DataControlField.OnFieldChanged 方法

定義

引發 FieldChanged 事件。Raises the FieldChanged event.

protected:
 virtual void OnFieldChanged();
protected virtual void OnFieldChanged ();
abstract member OnFieldChanged : unit -> unit
override this.OnFieldChanged : unit -> unit
Protected Overridable Sub OnFieldChanged ()

備註

OnFieldChanged方法會引發事件,通知物件的 DataControlField 狀態已變更。The OnFieldChanged method raises an event signaling that the DataControlField object's state has changed. 變更下列屬性會導致引發此事件: FooterTextHeaderImageUrlHeaderTextShowHeaderSortExpressionVisibleChanges to the following properties cause this event to be raised: FooterText, HeaderImageUrl, HeaderText, ShowHeader, SortExpression, and Visible. 當狀態變更發生時,衍生型別屬性也會引發此事件。Derived type properties also raise this event when state changes occur. Web 服務器控制項(例如 DetailsViewGridView 通常會呼叫 DataBind 方法來回應欄位變更事件。Web server controls such as DetailsView and GridView typically call the DataBind method in response to a field change event.

引發事件會透過委派叫用此事件處理常式。Raising an event invokes the event handler through a delegate. 如需詳細資訊,請參閱 處理和引發事件For more information, see Handling and Raising Events.

OnFieldChanged 方法也允許衍生類別處理事件,而不用附加委派。The OnFieldChanged method also allows derived classes to handle the event without attaching a delegate. 這是在衍生類別中處理事件的慣用技巧。This is the preferred technique for handling the event in a derived class.

給繼承者的注意事項

當在衍生類別中覆寫 OnFieldChanged() 時,請確定呼叫基底類別的 OnFieldChanged() 方法,使已註冊的委派能接收到事件。When overriding OnFieldChanged() in a derived class, be sure to call the base class's OnFieldChanged() method so that registered delegates receive the event.

適用於