Control.ClearChildState 方法

定義

刪除所有伺服器控制項之子控制項的檢視狀態和控制項狀態資訊。Deletes the view-state and control-state information for all the server control's child controls.

protected:
 void ClearChildState();
protected void ClearChildState ();
member this.ClearChildState : unit -> unit
Protected Sub ClearChildState ()

範例

下列程式碼範例示範如何覆寫樣板化資料繫結控制項的 OnDataBinding 方法。The following code example demonstrates how to override the OnDataBinding method for a templated data-bound control. 如果控制項系結的資料來源已填入,則會使用 Clear 方法清空控制項的 ControlCollection 集合,而 ClearChildState 方法則用來移除已針對子控制項儲存的任何狀態資訊。If the data source that the control binds to is populated, the control's ControlCollection collection is emptied using the Clear method, and the ClearChildState method is used to remove any state information that had been saved for the child controls.

// Override to create the repeated items from the DataSource.
protected override void OnDataBinding(EventArgs e) {
    base.OnDataBinding(e);

    if (DataSource != null) {
        // Clear any existing child controls.
        Controls.Clear();
        // Clear any previous state for the existing child controls.
        ClearChildState();

        // Iterate over the DataSource, creating a new item for each data item.
        IEnumerator dataEnum = DataSource.GetEnumerator();
        int i = 0;
        while(dataEnum.MoveNext()) {

            // Create an item.
            RepeaterItem item = new RepeaterItem(i, dataEnum.Current);
            // Initialize the item from the template.
            ItemTemplate.InstantiateIn(item);
            // Add the item to the ControlCollection.
            Controls.Add(item);

            i++;
        }

        // Prevent child controls from being created again.
        ChildControlsCreated = true;
        // Store the number of items created in view state for postback scenarios.
        ViewState["NumItems"] = i;
    }
}
' Override to create the repeated items from the DataSource.
Protected Overrides Sub OnDataBinding(E As EventArgs)
    MyBase.OnDataBinding(e)

    If Not DataSource Is Nothing
        ' Clear any existing child controls.
        Controls.Clear()
        ' Clear any previous view state for the existing child controls.
        ClearChildState()

        ' Iterate over the DataSource, creating a new item for each data item.
        Dim DataEnum As IEnumerator = DataSource.GetEnumerator()
        Dim I As Integer = 0
        Do While (DataEnum.MoveNext())

            ' Create an item.
            Dim Item As RepeaterItemVB = New RepeaterItemVB(I, DataEnum.Current)
            ' Initialize the item from the template.
            ItemTemplate.InstantiateIn(Item)
            ' Add the item to the ControlCollection.
            Controls.Add(Item)

            I = I + 1
        Loop

        ' Prevent child controls from being created again.
        ChildControlsCreated = true
        ' Store the number of items created in view state for postback scenarios.
        ViewState("NumItems") = I
    End If
End Sub

備註

ClearChildState 方法會清除子控制項的所有檢視狀態和控制狀態資訊。The ClearChildState method clears all view-state and control-state information for child controls. 這相當於呼叫 ClearChildViewState 方法和 ClearChildControlState 方法。It is equivalent to calling both the ClearChildViewState method and the ClearChildControlState method.

重新建立 Control 物件的子控制項時,請使用 ClearChildState 方法來清除子系狀態,使其不會不慎套用至新的控制項。When recreating child controls of a Control object, use the ClearChildState method to clear child state so that it does not get applied to the new controls inadvertently.

適用於

另請參閱