Comments on: How to AddRange/RemoveRange in Silverlight ObservableCollection?

By: Royce Tucker

Royce Tucker — Fri, 18 Nov 2011 20:22:30 +0000

The problem here is that you are using NotifyCollectionChangedAction.Reset when you send the collection changed event. This enum value is reserved for when the entire collection needs to be completely reloaded.

The correct logic would set the OldItems and NewItems properties on the NotifyCollectionChangedEventArgs variable and send an event with an Action of NotifyCollectionChangedAction.Add or .Remove.

By: Dew Drop - May 13, 2008 | Alvin Ashcraft's Morning Dew

Dew Drop - May 13, 2008 | Alvin Ashcraft's Morning Dew — Thu, 01 Jan 2009 08:48:03 +0000

Pingback from Dew Drop – May 13, 2008 | Alvin Ashcraft’s Morning Dew

By: Community Blogs

Community Blogs — Thu, 01 Jan 2009 08:48:02 +0000

Joel Neubeck animates user controls, Tim Rule on Scale 9 Images, and Tamir Khason On manipulating ObservableCollection

By: Blogumdan

Blogumdan — Thu, 01 Jan 2009 08:48:00 +0000

İ cant do it.

By: chaiguy1337

chaiguy1337 — Thu, 01 Jan 2009 08:47:58 +0000

When using modal modifiers like deferNotification, it is important to always wrap the reset in a "finally" block, in case an exception happens somewhere above. Otherwise, your class may be left in an inconsistent state:

try {

deferNotification = true;

...

} finally {

deferNotification = false;

}

By: Geert van Horrik

Geert van Horrik — Thu, 01 Jan 2009 08:47:57 +0000

Don't forget to check whether the collection has actually changed in the AddRange or RemoveRange (for example, what if the collection is empty)?

I made some small modifications:

public void AddRange(IEnumerable collection)

{

// Declare variables

bool collectionChanged = false;

// Don't update

_deferNotification = true;

try

{

// Add all items

foreach (T itm in collection)

{

// Add item

Add(itm);

// Collection has changed

collectionChanged = true;

}

finally

{

// Notify again

_deferNotification = false;

}

// Collection has changed

if (collectionChanged)

{

OnCollectionChanged(new System.Collections.Specialized.NotifyCollectionChangedEventArgs(System.Collections.Specialized.NotifyCollectionChangedAction.Reset));

}