GridViewPageEventHandler Delegato
Definizione
Importante
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Rappresenta il metodo che gestisce l'evento PageIndexChanging di un controllo GridView.
public delegate void GridViewPageEventHandler(System::Object ^ sender, GridViewPageEventArgs ^ e);public delegate void GridViewPageEventHandler(object sender, GridViewPageEventArgs e);type GridViewPageEventHandler = delegate of obj * GridViewPageEventArgs -> unitPublic Delegate Sub GridViewPageEventHandler(sender As Object, e As GridViewPageEventArgs)Parametri
- sender
- Object
Origine dell'evento.
Oggetto GridViewPageEventArgs contenente i dati dell'evento.
Esempio
Nell'esempio seguente viene illustrato come aggiungere un GridViewPageEventHandler delegato a livello di codice all'evento PageIndexChanging di un GridView 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 GridView control.
GridView customersGridView = new GridView();
// Set the GridView object's properties.
customersGridView.ID = "CustomersGridView";
customersGridView.DataSourceID = "CustomersSource";
customersGridView.AutoGenerateColumns = true;
customersGridView.EmptyDataText = "No data available.";
customersGridView.AllowPaging = true;
customersGridView.AutoGenerateEditButton = true;
customersGridView.PagerSettings.Mode = PagerButtons.Numeric;
customersGridView.PagerSettings.Position = PagerPosition.Bottom;
customersGridView.PagerSettings.PageButtonCount = 10;
customersGridView.PagerStyle.BackColor = System.Drawing.Color.LightBlue;
customersGridView.DataKeyNames = new String[] { "CustomerID" };
// Programmatically register the event-handling methods.
customersGridView.PageIndexChanging += new GridViewPageEventHandler(this.CustomersGridView_PageIndexChanging);
customersGridView.RowCancelingEdit += new GridViewCancelEditEventHandler(this.CustomersGridView_RowCancelingEdit);
// Add the GridView control to the Controls collection
// of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView);
}
void CustomersGridView_PageIndexChanging(Object sender, GridViewPageEventArgs e)
{
// User the sender parameter to retrieve the GridView control
// that raised the event.
GridView customersGridView = (GridView)sender;
// Cancel the paging operation if the user attempts to navigate
// to another page while the GridView control is in edit mode.
if (customersGridView.EditIndex != -1)
{
// Use the cancel property to cancel the paging operation.
e.Cancel = true;
// Display an error message.
int newPageNumber = e.NewPageIndex + 1;
Message.Text = "Please update the record before moving to page " +
newPageNumber.ToString() + ".";
}
else
{
// Clear the error message.
Message.Text = "";
}
}
void CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
{
// Clear the error message.
Message.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewPageEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewPageEventHandler 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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
updatecommand="Update Customers SET CompanyName=@CompanyName, Address=@Address, City=@City, PostalCode=@PostalCode, Country=@Country 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 GridView control.
Dim customersGridView As New GridView()
' Set the GridView object's properties.
customersGridView.ID = "CustomersGridView"
customersGridView.DataSourceID = "CustomersSource"
customersGridView.AutoGenerateColumns = True
customersGridView.EmptyDataText = "No data available."
customersGridView.AllowPaging = True
customersGridView.AutoGenerateEditButton = True
customersGridView.PagerSettings.Mode = PagerButtons.Numeric
customersGridView.PagerSettings.Position = PagerPosition.Bottom
customersGridView.PagerSettings.PageButtonCount = 10
customersGridView.PagerStyle.BackColor = System.Drawing.Color.LightBlue
Dim keyArray() As String = {"CustomerID"}
customersGridView.DataKeyNames = keyArray
' Programmatically register the event-handling methods.
AddHandler customersGridView.PageIndexChanging, AddressOf CustomersGridView_PageIndexChanging
AddHandler customersGridView.RowCancelingEdit, AddressOf CustomersGridView_RowCancelingEdit
' Add the GridView control to the Controls collection
' of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView)
End Sub
Sub CustomersGridView_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
' User the sender parameter to retrieve the GridView control
' that raised the event.
Dim customersGridView As GridView = CType(sender, GridView)
' Cancel the paging operation if the user attempts to navigate
' to another page while the GridView control is in edit mode.
If customersGridView.EditIndex <> -1 Then
' Use the cancel property to cancel the paging operation.
e.Cancel = True
' Display an error message.
Dim newPageNumber As Integer = e.NewPageIndex + 1
Message.Text = "Please update the record before moving to page " & _
newPageNumber.ToString() & "."
Else
' Clear the error message.
Message.Text = ""
End If
End Sub
Sub CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
' Clear the error message.
Message.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewPageEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewPageEventHandler 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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
updatecommand="Update Customers SET CompanyName=@CompanyName, Address=@Address, City=@City, PostalCode=@PostalCode, Country=@Country WHERE (CustomerID = @CustomerID)"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Nell'esempio seguente viene illustrato come aggiungere in modo dichiarativo un GridViewPageEventHandler delegato all'evento PageIndexChanging di un GridView 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 CustomersGridView_PageIndexChanging(Object sender, GridViewPageEventArgs e)
{
// Cancel the paging operation if the user attempts to navigate
// to another page while the GridView control is in edit mode.
if (CustomersGridView.EditIndex != -1)
{
// Use the Cancel property to cancel the paging operation.
e.Cancel = true;
// Display an error message.
int newPageNumber = e.NewPageIndex + 1;
Message.Text = "Please update the record before moving to page " +
newPageNumber.ToString() + ".";
}
else
{
// Clear the error message.
Message.Text = "";
}
}
void CustomersGridView_RowCancelingEdit(Object sender, GridViewCancelEditEventArgs e)
{
// Clear the error message.
Message.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridView PageIndexChanging Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView PageIndexChanging Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<br/>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSource"
autogeneratecolumns="true"
emptydatatext="No data available."
allowpaging="true"
autogenerateeditbutton="true"
datakeynames="CustomerID"
onpageindexchanging="CustomersGridView_PageIndexChanging"
onrowcancelingedit="CustomersGridView_RowCancelingEdit"
runat="server">
<pagersettings mode="Numeric"
position="Bottom"
pagebuttoncount="10"/>
<pagerstyle backcolor="LightBlue"/>
</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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
updatecommand="Update Customers SET CompanyName=@CompanyName, Address=@Address, City=@City, PostalCode=@PostalCode, Country=@Country 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 CustomersGridView_PageIndexChanging(ByVal sender As Object, ByVal e As GridViewPageEventArgs)
' Cancel the paging operation if the user attempts to navigate
' to another page while the GridView control is in edit mode.
If CustomersGridView.EditIndex <> -1 Then
' Use the Cancel property to cancel the paging operation.
e.Cancel = True
' Display an error message.
Dim newPageNumber As Integer = e.NewPageIndex + 1
Message.Text = "Please update the record before moving to page " & _
newPageNumber.ToString() & "."
Else
' Clear the error message.
Message.Text = ""
End If
End Sub
Sub CustomersGridView_RowCancelingEdit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
' Clear the error message.
Message.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridView PageIndexChanging Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView PageIndexChanging Example</h3>
<asp:label id="Message"
forecolor="Red"
runat="server"/>
<br/>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSource"
autogeneratecolumns="true"
emptydatatext="No data available."
allowpaging="true"
autogenerateeditbutton="true"
datakeynames="CustomerID"
onpageindexchanging="CustomersGridView_PageIndexChanging"
onrowcancelingedit="CustomersGridView_RowCancelingEdit"
runat="server">
<pagersettings mode="Numeric"
position="Bottom"
pagebuttoncount="10"/>
<pagerstyle backcolor="LightBlue"/>
</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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
updatecommand="Update Customers SET CompanyName=@CompanyName, Address=@Address, City=@City, PostalCode=@PostalCode, Country=@Country WHERE (CustomerID = @CustomerID)"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Commenti
Il GridView controllo genera l'evento PageIndexChanging quando viene selezionato un pulsante cercapersone (un pulsante con la relativa CommandName proprietà impostata su "Page") all'interno del controllo, ma prima che il GridView controllo gestisca l'operazione di paging. In questo modo è possibile fornire un metodo di gestione degli eventi che esegue una routine personalizzata, ad esempio l'annullamento dell'operazione di paging, ogni volta che si verifica questo evento.
Nota
I pulsanti pager si trovano in genere nella riga pager di un GridView controllo .
Quando si crea un delegato GridViewPageEventHandler, 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. |
Si applica a
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