Aggregate of aggregate with EF Core Linq2Sql

Question

I have a ASP.NET Core 2.2 project with EF Core 2.2 Code-First DB. I have the following entities:

• Building, which is basically an address with some other importan

Answer 1

What if you didn't use EF Navigations properties but used manual joins with LINQ to EF?

var ans2 = (from b in dbContext.Buildings
            join f in dbContext.Floors on b.Id equals f.BuildingId into fj
            from f in fj.DefaultIfEmpty()
            join r in dbContext.Rooms on f.Id equals r.FloorId into rj
            from r in rj.DefaultIfEmpty()
            join ro in dbContext.RoomOccupancies on r.Id equals ro.RoomId
            join w in dbContext.WorkGroups on ro.WorkGroupId equals w.Id into wj
            from w in wj.DefaultIfEmpty()
            where !w.IsFinished && w.StartDate < DateTime.Now
            select new BuildingDatableElementDTO() {
                BuildingId = b.Id,
                Name = b.Name,
                FloorCount = fj.Count(),
                RoomCount = rj.Count(),
                CurrentWorkerCount = wj.Sum(w => w.NumberOfEmployees)
           })
           .ToList();