public ModelToModel GetAll()
        {
            ModelToModel mm;

            mm = new ModelToModel();
            mm.bookVariableInfoes = new List<BookVariableInfo>();
            using (BookMarketDbContext db = new BookMarketDbContext())
            {
                foreach (var entry in db.GetAllBookVariableInfoes())
                    mm.bookVariableInfoes.Add(entry);
            }
            return mm;
        }