使用 lambda 进行 ObservableCollection 切片
我有 ObservableCollectionViewUnit 实现 INotifyPropertyChanged。
ViewUnit 具有 Handled : bool 属性。
WPF 应用程序的主视图有一个绑定到 _myItems 的 ListBox。
我只想要未处理的项目的单独视图，即拥有一个依赖于现有 _myItems 的 IObservableCollection<> 但仅包含已过滤的项目，最好使用拉姆达表达式。
理想情况下，
IObservableCollection<ViewUnit> _myFilteredCollection = HelperClass<ViewUnit>.FromExisting(_myItems, (e) => !e.Handled);
我可以自己实现它。我只是觉得有人解决了这个问题并且有一个很好的解决方案（我只是不知道它的名字）。
I have ObservableCollection<ViewUnit> _myItems field, where ViewUnit implements INotifyPropertyChanged.
ViewUnit has Handled : bool property.
The main view of WPF application has a ListBox which binds to _myItems.
I want a separate view of non-handled items only, that is, to have an IObservableCollection<> depended on existing _myItems but having only filtered items, preferably, using a lambda expression.
Ideally, this would be
IObservableCollection<ViewUnit> _myFilteredCollection = HelperClass<ViewUnit>.FromExisting(_myItems, (e) => !e.Handled);
I could implement it on my own. I just feel somebody though this problem through and has a good solution available (I just don't know its name).
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查看 CollectionView。这是围绕处理过滤、分组和排序的集合的视图。当您要求 WPF 绑定到集合时，它实际上绑定到其默认视图，因此您可以像这样过滤默认集合视图：
过滤器是
object上的谓词，因此您必须将参数强制转换为ViewUnit。如果属性发生变化，它也不会收到通知，因此如果Handled属性发生变化，您需要调用collectionView.Refresh。不过，如果您在_myItems中添加或删除，它将会更新。另请查看 Bea Stollnitz 的博客文章如何从集合中过滤项目。
Take a look at CollectionView. This is a view around a collection that handles filtering, grouping, and sorting. When you ask WPF to bind to a collection it actually binds to its default view, so you can just filter the default collection view like this:
The filter is a predicate on
object, so you'll have to cast the parameter toViewUnit. It also won't be notified if the property changes, so you'll need to callcollectionView.Refreshif theHandledproperty changes. It will be updated if you add or remove from_myItems, though.Also check out Bea Stollnitz's blog entry How do I filter items from a collection.