c# - Using BindingOperations.EnableCollectionSynchronization

Question

I have two WPF applications "UI", "Debugger" and one ClassLibrary "BL". UI references to Debugger and BL. Debugger references to BL. I have collection in BL called MyCollection. UI app starts the Debugger app and Debugger binds to a collection MyCollection in BL. When I try changing the MyCollection collection from UI app I am getting exception.

A first chance exception of type 'System.NotSupportedException' occurred in PresentationFramework.dll

Additional information: This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread.

I was googling around and found this: BindingOperations.EnableCollectionSynchronization I can't figure out how to use it. I don't want to reference to any UI dlls from my BL project. Can anybody assist me on that?

Thanks for the help!

Answer 1

All the examples I've seen on Stack Overflow for this get it wrong. You must lock the collection when modifying it from another thread.

On dispatcher (UI) thread:

_itemsLock = new object();
Items = new ObservableCollection<Item>();
BindingOperations.EnableCollectionSynchronization(Items, _itemsLock);

Then from another thread:

lock (_itemsLock)
{
    // Once locked, you can manipulate the collection safely from another thread
    Items.Add(new Item());
    Items.RemoveAt(0);
}

More information in this article: http://10rem.net/blog/2012/01/20/wpf-45-cross-thread-collection-synchronization-redux