Control.ClearChildState 方法

定义

命名空间:

System.Web.UI

程序集:

System.Web.dll

删除服务器控件的所有子控件的视图状态和控件状态信息。

protected:
 void ClearChildState();

protected void ClearChildState ();

member this.ClearChildState : unit -> unit

Protected Sub ClearChildState ()

示例

下面的代码示例演示如何重写 OnDataBinding 模板化数据绑定控件的方法。 如果控件绑定到的数据源已填充，则使用Clear该方法清空控件的ControlCollection集合，并且ClearChildState该方法用于删除为子控件保存的任何状态信息。

// 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

注解

该方法 ClearChildState 清除子控件的所有视图状态和控件状态信息。 它等效于同时调用 ClearChildViewState 方法和 ClearChildControlState 方法。

重新创建对象的子控件 Control 时，请使用该方法 ClearChildState 清除子状态，以便不会无意中应用于新控件。

另请参阅

• ClearChildControlState()
• ClearChildViewState()