koStanaEChovek

 var users = context.Users
                .Where(u => u.ProductsSold.Count > 0 && u.ProductsSold.Any(a => a.BuyerId != null))
                .Select(a => new
                {
                    FirstName = a.FirstName,
                    LastName = a.LastName,
                    SoldProducts = a.ProductsSold
                    .Select(b => new
                    {
                        b.Name,
                        Price = b.Price.ToString("F2"),
                        b.Buyer.FirstName,
                        b.Buyer.LastName
                    })
                }).OrderBy(x=> x.LastName).ThenBy(x=> x.FirstName).ToList();
            var resolver = new DefaultContractResolver()
            {
                NamingStrategy = new CamelCaseNamingStrategy()
            };
            var sett = new JsonSerializerSettings();
            sett.ContractResolver = resolver;
            sett.Formatting = Formatting.Indented;

            var json = JsonConvert.SerializeObject(users, sett);
            return json;