C＃的ObservableCollection OnCollectionChanged不费一枪项目更改时 [英] C# ObservableCollection OnCollectionChanged not firing when item changes
问题描述
从MSDN约OnCollectionChanged：当一个项目被添加，删除，更改后发生，移动或整个列表刷新
From the MSDN about OnCollectionChanged: "Occurs when an item is added, removed, changed, moved, or the entire list is refreshed."
我改变一个属性附加到驻留在我的收藏的OBJ，但OnCollectionChanged不会被解雇。我在obj的类实现INotifyPropertyChanged的。
I'm changing a property attached to an obj that resides in my collection, but OnCollectionChanged isn't fired. I am implementing iNotifyPropertyChanged on the obj class.
public class ObservableBatchCollection : ObservableCollection<BatchData>
{
protected override void OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
if(e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
{
foreach (BatchData item in e.NewItems)
{
}
}
base.OnCollectionChanged(e);
}
public ObservableBatchCollection(IEnumerable<BatchData> items)
: base(items)
{
}
}
对于我来说，读取时集合中的一个项目更改，如的属性对象，此事件应激发。这不，但是。我希望能够在需要时，知道什么时候在我的定义集合改变的项目，所以我可以在其上进行计算。
To me, that reads that when an item in the collection is changed, such as a property of the object, that this event should fire. It's not, however. I want to be able to know when an item in my custom collection changes so I can perform a calculation on it, if needed.
有什么想法？
推荐答案
的ObservableCollection< ; T> 引发事件，只有当集合本身更改的。包含有突变其内部状态的集合中的项目还没有改变集合的结构和的ObservableCollection< T> 将不会报告它
ObservableCollection<T> raises events only when the collection itself changes. An item contained in the collection that has its internal state mutated has not altered the structure of the collection, and ObservableCollection<T> will not report it.
一种选择是继承的ObservableCollection< T> 和订阅每个项目的 OnPropertyChanged 当它被添加的事件。在该处理程序中，你可以提高或者是自定义事件，或退回到收藏自己的PropertyChanged 事件。请注意，如果你走这条路，你应该增加一个通用的限制，使 T：INotifyPropertyChanged的
One option is to subclass ObservableCollection<T> and subscribe to each item's OnPropertyChanged event when it is added. In that handler, you can raise either a custom event, or fall back to the collection's own PropertyChanged event. Note that if you do go this route, you should add a generic constraint so that T : INotifyPropertyChanged.
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