public static string ImportParts(CarDealerContext context, string inputJson)
        {
            var parts = JsonConvert.DeserializeObject<List<Part>>(inputJson);

            var suppliersId = context
                .Suppliers
                .Select(s => s.Id)
                .ToList();

            var validParts = new List<Part>();

            foreach (var part in parts)
            {
                if (suppliersId.Contains(part.SupplierId))
                {
                    validParts.Add(part);
                }
            }

            context.Parts.AddRange(validParts);
            context.SaveChanges();

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