Any more details on how we can get a hold of the mainthread in a Xamarin app?
https://github.com/RolandPheasant/DynamicData.Snippets/blob/master/DynamicData.Snippets/Group/XamarinFormsGrouping.cs#L31

Not been able to create a provider.

i need to pair up my original list like
Observable<A>.Buffer(2).Select(list => Tuple.Create(list[0], list[1]))
but there i have IChangeSet's which converts to Tuple<IChangeSet<A>,IChangeSet<A>> but not to IChangeSet<Tuple<A,A>> so i can't do .Bind(out pairs) on it

Scenario: Tagging Items
2 caches: SourceCache, SourceCache
When item changes, it needs to go thru the list of tags to determine which one applies to it.
Similarly, when tag changes, retagging needs to occur.

First not so reactive attempt:

var disposable = tagsCache.Connect().Flatten().Subscribe(change =>
{
Tag tag = change.Current;

_itemCache.Edit(u => {
    if (change.Reason == ChangeReason.Remove)
    {
        foreach (Item item in _itemCache.Items.Where(b => b.Tags.Contains(tag)))
        {
            item.Tags.Remove(tag);
            u.AddOrUpdate(item);
        }
    }
    else
    {
        foreach (Item item in _itemCache.Items)
        {
            Tag existingTag = item.Tags.FirstOrDefault(t => t.Id == tag.Id);
            if (existingTag != null)
            {
                item.Tags.Remove(existingTag);
                u.AddOrUpdate(item);
            }

            bool applies = tag.Applies(item);
            if (applies)
            {
                item.Tags.Add(tag);
                u.AddOrUpdate(item);
            }
        }
    }
});

});

var disposable2 = _itemCache.Connect().WhereReasonsAre(ChangeReason.Add, ChangeReason.Update).Flatten().Subscribe(change =>
{
Item item = change.Current;

instance.Tags.Connect().Flatten().Select(i => i.Current).Subscribe(tag =>
{
    if (!item.Tags.Contains(tag) && tag.Applies(item))
    {
        item.Tags.Add(tag);
    }
});

});

I am creating an UI Builder for Blazor and in order to update Blazor when changes occur to the backing ViewModel. In particular, I would like to use the property 'Position' changes within the ComponentViewModel base class. The Position property is updated via a separate Drag/Drop service.

I have an interface for ComponentViewModel called IComponentViewModel which is how I've defined my backing DD SourceList.

private SourceList<IComponentViewModel> _componentViewModelSourceList = new SourceList<IComponentViewModel>();
private ReadOnlyObservableCollection<IComponentViewModel>? _childComponents; 

public CompositeDisposable? Disposables { get; set; }
public IObservable<Position> NewPosition { get; }

Within the constructor I am binding the SourceList to a ReadOnlyObservableCollection 'ChildComponents' as follows, which works great!

            Disposables = new CompositeDisposable();

            Disposables.Add(_componentViewModelSourceList
                .Connect() 
                .ObserveOn(RxApp.MainThreadScheduler) 
                .Bind(out _childComponents)
                .DisposeMany()
                .Subscribe());

Also within the constructor I am attempting to AutoRefresh on changes to the 'Position' property within IComponentViewModel as follows...

var NewPosition = _componentViewModelSourceList.Connect()

             // Subscribe to changes on Position property.
             .AutoRefresh(x => x.Position)
             .Select(); 

however I receive the following error.

CS0311: The type '...IComponentViewModel' cannot be used as a type parameter 'TObject' in the generic method 'IObservableListEx.AutoRefresh<TObject, TProperty> ...'

If I change the SourceList to be the ComponentViewModel then the error goes away, however I would prefer (if possible) to keep it as IComponentViewModel.

Is there some way to add an operator to cast the IObservablable ChangeSet so that I can apply the AutoRefresh with the interface approach.

Thank you in advance.

Hi, I'm trying to decouple my VMs from WPF libraries and DynamicData seems to be a great way to do that. I've managed to figure out most of what I was doing before using your snippets and examples, but I've hit something I don't know how to solve.

I had two observable collections, one with all the items and another with the items selected in that collection (bound using an attached behaviour on ListView, which worked fine before). I also have a search text filter for these items, but I want to keep the selected items in the list even if they don't match the search text, so my filter method takes both of those things into account.

I have used .AutoRefreshOnObservable(_ => ...) to listen to changes to the search text using this.WhenValueChanged(...) and the selected items observable using .ToObservable(), which is updating the filter correctly, but is also deselecting all my items when it refreshes.

I found two stackoverflow questions which seemed relevant to my issue:

• Clearing on sort which you already responded to, but isn't the accepted answer (it seems like I want a move rather than remove+insert to keep the item in the selection list)
• Clearing on add which you also responded to, but resetThreshold: int.MaxValue didn't work for me.

I'd really like to be able to continue using this way of presenting my data to the View, but I can't if the collection clearing on changes is unavoidable, so any assistance would be appreciated, thanks.