Using BindingOperations.EnableCollectionSynchronization

c# wpf multithreading collections observablecollection
Dilshod picture Dilshod · Feb 12, 2014 · Viewed 23.5k times · Source

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

Drew Noakes picture Drew Noakes · Oct 11, 2016

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

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