FormViewDeletedEventArgs.Keys Proprietà
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Ottiene un dizionario ordinato delle coppie nome/valore dei campi chiave del record eliminato.
public:
property System::Collections::Specialized::IOrderedDictionary ^ Keys { System::Collections::Specialized::IOrderedDictionary ^ get(); };public System.Collections.Specialized.IOrderedDictionary Keys { get; }member this.Keys : System.Collections.Specialized.IOrderedDictionaryPublic ReadOnly Property Keys As IOrderedDictionaryValore della proprietà
Un oggetto OrderedDictionary contenente le coppie nome/valore dei campi chiave del record eliminato.
Esempio
Nell'esempio seguente viene illustrato come usare la Keys proprietà per accedere ai valori dei campi chiave per un record eliminato.
<%@ 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 EmployeeFormView_ItemDeleted(Object sender, FormViewDeletedEventArgs e)
{
// Display the values of the key fields in the Keys property.
KeysMessageLabel.Text =
"The key fields for the deleted record are: <br/>";
foreach (DictionaryEntry entry in e.Keys)
{
DisplayValue(entry, KeysMessageLabel);
}
// Display the values of the non-key fields in the Values
// property.
ValuesMessageLabel.Text =
"The non-key fields for the deleted record are: <br/>";
foreach (DictionaryEntry entry in e.Values)
{
DisplayValue(entry, ValuesMessageLabel);
}
}
void DisplayValue(DictionaryEntry entry, Label displayLabel)
{
// Display the field name contained in the DictionaryEntry object.
if (entry.Key != null)
{
displayLabel.Text += "Name=" + entry.Key.ToString() + ", ";
}
else
{
displayLabel.Text += "Name=null, ";
}
// Display the field value contained in the DictionaryEntry object.
if (entry.Value != null)
{
displayLabel.Text += "Value=" + entry.Value.ToString() + "<br/>";
}
else
{
displayLabel.Text += "Value=null<br/>";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewDeletedEventArgs Keys and Values Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewDeletedEventArgs Keys and Values Example</h3>
<asp:formview id="EmployeeFormView"
datasourceid="EmployeeSource"
allowpaging="true"
datakeynames="EmployeeID"
onitemdeleted="EmployeeFormView_ItemDeleted"
runat="server">
<itemtemplate>
<table>
<tr>
<td>
<asp:image id="EmployeeImage"
imageurl='<%# Eval("PhotoPath") %>'
alternatetext='<%# Eval("LastName") %>'
runat="server"/>
</td>
<td>
<asp:label id="FirstNameLabel"
text='<%#Bind("FirstName")%>'
font-bold="true"
runat="server"/>
<asp:label id="LastNameLabel"
text='<%#Bind("LastName")%>'
font-bold="true"
runat="server"/>
<br/>
<asp:label id="TitleLabel"
text='<%#Bind("Title")%>'
runat="server"/>
</td>
</tr>
<tr>
<td colspan="2">
<asp:button id="DeleteButton"
text="Delete Record"
commandname="Delete"
runat="server" />
</td>
</tr>
</table>
</itemtemplate>
</asp:formview>
<asp:label id="KeysMessageLabel"
forecolor="Red"
runat="server"/>
<br/><br/>
<asp:label id="ValuesMessageLabel"
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], [Title], [PhotoPath] From [Employees]"
deletecommand="Delete [Employees] Where [EmployeeID]=@EmployeeID"
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 EmployeeFormView_ItemDeleted(ByVal sender As Object, ByVal e As FormViewDeletedEventArgs) Handles EmployeeFormView.ItemDeleted
Dim entry As DictionaryEntry
' Display the values of the key fields in the Keys property.
KeysMessageLabel.Text = _
"The key fields for the deleted record are: <br/>"
' In Visual Basic, you cannot iterate through the DictionaryEntry objects
' in the Keys property directly. Use the CopyTo method to
' copy the objects to an array first.
Dim keysArray(e.Keys.Count - 1) As DictionaryEntry
e.Keys.CopyTo(keysArray, 0)
' Iterate through the array and display its values.
For Each entry In keysArray
DisplayValue(entry, KeysMessageLabel)
Next
' Display the values of the non-key fields in the Values
' property.
ValuesMessageLabel.Text = _
"The non-key fields for the deleted record are: <br/>"
Dim valuesArray(e.Values.Count - 1) As DictionaryEntry
e.Values.CopyTo(valuesArray, 0)
For Each entry In valuesArray
DisplayValue(entry, ValuesMessageLabel)
Next
End Sub
Sub DisplayValue(ByVal entry As DictionaryEntry, ByVal displayLabel As Label)
' Display the field name contained in the DictionaryEntry object.
If entry.Key IsNot Nothing Then
displayLabel.Text &= "Name=" & entry.Key.ToString() & ", "
Else
displayLabel.Text &= "Name=null, "
End If
' Display the field value contained in the DictionaryEntry object.
If entry.Value IsNot Nothing Then
displayLabel.Text &= "Value=" & entry.Value.ToString() & "<br/>"
Else
displayLabel.Text &= "Value=null<br/>"
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewDeletedEventArgs Keys and Values Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewDeletedEventArgs Keys and Values Example</h3>
<asp:formview id="EmployeeFormView"
datasourceid="EmployeeSource"
allowpaging="true"
datakeynames="EmployeeID"
runat="server">
<itemtemplate>
<table>
<tr>
<td>
<asp:image id="EmployeeImage"
imageurl='<%# Eval("PhotoPath") %>'
alternatetext='<%# Eval("LastName") %>'
runat="server"/>
</td>
<td>
<asp:label id="FirstNameLabel"
text='<%#Bind("FirstName")%>'
font-bold="true"
runat="server"/>
<asp:label id="LastNameLabel"
text='<%#Bind("LastName")%>'
font-bold="true"
runat="server"/>
<br/>
<asp:label id="TitleLabel"
text='<%#Bind("Title")%>'
runat="server"/>
</td>
</tr>
<tr>
<td colspan="2">
<asp:button id="DeleteButton"
text="Delete Record"
commandname="Delete"
runat="server" />
</td>
</tr>
</table>
</itemtemplate>
</asp:formview>
<asp:label id="KeysMessageLabel"
forecolor="Red"
runat="server"/>
<br/><br/>
<asp:label id="ValuesMessageLabel"
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], [Title], [PhotoPath] From [Employees]"
deletecommand="Delete [Employees] Where [EmployeeID]=@EmployeeID"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Commenti
La Keys proprietà contiene i valori dei campi chiave elencati nella DataKeyNames proprietà di un FormView controllo. Utilizzare la Keys proprietà per accedere ai valori dei campi chiave (come specificato dalla DataKeyNames proprietà) per un record eliminato. Ad esempio, è possibile usare questi valori per mantenere un log di record eliminati.
Nota
Questa proprietà contiene solo i campi chiave specificati nella DataKeyNames proprietà. Per accedere ai campi non chiave, usare la Values proprietà .
La Keys proprietà restituisce un OrderedDictionary oggetto che implementa l'interfaccia System.Collections.Specialized.IOrderedDictionary . L'oggetto OrderedDictionary contiene System.Collections.DictionaryEntry oggetti che rappresentano i campi chiave del record eliminato. Per accedere ai nomi dei campi, usare la Keys proprietà dell'oggetto OrderedDictionary . Analogamente, è possibile accedere ai valori dei campi usando la Values proprietà .
Nota
Come collegamento, è anche possibile usare l'indicizzatore dell'oggetto OrderedDictionary per accedere ai valori del campo chiave. Il vantaggio nell'uso dell'indicizzatore è che restituisce direttamente i valori del campo chiave. I controlli origine dati che si basano sull'ordine di campo (ad esempio AccessDataSource) possono accedere ai valori dei campi chiave solo per indice.