CommandField Konstruktor
Definition
Wichtig
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Initialisiert eine neue Instanz der CommandField-Klasse.
public:
CommandField();public CommandField ();Public Sub New ()Beispiele
Im folgenden Codebeispiel wird veranschaulicht, wie der Konstruktor dynamisch eine CommandField Feldspalte zu einem GridView Steuerelement hinzufügen kann.
<%@ 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>
Hinweise
Verwenden Sie diesen Konstruktor, um eine neue Instanz der CommandField Klasse zu initialisieren. Dieser Konstruktor wird häufig verwendet, wenn Felder zu einem dynamisch erstellten datengebundenen Steuerelement hinzugefügt werden.
Zum dynamischen Hinzufügen eines Felds zu einem datengebundenen Steuerelement erstellen Sie ein CommandField neues CommandField Objekt, legen Sie ihre Eigenschaften fest, und fügen Sie es dann der Feldsammlung des datengebundenen Steuerelements hinzu. Wenn Sie beispielsweise das Steuerelement verwenden, fügen Sie das GridView CommandField Objekt der Columns Auflistung hinzu.
Hinweis
Obwohl Sie Felder dynamisch zu einem datengebundenen Steuerelement hinzufügen können, wird dringend empfohlen, dass Felder nach Bedarf deklariert und dann ausgeblendet oder angezeigt werden. Das Deklarieren aller Felder reduziert die Größe des Ansichtszustands für das übergeordnete datengebundene Steuerelement.