GridViewUpdatedEventArgs.OldValues Propriété
Définition
Important
Certaines informations portent sur la préversion du produit qui est susceptible d’être en grande partie modifiée avant sa publication. Microsoft exclut toute garantie, expresse ou implicite, concernant les informations fournies ici.
Obtient un dictionnaire qui contient les paires nom-valeur de champ d'origine pour l'enregistrement mis à jour.
public:
property System::Collections::Specialized::IOrderedDictionary ^ OldValues { System::Collections::Specialized::IOrderedDictionary ^ get(); };public System.Collections.Specialized.IOrderedDictionary OldValues { get; }member this.OldValues : System.Collections.Specialized.IOrderedDictionaryPublic ReadOnly Property OldValues As IOrderedDictionaryValeur de propriété
Dictionnaire des paires nom-valeur de champ d'origine pour l'enregistrement mis à jour.
Exemples
L’exemple suivant montre comment accéder aux valeurs d’origine des champs non clés pour l’enregistrement mis à jour.
<%@ 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_RowUpdated(Object sender, GridViewUpdatedEventArgs e)
{
// Use the Exception property to determine whether an exception
// occurred during the update operation.
if (e.Exception == null)
{
// Sometimes an error might occur that does not raise an
// exception, but prevents the update operation from
// completing. Use the AffectedRows property to determine
// whether the record was actually updated.
if (e.AffectedRows == 1)
{
// Use the Keys property to get the value of the key field.
String keyFieldValue = e.Keys["CustomerID"].ToString();
// Display a confirmation message.
Message.Text = "Record " + keyFieldValue +
" updated successfully. ";
// Display the new and original values.
DisplayValues((OrderedDictionary)e.NewValues, (OrderedDictionary)e.OldValues);
}
else
{
// Display an error message.
Message.Text = "An error occurred during the update operation.";
// When an error occurs, keep the GridView
// control in edit mode.
e.KeepInEditMode = true;
}
}
else
{
// Insert the code to handle the exception.
Message.Text = e.Exception.Message;
// Use the ExceptionHandled property to indicate that the
// exception is already handled.
e.ExceptionHandled = true;
e.KeepInEditMode = true;
}
}
void DisplayValues(OrderedDictionary newValues, OrderedDictionary oldValues)
{
Message.Text += "<br/></br>";
// Iterate through the new and old values. Display the
// values on the page.
for (int i = 0; i < oldValues.Count; i++)
{
Message.Text += "Old Value=" + oldValues[i].ToString() +
", New Value=" + newValues[i].ToString() + "<br/>";
}
Message.Text += "</br>";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewUpdatedEventArgs Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewUpdatedEventArgs Example</h3>
<!-- The GridView control automatically sets the columns -->
<!-- specified in the datakeynames property as read-only. -->
<!-- No input controls are rendered for these columns in -->
<!-- edit mode. -->
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSqlDataSource"
autogeneratecolumns="true"
autogenerateeditbutton="true"
allowpaging="true"
datakeynames="CustomerID"
onrowupdated="CustomersGridView_RowUpdated"
runat="server">
</asp:gridview>
<br/>
<asp:label id="Message"
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="CustomersSqlDataSource"
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">
</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 CustomersGridView_RowUpdated(sender As Object, e As GridViewUpdatedEventArgs)
' Use the Exception property to determine whether an exception
' occurred during the update operation.
If e.Exception Is Nothing Then
' Sometimes an error might occur that does not raise an
' exception, but prevents the update operation from
' completing. Use the AffectedRows property to determine
' whether the record was actually updated.
If e.AffectedRows = 1 Then
' Use the Keys property to get the value of the key field.
Dim keyFieldValue As String = e.Keys("CustomerID").ToString()
' Display a confirmation message.
Message.Text = "Record " & keyFieldValue & _
" updated successfully. "
' Display the new and original values.
DisplayValues(CType(e.NewValues, OrderedDictionary), CType(e.OldValues, OrderedDictionary))
Else
' Display an error message.
Message.Text = "An error occurred during the update operation."
' When an error occurs, keep the GridView
' control in edit mode.
e.KeepInEditMode = True
End If
Else
' Insert the code to handle the exception.
Message.Text = e.Exception.Message
' Use the ExceptionHandled property to indicate that the
' exception is already handled.
e.ExceptionHandled = True
e.KeepInEditMode = True
End If
End Sub
Sub DisplayValues(ByVal newValues As OrderedDictionary, ByVal oldValues As OrderedDictionary)
Message.Text &= "<br/></br>"
' Iterate through the new and old values. Display the
' values on the page.
Dim i As Integer
For i = 0 To oldValues.Count - 1
Message.Text &= "Old Value=" & oldValues(i).ToString() & _
", New Value=" & newValues(i).ToString() & "<br/>"
Next
Message.Text &= "</br>"
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewUpdatedEventArgs Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewUpdatedEventArgs Example</h3>
<!-- The GridView control automatically sets the columns -->
<!-- specified in the datakeynames property as read-only. -->
<!-- No input controls are rendered for these columns in -->
<!-- edit mode. -->
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSqlDataSource"
autogeneratecolumns="true"
autogenerateeditbutton="true"
allowpaging="true"
datakeynames="CustomerID"
onrowupdated="CustomersGridView_RowUpdated"
runat="server">
</asp:gridview>
<br/>
<asp:label id="Message"
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="CustomersSqlDataSource"
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">
</asp:sqldatasource>
</form>
</body>
</html>
Remarques
Utilisez la OldValues propriété pour accéder aux valeurs de champ d’origine de l’enregistrement mis à jour. Par exemple, vous pouvez utiliser ces valeurs pour conserver un journal des enregistrements mis à jour.
La propriété OldValues retourne un objet qui implémente l'interface System.Collections.Specialized.IOrderedDictionary. L’objet contient des System.Collections.DictionaryEntry objets qui représentent les champs de l’enregistrement mis à jour avec leurs valeurs d’origine.
Notes
Comme raccourci, vous pouvez également utiliser l’indexeur de l’objet IOrderedDictionary pour accéder directement aux valeurs de champ.
S’applique à
Voir aussi
Collaborer avec nous sur GitHub
La source de ce contenu se trouve sur GitHub, où vous pouvez également créer et examiner les problèmes et les demandes de tirage. Pour plus d’informations, consultez notre guide du contributeur.
