
autogeneratecolumns="False"
onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
runat="server">
</asp:gridview>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="CustomersSqlDataSource"
selectcommand="Select [CustomerID], [CompanyName], [City] From [Customers]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server">
</asp:sqldatasource>
</form>
</body>
</html>
<%@ Page language="VB" AutoEventWireup="False" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
' Dynamically generated field columns need to be created only
' the first time the page is loaded.
If Not IsPostBack Then
' Create a CommandField object to display a Select button
' for each record in the GridView control.
Dim selectCommandField As New CommandField()
selectCommandField.ShowSelectButton = True
selectCommandField.SelectText = "Select Company"
' Create a BoundField object to display the company names.
Dim lastNameBoundField As New BoundField()
lastNameBoundField.DataField = "au_lname"
lastNameBoundField.HeaderText = "Last Name"
' Create a BoundField object to display a customer's company name.
Dim nameBoundField As New BoundField()
nameBoundField.DataField = "CompanyName"
nameBoundField.HeaderText = "Company Name"
' Create a BoundField object to display a customer's city.
Dim cityBoundField As New BoundField()
cityBoundField.DataField = "City"
cityBoundField.HeaderText = "City"
' Add the field columns to the ColumnFields collection of the
' GridView control.
CustomersGridView.Columns.Add(selectCommandField)
CustomersGridView.Columns.Add(nameBoundField)
CustomersGridView.Columns.Add(cityBoundField)
End If
End Sub
Sub CustomersGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles CustomersGridView.SelectedIndexChanged
' Get the value of the company name and city from the appropriate cells.
Dim companyName As String = CustomersGridView.SelectedRow.Cells(1).Text
Dim city As String = CustomersGridView.SelectedRow.Cells(2).Text
Message.Text = "You selected " & companyName & " located in " & city & "."
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>CommandField Constructor Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>CommandField Constructor Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSqlDataSource"
autogeneratecolumns="False"
runat="server">
</asp:gridview>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Northwind sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="CustomersSqlDataSource"
selectcommand="Select [CustomerID], [CompanyName], [City] From [Customers]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server">
</asp:sqldatasource>
</form>
</body>
</html>
Kommentarer
Använd den här konstruktorn för att initiera en ny instans av CommandField klassen. Den här konstruktorn används ofta när du lägger till fält i en dynamiskt skapad databunden kontroll.
Om du vill lägga till ett CommandField fält dynamiskt i en databunden kontroll skapar du ett nytt CommandField objekt, anger dess egenskaper och lägger sedan till det i den databundna kontrollens fältsamling. Om du till exempel använder GridView kontrollen lägger du till objektet CommandField i Columns samlingen.
Note
Även om du dynamiskt kan lägga till fält i en databunden kontroll rekommenderar vi starkt att fälten deklareras statiskt och sedan visas eller döljs efter behov. Om du statiskt deklarerar alla fält minskar storleken på visningstillståndet för den överordnade databundna kontrollen.
