StateBag.IsItemDirty-Methode

Überprüft ein im StateBag-Objekt gespeichertes StateItem-Objekt, um auszuwerten, ob es seit dem Aufruf von Control.TrackViewState geändert wurde.

Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)

Syntax

'Declaration
Public Function IsItemDirty ( _
    key As String _
) As Boolean
'Usage
Dim instance As StateBag
Dim key As String
Dim returnValue As Boolean

returnValue = instance.IsItemDirty(key)

public bool IsItemDirty (
    string key
)

public:
bool IsItemDirty (
    String^ key
)

public boolean IsItemDirty (
    String key
)

public function IsItemDirty (
    key : String
) : boolean

Parameter

• key
  Der Schlüssel des zu überprüfenden Elements.

Rückgabewert

true, wenn das Element geändert wurde, andernfalls false.

Hinweise

Diese Methode gibt auch false zurück, wenn der key-Parameter nicht im StateBag-Objekt vorhanden ist.

Beispiel

Im folgenden Codebeispiel wird die Verwendung der IsItemDirty-Methode veranschaulicht.

' Implement the SaveViewState method. If the StateBag
' that stores the MyItem class's view state contains
' a value for the message property and if the value
' has changed since the TrackViewState method was last 
' called, all view state for this class is deleted, 
' using the StateBag.Clear method,and the new value is added.
Function SaveViewState() As Object Implements IStateManager.SaveViewState
    ' Check whether the message property exists in 
    ' the ViewState property, and if it does, check
    ' whether it has changed since the most recent
    ' TrackViewState method call.
    If Not CType(_viewstate, IDictionary).Contains("message") OrElse _viewstate.IsItemDirty("message") Then
        _viewstate.Clear()
        ' Add the _message property to the StateBag.
        _viewstate.Add("message", _message)
    End If
    Return CType(_viewstate, IStateManager).SaveViewState()
End Function 'IStateManager.SaveViewState

// Implement the SaveViewState method. If the StateBag
// that stores the MyItem class's view state contains
// a value for the message property and if the value
// has changed since the TrackViewState method was last 
// called, all view state for this class is deleted, 
// using the StateBag.Clear method,and the new value is added.
object IStateManager.SaveViewState()
{
    // Check whether the message property exists in 
    // the ViewState property, and if it does, check
    // whether it has changed since the most recent
    // TrackViewState method call.
    if (!((IDictionary)_viewstate).Contains("message") || _viewstate.IsItemDirty("message"))
    {
        _viewstate.Clear();
        // Add the _message property to the StateBag.
        _viewstate.Add("message", _message);
    }
    return ((IStateManager)_viewstate).SaveViewState();
}

// Implement the SaveViewState method. If the StateBag
// that stores the MyItem class's view state contains
// a value for the message property and if the value
// has changed since the TrackViewState method was last 
// called, all view state for this class is deleted, 
// using the StateBag.Clear method,and the new value is added.
public Object SaveViewState()
{
    // Check whether the message property exists in 
    // the ViewState property, and if it does, check
    // whether it has changed since the most recent
    // TrackViewState method call.
    if (!(((IDictionary)_viewState).Contains("message")) 
        || _viewState.IsItemDirty("message")) {
        {
            _viewState.Clear();
            // Add the _message property to the StateBag.
            _viewState.Add("message", _message);
        }
    }
    return ((IStateManager)_viewState).SaveViewState();
} //SaveViewState

Plattformen

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

StateBag-Klasse
StateBag-Member
System.Web.UI-Namespace
Control.ViewState-Eigenschaft