DetailsViewDeleteEventHandler Delegato
Definizione
Importante
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Rappresenta il metodo che gestisce l'evento ItemDeleting di un controllo DetailsView.
public delegate void DetailsViewDeleteEventHandler(System::Object ^ sender, DetailsViewDeleteEventArgs ^ e);public delegate void DetailsViewDeleteEventHandler(object sender, DetailsViewDeleteEventArgs e);type DetailsViewDeleteEventHandler = delegate of obj * DetailsViewDeleteEventArgs -> unitPublic Delegate Sub DetailsViewDeleteEventHandler(sender As Object, e As DetailsViewDeleteEventArgs)Parametri
- sender
- Object
Origine dell'evento.
Oggetto DetailsViewDeleteEventArgs che contiene i dati dell'evento.
Esempio
Nell'esempio di codice seguente viene illustrato come aggiungere un DetailsViewDeleteEventHandler delegato a livello di codice all'evento ItemDeleting di un DetailsView controllo .
<%@ 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)
{
// Create a new DetailsView object.
DetailsView customerDetailsView = new DetailsView();
// Set the DetailsView object's properties.
customerDetailsView.ID = "CustomerDetailsView";
customerDetailsView.DataSourceID = "DetailsViewSource";
customerDetailsView.AutoGenerateRows = true;
customerDetailsView.AutoGenerateDeleteButton = true;
customerDetailsView.AllowPaging = true;
customerDetailsView.PagerSettings.Mode = PagerButtons.NextPrevious;
customerDetailsView.DataKeyNames = new String[1] { "CustomerID" };
// Programmatically register the event-handling method
// for the ItemDeleting event of a DetailsView control.
customerDetailsView.ItemDeleting += new DetailsViewDeleteEventHandler(this.CustomerDetailsView_ItemDeleting);
// Add the DetailsView object to the Controls collection
// of the PlaceHolder control.
DetailsViewPlaceHolder.Controls.Add(customerDetailsView);
}
void CustomerDetailsView_ItemDeleting(Object sender, DetailsViewDeleteEventArgs e)
{
// Get customer ID and name from the Keys and Values
// properties.
String keyValue = e.Keys["CustomerID"].ToString();
String customerName = e.Values["CompanyName"].ToString();
// Cancel the delete operation if the user attempts to
// delete protected record. In this example, records
// with a customer ID that starts with with "A" cannot
// be deleted.
if (keyValue.StartsWith("A"))
{
e.Cancel = true;
MessageLabel.Text = "You cannot delete " +
customerName + ". This customer is protected.";
}
else
{
MessageLabel.Text = "Row " + e.RowIndex.ToString() +
" deleted.";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewDeleteEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated DetailsView control. -->
<asp:PlaceHolder id="DetailsViewPlaceHolder"
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="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete [Customers]
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ page language="VB"%>
<!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)
' Create a new DetailsView object.
Dim customerDetailsView As New DetailsView()
' Set the DetailsView object's properties.
customerDetailsView.ID = "CustomerDetailsView"
customerDetailsView.DataSourceID = "DetailsViewSource"
customerDetailsView.AutoGenerateRows = True
customerDetailsView.AutoGenerateDeleteButton = True
customerDetailsView.AllowPaging = True
customerDetailsView.PagerSettings.Mode = PagerButtons.NextPrevious
Dim keyArray() As String = {"CustomerID"}
customerDetailsView.DataKeyNames = keyArray
' Programmatically register the event-handling method
' for the ItemDeleting event of a DetailsView control.
AddHandler customerDetailsView.ItemDeleting, AddressOf CustomerDetailsView_ItemDeleting
' Add the DetailsView object to the Controls collection
' of the PlaceHolder control.
DetailsViewPlaceHolder.Controls.Add(customerDetailsView)
End Sub
Sub CustomerDetailsView_ItemDeleting(ByVal sender As Object, ByVal e As DetailsViewDeleteEventArgs)
' Get customer ID and name from the Keys and Values
' properties.
Dim keyValue As String = e.Keys("CustomerID").ToString()
Dim customerName As String = e.Values("CompanyName").ToString()
' Cancel the delete operation if the user attempts to
' delete protected record. In this example, records
' with a customer ID that starts with with "A" cannot
' be deleted.
If keyValue.StartsWith("A") Then
e.Cancel = True
MessageLabel.Text = "You cannot delete " & _
customerName & ". This customer is protected."
Else
MessageLabel.Text = "Row " & e.RowIndex.ToString() & _
" deleted."
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewDeleteEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated DetailsView control. -->
<asp:PlaceHolder id="DetailsViewPlaceHolder"
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="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete [Customers]
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Nell'esempio di codice seguente viene illustrato come aggiungere in modo dichiarativo un DetailsViewDeleteEventHandler delegato all'evento ItemDeleting di un DetailsView controllo .
<%@ 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 CustomerDetailsView_ItemDeleting(Object sender,
DetailsViewDeleteEventArgs e)
{
// Get customer ID and name from the Keys and Values
// properties.
String keyValue = e.Keys["CustomerID"].ToString();
String customerName = e.Values["CompanyName"].ToString();
// Cancel the delete operation if the user attempts to
// delete protected record. In this example, records
// with a customer ID that starts with with "A" cannot
// be deleted.
if (keyValue.StartsWith("A"))
{
e.Cancel = true;
MessageLabel.Text = "You cannot delete " +
customerName + ". This customer is protected.";
}
else
{
MessageLabel.Text = "Row " + e.RowIndex.ToString() +
" deleted.";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewDeleteEventHandler Example</h3>
<asp:detailsview id="CustomerDetailsView"
datasourceid="DetailsViewSource"
autogeneraterows="true"
autogeneratedeletebutton="true"
allowpaging="true"
datakeynames="CustomerID"
onitemdeleting="CustomerDetailsView_ItemDeleting"
runat="server">
<pagersettings mode="NextPrevious"/>
</asp:detailsview>
<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="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete [Customers]
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</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 CustomerDetailsView_ItemDeleting(ByVal sender As Object, _
ByVal e As DetailsViewDeleteEventArgs) _
Handles CustomerDetailsView.ItemDeleting
' Get customer ID and name from the Keys and Values
' properties.
Dim keyValue As String = e.Keys("CustomerID").ToString()
Dim customerName As String = e.Values("CompanyName").ToString()
' Cancel the delete operation if the user attempts to
' delete protected record. In this example, records
' with a customer ID that starts with with "A" cannot
' be deleted.
If keyValue.StartsWith("A") Then
e.Cancel = True
MessageLabel.Text = "You cannot delete " & _
customerName & ". This customer is protected."
Else
MessageLabel.Text = "Row " & e.RowIndex.ToString() & _
" deleted."
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>DetailsViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DetailsViewDeleteEventHandler Example</h3>
<asp:detailsview id="CustomerDetailsView"
datasourceid="DetailsViewSource"
autogeneraterows="true"
autogeneratedeletebutton="true"
allowpaging="true"
datakeynames="CustomerID"
runat="server">
<pagersettings mode="NextPrevious"/>
</asp:detailsview>
<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="DetailsViewSource"
selectcommand="Select [CustomerID], [CompanyName], [Address],
[City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete [Customers]
Where [CustomerID]=@CustomerID"
connectionstring=
"<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Commenti
Il DetailsView controllo genera l'evento ItemDeleting quando si fa clic su un pulsante Elimina (un pulsante con la relativa CommandName proprietà impostata su "Elimina") all'interno del controllo, ma dopo che il DetailsView controllo elimina il record. In questo modo è possibile fornire un gestore eventi che esegue una routine personalizzata, ad esempio il controllo dei risultati di un'operazione di eliminazione, ogni volta che si verifica questo evento.
Quando si crea un delegato DetailsViewDeleteEventHandler, si identifica il metodo che gestirà l'evento. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato. Per altre informazioni sui delegati del gestore eventi, vedere Gestione e generazione di eventi.
Metodi di estensione
| GetMethodInfo(Delegate) |
Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato. |
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