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Serializable ObservableCollection alternative

, 13 Jan 2011 CPOL
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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.

 
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 XmlIgnoreAttributeand 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; //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 rebind
 
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.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Liero_

Slovakia Slovakia
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Comments and Discussions

 
GeneralReason for my vote of 1 Lots of errors. For instance, in .NE... PinmemberSledgeHammer0110-Jan-11 10:45 
GeneralReason for my vote of 3 -Poor writing. Many spelling errors.... PinmemberJulien Bouvier24-Oct-10 5:38 

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