GridViewDeleteEventHandler Delegat
Definition
Wichtig
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Stellt die Methode dar, die das RowDeleting-Ereignis eines GridView-Steuerelements behandelt.
public delegate void GridViewDeleteEventHandler(System::Object ^ sender, GridViewDeleteEventArgs ^ e);public delegate void GridViewDeleteEventHandler(object sender, GridViewDeleteEventArgs e);type GridViewDeleteEventHandler = delegate of obj * GridViewDeleteEventArgs -> unitPublic Delegate Sub GridViewDeleteEventHandler(sender As Object, e As GridViewDeleteEventArgs)Parameter
- sender
- Object
Die Quelle des Ereignisses.
Ein GridViewDeleteEventArgs-Objekt, das die Ereignisdaten enthält.
Beispiele
Im folgenden Beispiel wird veranschaulicht, wie dem Ereignis eines Steuerelements programmgesteuert ein GridViewDeleteEventHandlerGridView Delegat RowDeleting hinzugefügt wird.
<%@ 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 GridView control.
GridView customersGridView = new GridView();
// Set the GridView control's properties.
customersGridView.ID = "CustomersGridView";
customersGridView.DataSourceID = "CustomersSqlDataSource";
customersGridView.AutoGenerateColumns = true;
customersGridView.AutoGenerateDeleteButton = true;
customersGridView.DataKeyNames = new String[] {"CustomerID"};
// Programmatically register the event-handling methods.
customersGridView.RowDeleting += new GridViewDeleteEventHandler(this.CustomersGridView_RowDeleting);
// Add the GridView object to the Controls collection
// of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView);
}
void CustomersGridView_RowDeleting(Object sender, GridViewDeleteEventArgs e)
{
// User the sender parameter to retrieve the GridView control
// that raised the event.
GridView customersGridView = (GridView)sender;
// Cancel the delete operation if the user attempts to remove
// the last record from the GridView control.
if (customersGridView.Rows.Count <= 1)
{
e.Cancel = true;
Message.Text = "You must keep at least one record.";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewDeleteEventHandler Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<br/>
<asp:placeholder id="GridViewPlaceHolder"
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="CustomersSqlDataSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete from Customers where CustomerID = @CustomerID"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server">
</asp:sqldatasource>
</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 GridView control.
Dim customersGridView As New GridView()
' Set the GridView control's properties.
customersGridView.ID = "CustomersGridView"
customersGridView.DataSourceID = "CustomersSqlDataSource"
customersGridView.AutoGenerateColumns = True
customersGridView.AutoGenerateDeleteButton = True
Dim keyArray() As String = {"CustomerID"}
customersGridView.DataKeyNames = keyArray
' Programmatically register the event-handling methods.
AddHandler customersGridView.RowDeleting, AddressOf CustomersGridView_RowDeleting
' Add the GridView object to the Controls collection
' of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView)
End Sub
Sub CustomersGridView_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs)
' User the sender parameter to retrieve the GridView control
' that raised the event.
Dim customersGridView As GridView = CType(sender, GridView)
' Cancel the delete operation if the user attempts to remove
' the last record from the GridView control.
If customersGridView.Rows.Count <= 1 Then
e.Cancel = True
Message.Text = "You must keep at least one record."
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewDeleteEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewDeleteEventHandler Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<br/>
<asp:placeholder id="GridViewPlaceHolder"
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="CustomersSqlDataSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
deletecommand="Delete from Customers where CustomerID = @CustomerID"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server">
</asp:sqldatasource>
</form>
</body>
</html>
Im folgenden Beispiel wird veranschaulicht, wie dem Ereignis eines Steuerelements deklarativ ein GridViewDeleteEventHandlerGridView Delegat RowDeleting hinzugefügt wird.
<%@ 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 CustomersGridView_RowDeleting
(Object sender, GridViewDeleteEventArgs e)
{
TableCell cell = CustomersGridView.Rows[e.RowIndex].Cells[2];
if (cell.Text == "Beaver")
{
e.Cancel = true;
Message.Text = "You cannot delete customer Beaver.";
}
else
{
Message.Text = "";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>GridView RowDeleting Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>
GridView RowDeleting Example
</h3>
<asp:Label ID="Message" ForeColor="Red" runat="server" />
<br />
<asp:GridView ID="CustomersGridView" runat="server"
DataSourceID="CustomersSqlDataSource"
AutoGenerateColumns="False"
AutoGenerateDeleteButton="True"
OnRowDeleting="CustomersGridView_RowDeleting"
DataKeyNames="CustomerID,AddressID">
<Columns>
<asp:BoundField DataField="FirstName"
HeaderText="FirstName" SortExpression="FirstName" />
<asp:BoundField DataField="LastName" HeaderText="LastName"
SortExpression="LastName" />
<asp:BoundField DataField="City" HeaderText="City"
SortExpression="City" />
<asp:BoundField DataField="StateProvince" HeaderText="State"
SortExpression="StateProvince" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID,
SalesLT.CustomerAddress.AddressID,
SalesLT.Customer.FirstName,
SalesLT.Customer.LastName,
SalesLT.Address.City,
SalesLT.Address.StateProvince
FROM SalesLT.Customer
INNER JOIN SalesLT.CustomerAddress
ON SalesLT.Customer.CustomerID =
SalesLT.CustomerAddress.CustomerID
INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID =
SalesLT.Address.AddressID"
DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID =
@CustomerID and AddressID = @AddressID"
ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
<DeleteParameters>
<asp:Parameter Name="AddressID" />
<asp:Parameter Name="CustomerID" />
</DeleteParameters>
</asp:SqlDataSource>
</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">
Private Sub CustomersGridView_RowDeleting _
(ByVal sender As [Object], _
ByVal e As GridViewDeleteEventArgs)
Dim cell As TableCell
cell = CustomersGridView.Rows(e.RowIndex).Cells(2)
If cell.Text = "Beaver" Then
e.Cancel = True
Message.Text = "You cannot delete customer Beaver."
Else
Message.Text = ""
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>GridView RowDeleting Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>
GridView RowDeleting Example
</h3>
<asp:Label ID="Message" ForeColor="Red" runat="server" />
<br />
<asp:GridView ID="CustomersGridView" runat="server"
DataSourceID="CustomersSqlDataSource"
AutoGenerateColumns="False"
AutoGenerateDeleteButton="True"
OnRowDeleting="CustomersGridView_RowDeleting"
DataKeyNames="CustomerID,AddressID">
<Columns>
<asp:BoundField DataField="FirstName"
HeaderText="FirstName" SortExpression="FirstName" />
<asp:BoundField DataField="LastName" HeaderText="LastName"
SortExpression="LastName" />
<asp:BoundField DataField="City" HeaderText="City"
SortExpression="City" />
<asp:BoundField DataField="StateProvince" HeaderText="State"
SortExpression="StateProvince" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID,
SalesLT.CustomerAddress.AddressID,
SalesLT.Customer.FirstName,
SalesLT.Customer.LastName,
SalesLT.Address.City,
SalesLT.Address.StateProvince
FROM SalesLT.Customer
INNER JOIN SalesLT.CustomerAddress
ON SalesLT.Customer.CustomerID =
SalesLT.CustomerAddress.CustomerID
INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID =
SalesLT.Address.AddressID"
DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID =
@CustomerID and AddressID = @AddressID"
ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
<DeleteParameters>
<asp:Parameter Name="AddressID" />
<asp:Parameter Name="CustomerID" />
</DeleteParameters>
</asp:SqlDataSource>
</form>
</body>
</html>
Hinweise
Das GridView -Steuerelement löst das RowDeleting -Ereignis aus, wenn auf eine Schaltfläche Löschen (eine Schaltfläche mit CommandName der auf "Löschen" festgelegten Eigenschaft) geklickt wird, aber bevor das GridView Steuerelement den Datensatz löscht. Dadurch können Sie eine Ereignisbehandlungsmethode bereitstellen, die eine benutzerdefinierte Routine ausführt, z. B. das Abbrechen des Löschvorgangs, wenn dieses Ereignis auftritt.
Beim Erstellen eines GridViewDeleteEventHandler-Delegaten bestimmen Sie die Methode für die Ereignisbehandlung. Um dem Ereignishandler das Ereignis zuzuordnen, fügen Sie dem Ereignis eine Instanz des Delegaten hinzu. Der Ereignishandler wird bei jedem Eintreten des Ereignisses aufgerufen, sofern der Delegat nicht entfernt wird. Weitere Informationen zu Ereignishandlerdelegaten finden Sie unter Behandeln und Auslösen von Ereignissen.
Erweiterungsmethoden
| GetMethodInfo(Delegate) |
Ruft ein Objekt ab, das die Methode darstellt, die vom angegebenen Delegaten dargestellt wird. |
Gilt für:
Weitere Informationen
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