public static PurchaseViewModel ConvertToPurchaseViewModel(Purchase purchase)
        {
            PurchaseViewModel purchaseViewModel = new PurchaseViewModel
            {
                Username = purchase.User.UserName,
                BookTitle = purchase.Book.Title,
                Price = purchase.Price,
                DateOfPurchase = purchase.DateOfPurchase,
                IsRecalled = purchase.IsRecalled
            };

            return purchaseViewModel;
        }