XAF之实现子导航栏

点击导航栏某项，出现一个子导航栏，如图：

   实现原理其实很简单，主导航栏的"Navigation System"对应的也是一个DetailView，只不过这个DetailView包含一个Action类型的属性，如果不为该属性设计PropertyEditor，那么该项是无法通过UI编辑的，所以，说白了，就是为Action属性设计一个PropertyEditor。下面讲述一下如何完成这一任务：

1. 首先，定义两个Business类，一个NavigationObject代表图中主显示区的对象，注意包含了一个SingleChoiceAction和子项的集合。

public  class NavigationObject : BaseObject, INotifyPropertyChanged
    {
        private ItemsDisplayStyle defaultChildItemsDisplayStyle = ItemsDisplayStyle.List;
        private NavigationStyle navigationStyle = NavigationStyle.NavBar;
        private SingleChoiceAction action;
        private bool isWebApplication;
        private void action_Execute(object sender, SingleChoiceActionExecuteEventArgs e)
        {
            Console.WriteLine(string.Format("The '{0}' navigation item is selected", e.SelectedChoiceActionItem.Caption));
        }
        private void ProcessItem(NavigationItem item, ChoiceActionItemCollection choiceActionItemCollection, ModelNode parentModel)
        {
            object objectKey = Session.GetKeyValue(item);
            IModelNavigationItem modelNavigaionItem = parentModel.AddNode<IModelNavigationItem>(objectKey.ToString());
            FillNavigationItemModel(item, modelNavigaionItem);
            ChoiceActionItem choiceActionItem = new ChoiceActionItem(modelNavigaionItem, item);
            choiceActionItem.ImageName = item.ImageName;
            choiceActionItemCollection.Add(choiceActionItem);
            SortItems(item.Items);
            foreach (NavigationItem childItem in item.Items)
            {
                ProcessItem(childItem, choiceActionItem.Items, (ModelNode)modelNavigaionItem);
            }
        }
        private void FillNavigationItemModel(NavigationItem item, IModelNavigationItem modelNavigaionItem)
        {
            modelNavigaionItem.Caption = item.Name;
            modelNavigaionItem.Index = item.Index;
            if (item.ChildItemsDisplayStyle == DemoNavigationChildItemsDisplayStyle.Default)
            {
                modelNavigaionItem.ChildItemsDisplayStyle = item.NavigationObject.DefaultChildItemsDisplayStyle;
            }
            else
            {
                modelNavigaionItem.ChildItemsDisplayStyle = item.ChildItemsDisplayStyle == DemoNavigationChildItemsDisplayStyle.List ? ItemsDisplayStyle.List : ItemsDisplayStyle.LargeIcons;
            }
            modelNavigaionItem.ImageName = item.ImageName;
        }
        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        protected override void OnLoaded()
        {
            base.OnLoaded();
            BuildAction();
        }
        internal void BuildAction()
        {
            //B152525
            Action.Items.Clear();
            SortItems(NavigationItems);

            ModelApplicationCreator creator = NavigationDemoWindowController.ModelCreatorInstance;
            if (creator != null)
            {
                ModelNode modelNavigationItems = creator.CreateNode(Guid.NewGuid().ToString(), typeof(IModelNavigationItems));
                foreach (NavigationItem item in NavigationItems)
                {
                    if (item.Parent == null)
                    {
                        ProcessItem(item, Actio