Serializable ObservableCollection alternative
Serializable implementation of ICollectionChanged with the same methods and properties as System.Collections.Generic.List
*EDIT: Do NOT use this!
Although NotifyCollectionChangedEventArgs
supports multiple items in single event call, CollectionViewSource
does not. If AddRange
or RemoveRange
method is used, and CollectionViewSource
will throw an exception. more info: http://blogs.msdn.com/b/nathannesbit/archive/2009/04/20/addrange-and-observablecollection.aspx
I will provide an alternative.
Introduction
ObservableCollection was introduced in .NET 4 as a native way for binding to WPFItemsControls
. It's so cool that we don't have to care about updating UI when collection is changing.
But there is always a 'BUT'. Problems occurs when we try to serialize the collection. The eventhandlers CollectionChanged
and PropertyChanged
are not marked with XmlIgnoreAttribute
and serialization fails it there are any eventhandlers. And also the ObservableCollection
implements lesser (other) interfaces than the old List
. Therefore it can be difficult to simply replace List
with ObservableCollection
in existing code. List
has much more methods which we are used to use.
I wrote the ObservableList
class. It does exactly the same what List
does, but also sends CollectionChanged and PropertyChanged notifications, as ObservableCollection
does. It has the same public
(as well as private
) members as List
.
Features
INotifyCollectionChanged
andINotifyPropertyChanged
implementation- The same class members, behaviour and interfaces as
List<T>
. Switching fromList<T>
toObservableList<T>
is much easier than toObservableCollection
- Better serialization support than
ObservableCollection
- Option to disable notifications. This allow to make multiple changes to the collection without updating UI after every single change
Using the Code
Just replaceList<..>
with ObservableList<..>
in your code and it should work perfectly in most cases.
Sometimes you may want to change the collection rapidly. For example, you go through in loop and make changes. Everytime you change the collection, the CollectionChanged
event is called and if you have binded some ItemsControls
the related items are rebinded. This can have significant performance effect. Therefore I added IsCollectionNotificationDisabled flag. It enables to make changes to collection without the notifications. So the UI will be not updated, until you enables it back.
ObservableCollection employees; ... employees.IsCollectionNotificationDisabled = true; //disable UI updates int i = 0; while (employees.Count < i) { if (employees[i].IsBadEmployee) employees.RemoveAt(i); i++; } employees.IsCollectionNotificationDisabled = false; //enable UI updates employees.OnCollectionReset(); //tells UI to rebindAnd one more thing. Notice that
CollectionChanged
and PropertyChanged
events are marked as NonSerializedAttribute and XmlIgnore. This is not in ObservableCollection
and it may cause serialization problems.