*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.
Download sources and sample aplication.
Introduction
ObservableCollection was introduced in .NET 4 as a native way for binding to WPF
ItemsControls
. 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
and INotifyPropertyChanged
implementation- The same class members, behaviour and interfaces as
List<T>
. Switching from List<T>
to ObservableList<T>
is much easier than to ObservableCollection
- 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 replace
List<..>
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;
int i = 0;
while (employees.Count < i)
{
if (employees[i].IsBadEmployee) employees.RemoveAt(i);
i++;
}
employees.IsCollectionNotificationDisabled = false;
employees.OnCollectionReset();
And 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.