StateBag.IsItemDirty(String) 方法

定义

命名空间:

System.Web.UI

程序集:

System.Web.dll

检查 StateItem 对象中存储的 StateBag 对象，以计算自调用 TrackViewState() 后该对象是否进行了修改。

public:
 bool IsItemDirty(System::String ^ key);

public bool IsItemDirty (string key);

member this.IsItemDirty : string -> bool

Public Function IsItemDirty (key As String) As Boolean

参数

key

String

要检查的项的键。

返回

Boolean

如果项已修改，则为 true；否则为 false。

示例

下面的代码示例演示如何使用 IsItemDirty 方法。

// 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

注解

如果 对象中StateBag不存在参数，key此方法也会返回 false 。

另请参阅

• ViewState