StateBag.IsItemDirty(String) 方法

定義

檢查儲存於 StateItem 物件的 StateBag 物件,以評估自從呼叫 TrackViewState() 以來,它是否已經被修改。Checks a StateItem object stored in the StateBag object to evaluate whether it has been modified since the call to TrackViewState().

public:
 bool IsItemDirty(System::String ^ key);
public bool IsItemDirty (string key);
member this.IsItemDirty : string -> bool
Public Function IsItemDirty (key As String) As Boolean

參數

key
String

要檢查的項目索引鍵。The key of the item to check.

傳回

如果項目已經被修改則為 true,否則為 falsetrue if the item has been modified; otherwise, false.

範例

下列程式碼範例將示範如何使用 IsItemDirty 方法。The following code example demonstrates using the IsItemDirty method.

// 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.
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


備註

如果 key 參數不存在於 StateBag 物件中,這個方法也會傳回 falseThis method also returns false if the key parameter does not exist in the StateBag object.

適用於

另請參閱