Import Cars

//11. Import Cars
        public static string ImportCars(CarDealerContext context, string inputJson)
        {
            var desCars = JsonConvert.DeserializeObject<CarsInsertDTO[]>(inputJson);

            var validCars = new List<Car>();

            var validPartCars = new List<PartCar>();

            foreach (var car in desCars)
            {
                if (IsValid(car))
                {
                    var newCar = new Car { Make = car.Make, Model = car.Model, TravelledDistance = car.TravelledDistance };
                    validCars.Add(newCar);
                    var partIds = car.PartsID.Distinct().ToList();

                    if (partIds == null)
                        continue;

                    partIds.ForEach(pid =>
                    {
                        var currentPair = new PartCar()
                        {
                            Car = newCar,
                            PartId = pid
                        };
                        newCar.PartCars.Add(currentPair);
                    });
                }
            }
            context.AddRange(validCars);

            context.SaveChanges();

            return $"Successfully imported {validCars.Count}.";
        }

public static bool IsValid(object obj)
        {
            var validationContext = new System.ComponentModel.DataAnnotations.ValidationContext(obj);

            var results = new List<ValidationResult>();

            return Validator.TryValidateObject(obj, validationContext, results, true);
        }


namespace CarDealer.DTO
{
    public class CarsInsertDTO
    {
        public string Make { get; set; }
        public string Model { get; set; }
        public long TravelledDistance { get; set; }
        public int[] PartsID { get; set; }
    }
}