FormViewCommandEventHandler Delegat
Definition
Wichtig
Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.
Stellt die Methode dar, die das ItemCommand Ereignis eines FormView Steuerelements behandelt. Diese Klasse kann nicht vererbt werden.
public delegate void FormViewCommandEventHandler(System::Object ^ sender, FormViewCommandEventArgs ^ e);public delegate void FormViewCommandEventHandler(object sender, FormViewCommandEventArgs e);type FormViewCommandEventHandler = delegate of obj * FormViewCommandEventArgs -> unitPublic Delegate Sub FormViewCommandEventHandler(sender As Object, e As FormViewCommandEventArgs)Parameter
- sender
- Object
Die Quelle des Ereignisses.
Ein FormViewCommandEventArgs Objekt, das die Ereignisdaten enthält.
Beispiele
Das folgende Beispiel veranschaulicht, wie Sie programmgesteuert einen FormViewCommandEventHandler Delegaten zum ItemCommand Ereignis eines FormView Steuerelements hinzufügen.
<%@ page language="C#" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
// To dynamically create a template for a FormView control,
// you must create a custom template class to represent
// the template. This template class represents the item
// template for a FormView control.
private sealed class EmployeeTemplate : ITemplate
{
// When implementing the ITemplate interface, you must
// implement the InstantiateIn method. The FormView
// control calls this method to create the template's
// content.
void ITemplate.InstantiateIn(Control container)
{
// Create the child controls contained in the template.
// For this example, the item template displays the
// FirstName and LastName fields from the data source.
// To support data binding, create event handlers
// for the DataBinding event of each child control.
// The event handlers must bind the appropriate value
// to each control.
Label firstNameLabel = new Label();
firstNameLabel.ID = "FirstNameLabel";
firstNameLabel.DataBinding += new EventHandler(FirstNameLabel_DataBinding);
LiteralControl nameLineBreak = new LiteralControl("<br/>");
LiteralControl buttonLineBreak = new LiteralControl("<br/>");
Label lastNameLabel = new Label();
lastNameLabel.ID = "LastNameLabel";
lastNameLabel.DataBinding += new EventHandler(LastNameLabel_DataBinding);
// Create a custom button control to display in the item
// template. When a button within a FormView control is
// clicked, the ItemCommand event is raised. The ItemCommand
// event is used to handle the clicking of this button.
Button displayButton = new Button();
displayButton.ID = "AddButton";
displayButton.CommandName = "Display";
displayButton.Text = "Display Employee";
// Add the controls to the Controls collection of the
// container control.
container.Controls.Add(firstNameLabel);
container.Controls.Add(nameLineBreak);
container.Controls.Add(lastNameLabel);
container.Controls.Add(buttonLineBreak);
container.Controls.Add(displayButton);
}
// This event handler binds the value of the FirstName field
// to the FirstNameLabel Label control displayed in the template.
private void FirstNameLabel_DataBinding(Object sender, EventArgs e)
{
// Use the sender parameter to retrieve the Label control
// being bound to data.
Label firstNameLabelControl = (Label)sender;
// Retrieve the value to bind to the Label control. First,
// use the NamingContainer property to retrieve the parent
// control of the Label control. In this example, the parent
// control is the FormView control.
FormView formViewContainer = (FormView)firstNameLabelControl.NamingContainer;
// Get the data item bound to the FormView control.
DataRowView rowView = (DataRowView)formViewContainer.DataItem;
// Use the data item to retrieve the value of the FirstName field.
// Set the Text property of the Label control to this value.
firstNameLabelControl.Text = rowView["FirstName"].ToString();
}
// This event handler binds the value of the LastName field
// to the LastNameLabel Label control displayed in the template.
private void LastNameLabel_DataBinding(Object sender, EventArgs e)
{
// Use the sender parameter to retrieve the Label control
// being bound to data.
Label lastNameLabelControl = (Label)sender;
// Retrieve the value to bind to the Label control. First,
// use the NamingContainer property to retrieve the parent
// control of the Label control. In this example, the parent
// control is the FormView control.
FormView formViewContainer = (FormView)lastNameLabelControl.NamingContainer;
// Get the data item bound to the FormView control.
DataRowView rowView = (DataRowView)formViewContainer.DataItem;
// Use the data item to retrieve the value of the LastName field.
// Set the Text property of the Label control to this value.
lastNameLabelControl.Text = rowView["LastName"].ToString();
}
}
void Page_Load(Object sender, EventArgs e)
{
// Create a new FormView object.
FormView employeesFormView = new FormView();
// Set the FormView object's properties.
employeesFormView.ID = "EmployeesFormView";
employeesFormView.DataSourceID = "EmployeeSource";
employeesFormView.AllowPaging = true;
employeesFormView.HeaderText = "Employee Name";
// Programmatically register the event handlers for the
// FormView control.
employeesFormView.ItemCommand += new FormViewCommandEventHandler(EmployeesFormView_ItemCommand);
employeesFormView.PageIndexChanged += new EventHandler(EmployeesFormView_PageIndexChanged);
// Create the dynamic template using the custom template class.
employeesFormView.ItemTemplate = new EmployeeTemplate();
// Add the FormView object to the Controls collection
// of the PlaceHolder control.
FormViewPlaceHolder.Controls.Add(employeesFormView);
}
void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
{
// The ItemCommand event is raised when any button within
// the FormView control is clicked. Use the CommandName property
// to determine which button was clicked.
if (e.CommandName == "Display")
{
// Use the sender parameter to get the FormView control
// that contains the button clicked.
FormView employeesFormView = (FormView)sender;
// Use the Row property to retrieve the data row.
FormViewRow row = employeesFormView.Row;
// Retrieve the FirstNameLabel and LastNameLabel Label controls
// from the data row.
Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
Label lastNameLabel = (Label)row.FindControl("LastNameLabel");
if (firstNameLabel != null && lastNameLabel != null)
{
// Display the employee's name.
MessageLabel.Text = firstNameLabel.Text + " " +
lastNameLabel.Text;
}
}
}
void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
{
// Clear the message label when the user navigates to
// a different record.
MessageLabel.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:placeholder id="FormViewPlaceHolder"
runat="server"/>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- 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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ page language="VB" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
' To dynamically create a template for a FormView control,
' you must create a custom template class to represent
' the template. This template class represents the item
' template for a FormView control.
Private NotInheritable Class EmployeeTemplate
Implements ITemplate
' When implementing the ITemplate interface, you must
' implement the InstantiateIn method. The FormView
' control calls this method to create the template's
' content.
Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn
' Create the child controls contained in the template.
' For this example, the item template displays the
' FirstName and LastName fields from the data source.
' To support data-binding, create event handlers
' for the DataBinding event of each child control.
' The event handlers must bind the appropriate value
' to each control.
Dim firstNameLabel As New Label()
firstNameLabel.ID = "FirstNameLabel"
AddHandler firstNameLabel.DataBinding, AddressOf FirstNameLabel_DataBinding
Dim nameLineBreak As New LiteralControl("<br/>")
Dim buttonLineBreak As New LiteralControl("<br/>")
Dim lastNameLabel As New Label()
lastNameLabel.ID = "LastNameLabel"
AddHandler lastNameLabel.DataBinding, AddressOf LastNameLabel_DataBinding
' Create a custom button control to display in the item
' template. When a button within a FormView control is
' clicked, the ItemCommand event is raised. The ItemCommand
' event is used to handle the clicking of this button.
Dim displayButton As New Button()
displayButton.ID = "AddButton"
displayButton.CommandName = "Display"
displayButton.Text = "Display Employee"
' Add the controls to the Controls collection of the
' container control.
container.Controls.Add(firstNameLabel)
container.Controls.Add(nameLineBreak)
container.Controls.Add(lastNameLabel)
container.Controls.Add(buttonLineBreak)
container.Controls.Add(displayButton)
End Sub
' This event handler binds the value of the FirstName field
' to the FirstNameLabel Label control displayed in the template.
Private Sub FirstNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Use the sender parameter to retrieve the Label control
' being bound to data.
Dim firstNameLabelControl As Label = CType(sender, Label)
' Retrieve the value to bind to the Label control. First,
' use the NamingContainer property to retrieve the parent
' control of the Label control. In this example, the parent
' control is the FormView control.
Dim formViewContainer As FormView = CType(firstNameLabelControl.NamingContainer, FormView)
' Get the data item bound to the FormView control.
Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)
' Use the data item to retrieve the value of the FirstName field.
' Set the Text property of the Label control to this value.
firstNameLabelControl.Text = rowView("FirstName").ToString()
End Sub
' This event handler binds the value of the LastName field
' to the LastNameLabel Label control displayed in the template.
Private Sub LastNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Use the sender parameter to retrieve the Label control
' being bound to data.
Dim lastNameLabelControl As Label = CType(sender, Label)
' Retrieve the value to bind to the Label control. First,
' use the NamingContainer property to retrieve the parent
' control of the Label control. In this example, the parent
' control is the FormView control.
Dim formViewContainer As FormView = CType(lastNameLabelControl.NamingContainer, FormView)
' Get the data item bound to the FormView control.
Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)
' Use the data item to retrieve the value of the LastName field.
' Set the Text property of the Label control to this value.
lastNameLabelControl.Text = rowView("LastName").ToString()
End Sub
End Class
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Create a new FormView object.
Dim employeesFormView As New FormView()
' Set the FormView object's properties.
employeesFormView.ID = "EmployeesFormView"
employeesFormView.DataSourceID = "EmployeeSource"
employeesFormView.AllowPaging = True
employeesFormView.HeaderText = "Employee Name"
' Programmatically register the event handlers for the
' FormView control.
AddHandler employeesFormView.ItemCommand, AddressOf EmployeesFormView_ItemCommand
AddHandler employeesFormView.PageIndexChanged, AddressOf EmployeesFormView_PageIndexChanged
' Create the dynamic template using the custom template class.
employeesFormView.ItemTemplate = New EmployeeTemplate()
' Add the FormView object to the Controls collection
' of the PlaceHolder control.
FormViewPlaceHolder.Controls.Add(employeesFormView)
End Sub
Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs)
' The ItemCommand event is raised when any button within
' the FormView control is clicked. Use the CommandName property
' to determine which button was clicked.
If e.CommandName = "Display" Then
' Use the sender parameter to get the FormView control
' that contains the button clicked.
Dim employeesFormView As FormView = CType(sender, FormView)
' Use the Row property to retrieve the data row.
Dim row As FormViewRow = employeesFormView.Row
' Retrieve the FirstNameLabel and LastNameLabel Label controls
' from the data row.
Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)
If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then
' Display the employee's name.
MessageLabel.Text = firstNameLabel.Text & " " & _
lastNameLabel.Text()
End If
End If
End Sub
Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
' Clear the message label when the user navigates to
' a different record.
MessageLabel.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:placeholder id="FormViewPlaceHolder"
runat="server"/>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- 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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Im folgenden Beispiel wird veranschaulicht, wie Sie dem Ereignis eines FormView Steuerelements deklarativ einen FormViewCommandEventHandler Delegaten ItemCommand hinzufügen.
<%@ page language="C#" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
{
// The ItemCommand event is raised when any button within
// the FormView control is clicked. Use the CommandName property
// to determine which button was clicked.
if (e.CommandName == "Display")
{
// Use the Row property to retrieve the data row.
FormViewRow row = EmployeesFormView.Row;
// Retrieve the FirstNameLabel and LastNameLabel Label controls
// from data row.
Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
Label lastNameLabel = (Label)row.FindControl("LastNameLabel");
if (firstNameLabel != null && lastNameLabel != null)
{
// Display the employee's name.
MessageLabel.Text = firstNameLabel.Text + " " +
lastNameLabel.Text;
}
}
}
void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
{
// Clear the message label when the user navigates to
// a different record.
MessageLabel.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:formview id="EmployeesFormView"
datasourceid="EmployeeSource"
allowpaging="True"
headertext="Employee Name"
onitemcommand="EmployeesFormView_ItemCommand"
onpageindexchanged="EmployeesFormView_PageIndexChanged"
runat="server">
<itemtemplate>
<asp:label id="FirstNameLabel"
text='<%# Eval("FirstName") %>'
runat="server"/>
<br/>
<asp:label id="LastNameLabel"
text='<%# Eval("LastName") %>'
runat="server"/>
<br/>
<asp:button
id="DisplayButton"
text="Display Employee"
commandname="Display"
runat="server"/>
</itemtemplate>
</asp:formview>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- 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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ page language="VB" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs) Handles EmployeesFormView.ItemCommand
' The ItemCommand event is raised when any button within
' the FormView control is clicked. Use the CommandName property
' to determine which button was clicked.
If e.CommandName = "Display" Then
' Use the Row property to retrieve the data row.
Dim row As FormViewRow = EmployeesFormView.Row
' Retrieve the FirstNameLabel and LastNameLabel Label controls
' from data row.
Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)
If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then
' Display the employee's name.
MessageLabel.Text = firstNameLabel.Text & " " & _
lastNameLabel.Text()
End If
End If
End Sub
Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles EmployeesFormView.PageIndexChanged
' Clear the message label when the user navigates to
' a different record.
MessageLabel.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:formview id="EmployeesFormView"
datasourceid="EmployeeSource"
allowpaging="True"
headertext="Employee Name"
runat="server">
<itemtemplate>
<asp:label id="FirstNameLabel"
text='<%# Eval("FirstName") %>'
runat="server"/>
<br/>
<asp:label id="LastNameLabel"
text='<%# Eval("LastName") %>'
runat="server"/>
<br/>
<asp:button
id="DisplayButton"
text="Display Employee"
commandname="Display"
runat="server"/>
</itemtemplate>
</asp:formview>
<br/><br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- 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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Hinweise
Das ItemCommand Ereignis wird ausgelöst, wenn auf eine Schaltfläche innerhalb des FormView Steuerelements geklickt wird. Auf diese Weise können Sie eine Ereignisbehandlungsmethode bereitstellen, die bei jedem Auftreten dieses Ereignisses eine benutzerdefinierte Routine ausführt.
Schaltflächen innerhalb eines FormView Steuerelements können auch einige der integrierten Funktionen des Steuerelements aufrufen. Um einen dieser Vorgänge auszuführen, legen Sie die CommandName Eigenschaft einer Schaltfläche auf einen der Werte in der folgenden Tabelle fest.
| CommandName-Wert | Beschreibung |
|---|---|
| "Abbrechen" | Bricht einen Bearbeitungs- oder Einfügevorgang ab und gibt das FormView Steuerelement an den durch die DefaultMode Eigenschaft angegebenen Modus zurück. Löst die ModeChanged Ereignisse aus ModeChanging . |
| "Löschen" | Löscht den aktuellen Datensatz. Löst die ItemDeleted Ereignisse aus ItemDeleting . |
| "Bearbeiten" | Platziert das FormView Steuerelement im Bearbeitungsmodus. Löst die ModeChanged Ereignisse aus ModeChanging . |
| "Einfügen" | Fügt den aktuellen Datensatz in die Datenquelle ein. Löst die ItemInserted Ereignisse aus ItemInserting . |
| "Neu" | Platziert das FormView Steuerelement im Einfügemodus. Löst die ModeChanged Ereignisse aus ModeChanging . |
| "Seite" | Führt einen Auslagerungsvorgang aus. Legen Sie die CommandArgument Eigenschaft der Schaltfläche auf "First", "Last", "Next", "Prev" oder eine Seitenzahl fest, um den Typ des auszuführenden Pagingvorgangs anzugeben. Löst die PageIndexChanged Ereignisse aus PageIndexChanging . |
| "Aktualisieren" | Aktualisiert den aktuellen Datensatz in der Datenquelle. Löst die ItemUpdated Ereignisse aus ItemUpdating . |
Obwohl das ItemCommand Ereignis ausgelöst wird, wenn auf eine Schaltfläche in der vorherigen Tabelle geklickt wird, empfiehlt es sich, die in der Tabelle aufgeführten Ereignisse für den Vorgang zu behandeln.
Wenn Sie einen FormViewCommandEventHandler Delegaten erstellen, identifizieren Sie die Methode, die das Ereignis behandelt. Um das Ereignis dem Ereignishandler zuzuordnen, fügen Sie dem Ereignis eine Instanz des Delegaten hinzu. Der Ereignishandler wird immer dann aufgerufen, wenn das Ereignis auftritt, es sei denn, Sie entfernen den Delegaten. Weitere Informationen zu Ereignishandlerdelegatn finden Sie unter Behandeln und Auslösen von Ereignissen.
Erweiterungsmethoden
| Name | Beschreibung |
|---|---|
| GetMethodInfo(Delegate) |
Ruft ein Objekt ab, das die vom angegebenen Delegaten dargestellte Methode darstellt. |
