I have an object Concert, which has a collection of Tickets.
Each Ticket has a TicketOption.

I am trying to save the Concert to the database using EF Core. It works if the Ticket collection is null and it worked until I added the TicketOptions to the tickets. Now I am getting errors related to tracking of the TicketOptions.

So previously I had

public override void Save(ConcertEvent concertEvent)
{
    using (var _context = _contextFactory.CreateConcertDataContext())
    {
            _context.Update(concertEvent);
            if (concertEvent.Business != null) { _context.Entry(concertEvent.Business).State = EntityState.Unchanged; }
            if (concertEvent.Venue != null) { _context.Entry(concertEvent.Venue).State = EntityState.Unchanged; }
            
            _context.SaveChanges();
    }
}

When I added TicketOptions this started failing at _context.Update(concertEvent);

To try to fix the issue with TicketOptions I added the following:

public override void Save(ConcertEvent concertEvent)
{
    using (var _context = _contextFactory.CreateConcertDataContext())
    {
            if (concertEvent.Tickets != null)
            {
                var uniqueTicketOptions = concertEvent.Tickets
                                .Where(t => t.TicketOption != null)
                                .Select(t => t.TicketOption);
                                .GroupBy(to => to!.Id)
                                .Select(g => g.First());

                foreach (var t in uniqueTicketOptions)
                {
                    _context.Entry(t!).State = EntityState.Unchanged;
                }
            }
    
            _context.Update(concertEvent);
            if (concertEvent.Business != null) { _context.Entry(concertEvent.Business).State = EntityState.Unchanged; }
            if (concertEvent.Venue != null) { _context.Entry(concertEvent.Venue).State = EntityState.Unchanged; }
            
            _context.SaveChanges();
    }
}

This still fails at _context.Update(concertEvent);

The same applies to Business and Venue, both of which should not be saved/updated and simply setting the EntityState to Unchanged worked perfectly here so I am unsure why it doesn’t work with TicketOptions.

Note – Both Tickets can reference the same or different TicketOptions.