1.ProductsInRangeXml

static void GetProductsInRangeXml()
        {
            using (var db = new ProductsShopContext())
            {
                var products = db.Products
                    .Where(p => p.Price >= 1000 && p.Price <= 2000 && p.BuyerId != null)
                    .OrderBy(p => p.Price)
                    .Select(p => new
                    {
                        productName = p.Name,
                        price = p.Price,
                        buyer = $"{p.Buyer.FirstName} {p.Buyer.LastName}"
                    }).ToArray();

                var xDoc = new XDocument();
                xDoc.Add(new XElement("products"));

                //output file - formating: one line (same as sample output)
                foreach (var p in products)
                {
                    xDoc.Root.Add(
                        new XElement("product",
                            new XAttribute("name", $"{p.productName}"),
                            new XAttribute("price", $"{p.price}"),
                            new XAttribute("buyer", $"{p.buyer}")));
                }

                //output file - formating: multiline
                //foreach (var p in products)
                //{
                //    xDoc.Root.Add(
                //        new XElement("product",
                //            new XElement("name", $"{p.productName}"),
                //            new XElement("price", $"{p.price}"),
                //            new XElement("buyer", $"{p.buyer}")));
                //}

                xDoc.Save("OutputFiles/ProductsInRange.xml");
            }
        }