Prevent negative item orders (#392)

* Pulling changes over from previous branch

* Adding exception and guard clause

src/ApplicationCore/Entities/BasketAggregate/BasketItem.cs

@@ -1,4 +1,7 @@
-namespace Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate
+using Ardalis.GuardClauses;
+using System;
+
+namespace Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate
 {
     public class BasketItem : BaseEntity
     {
@@ -11,17 +14,21 @@
         public BasketItem(int catalogItemId, int quantity, decimal unitPrice)
         {
             CatalogItemId = catalogItemId;
-            Quantity = quantity;
             UnitPrice = unitPrice;
+            SetQuantity(quantity);
         }
 
         public void AddQuantity(int quantity)
         {
+            Guard.Against.OutOfRange(quantity, nameof(quantity), 0, int.MaxValue);
+
             Quantity += quantity;
         }
 
-        public void SetNewQuantity(int quantity)
+        public void SetQuantity(int quantity)
         {
+            Guard.Against.OutOfRange(quantity, nameof(quantity), 0, int.MaxValue);
+
             Quantity = quantity;
         }
     }

src/ApplicationCore/Exceptions/EmptyBasketOnCheckoutException.cs

@@ -0,0 +1,24 @@
+using System;
+
+namespace Microsoft.eShopWeb.ApplicationCore.Exceptions
+{
+    public class EmptyBasketOnCheckoutException : Exception
+    {
+        public EmptyBasketOnCheckoutException()
+            : base($"Basket cannot have 0 items on checkout")
+        {
+        }
+
+        protected EmptyBasketOnCheckoutException(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context) : base(info, context)
+        {
+        }
+
+        public EmptyBasketOnCheckoutException(string message) : base(message)
+        {
+        }
+
+        public EmptyBasketOnCheckoutException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+    }
+}

src/ApplicationCore/Exceptions/GuardExtensions.cs

@@ -1,5 +1,7 @@
 using Microsoft.eShopWeb.ApplicationCore.Exceptions;
 using Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace Ardalis.GuardClauses
 {
@@ -10,5 +12,11 @@ namespace Ardalis.GuardClauses
             if (basket == null)
                 throw new BasketNotFoundException(basketId);
         }
+
+        public static void EmptyBasketOnCheckout(this IGuardClause guardClause, IReadOnlyCollection<BasketItem> basketItems)
+        {
+            if (!basketItems.Any())
+                throw new EmptyBasketOnCheckoutException();
+        }
     }
 }

src/ApplicationCore/Services/BasketService.cs

@@ -55,12 +55,13 @@ namespace Microsoft.eShopWeb.ApplicationCore.Services
             Guard.Against.Null(quantities, nameof(quantities));
             var basket = await _basketRepository.GetByIdAsync(basketId);
             Guard.Against.NullBasket(basketId, basket);
+
             foreach (var item in basket.Items)
             {
                 if (quantities.TryGetValue(item.Id.ToString(), out var quantity))
                 {
                     if (_logger != null) _logger.LogInformation($"Updating quantity of item ID:{item.Id} to {quantity}.");
-                    item.SetNewQuantity(quantity);
+                    item.SetQuantity(quantity);
                 }
             }
             basket.RemoveEmptyItems();

src/ApplicationCore/Services/OrderService.cs

@@ -33,6 +33,7 @@ namespace Microsoft.eShopWeb.ApplicationCore.Services
             var basket = await _basketRepository.FirstOrDefaultAsync(basketSpec);
 
             Guard.Against.NullBasket(basketId, basket);
+            Guard.Against.EmptyBasketOnCheckout(basket.Items);
 
             var catalogItemsSpecification = new CatalogItemsSpecification(basket.Items.Select(item => item.CatalogItemId).ToArray());
             var catalogItems = await _itemRepository.ListAsync(catalogItemsSpecification);

src/Web/Pages/Basket/BasketItemViewModel.cs

@@ -1,4 +1,6 @@
-namespace Microsoft.eShopWeb.Web.Pages.Basket
+using System.ComponentModel.DataAnnotations;
+
+namespace Microsoft.eShopWeb.Web.Pages.Basket
 {
     public class BasketItemViewModel
     {
@@ -7,7 +9,10 @@
         public string ProductName { get; set; }
         public decimal UnitPrice { get; set; }
         public decimal OldUnitPrice { get; set; }
+
+        [Range(0, int.MaxValue, ErrorMessage = "Quantity must be bigger than 0")]
         public int Quantity { get; set; }
+        
         public string PictureUrl { get; set; }
     }
 }

src/Web/Pages/Basket/Checkout.cshtml.cs

@@ -3,11 +3,13 @@ using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.RazorPages;
 using Microsoft.eShopWeb.ApplicationCore.Entities.OrderAggregate;
+using Microsoft.eShopWeb.ApplicationCore.Exceptions;
 using Microsoft.eShopWeb.ApplicationCore.Interfaces;
 using Microsoft.eShopWeb.Infrastructure.Identity;
 using Microsoft.eShopWeb.Web.Interfaces;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 
 namespace Microsoft.eShopWeb.Web.Pages.Basket
@@ -19,16 +21,19 @@ namespace Microsoft.eShopWeb.Web.Pages.Basket
         private readonly IOrderService _orderService;
         private string _username = null;
         private readonly IBasketViewModelService _basketViewModelService;
+        private readonly IAppLogger<CheckoutModel> _logger;
 
         public CheckoutModel(IBasketService basketService,
             IBasketViewModelService basketViewModelService,
             SignInManager<ApplicationUser> signInManager,
-            IOrderService orderService)
+            IOrderService orderService,
+            IAppLogger<CheckoutModel> logger)
         {
             _basketService = basketService;
             _signInManager = signInManager;
             _orderService = orderService;
             _basketViewModelService = basketViewModelService;
+            _logger = logger;
         }
 
         public BasketViewModel BasketModel { get; set; } = new BasketViewModel();
@@ -44,15 +49,28 @@ namespace Microsoft.eShopWeb.Web.Pages.Basket
             }
         }
 
-        public async Task<IActionResult> OnPost(Dictionary<string, int> items)
+        public async Task<IActionResult> OnPost(IEnumerable<BasketItemViewModel> items)
+        {
+            try
             {
                 await SetBasketModelAsync();
 
-            await _basketService.SetQuantities(BasketModel.Id, items);
+                if (!ModelState.IsValid)
+                {
+                    return BadRequest();
+                }
 
+                var updateModel = items.ToDictionary(b => b.Id.ToString(), b => b.Quantity);
+                await _basketService.SetQuantities(BasketModel.Id, updateModel);
                 await _orderService.CreateOrderAsync(BasketModel.Id, new Address("123 Main St.", "Kent", "OH", "United States", "44240"));
-
                 await _basketService.DeleteBasketAsync(BasketModel.Id);               
+            }
+            catch (EmptyBasketOnCheckoutException emptyBasketOnCheckoutException)
+            {
+                //Redirect to Empty Basket page
+                _logger.LogWarning(emptyBasketOnCheckoutException.Message);
+                return RedirectToPage("/Basket/Index");
+            }
 
             return RedirectToPage();
         }

src/Web/Pages/Basket/Index.cshtml

@@ -23,6 +23,7 @@
                 <section class="esh-basket-title col-xs-2">Cost</section>
             </article>
             <div class="esh-catalog-items row">
+                <div asp-validation-summary="All" class="text-danger"></div>
                 @for (int i = 0; i < Model.BasketModel.Items.Count; i++)
                 {
                     var item = Model.BasketModel.Items[i];
@@ -34,20 +35,17 @@
                     <section class="esh-basket-item esh-basket-item--middle col-xs-3">@item.ProductName</section>
                     <section class="esh-basket-item esh-basket-item--middle col-xs-2">$ @item.UnitPrice.ToString("N2")</section>
                     <section class="esh-basket-item esh-basket-item--middle col-xs-2">
-                                <input type="hidden" name="@("Items[" + i + "].Key")" value="@item.Id" />
-                                <input type="number" class="esh-basket-input" min="0" name="@("Items[" + i + "].Value")" value="@item.Quantity" />
+                        <input type="hidden" name="@("Items[" + i + "].Id")" value="@item.Id" />
+                        <input type="number" class="esh-basket-input" min="0" name="@("Items[" + i + "].Quantity")" value="@item.Quantity" />
                     </section>
                     <section class="esh-basket-item esh-basket-item--middle esh-basket-item--mark col-xs-2">$ @Math.Round(item.Quantity * item.UnitPrice, 2).ToString("N2")</section>
                 </div>
                 <div class="row">
 
                 </div>
-                    </article>
-                    @*<div class="esh-catalog-item col-md-4">
+            </article> @*<div class="esh-catalog-item col-md-4">
                             @item.ProductId
-            </div>*@
-
-                }
+                        </div>*@                }
 
                 <div class="container">
                     <article class="esh-basket-titles esh-basket-titles--clean row">
@@ -77,16 +75,15 @@
                                 asp-page-handler="Update">
                             [ Update ]
                         </button>
-                        @{
-                            var data = new Dictionary<string, string>
+                        @{ var data = new Dictionary<string, string>
                                                                                             {
                                 { Constants.BASKET_ID, Model.BasketModel.Id.ToString() },
-                            };
-                        }
+                            }; }
+
                             <input type="submit" asp-page="Checkout"
                                    class="btn esh-basket-checkout"
-                               asp-all-route-data=data
                                    value="[ Checkout ]" name="action" />
+
                     </section>
                 </div>
             </div>

src/Web/Pages/Basket/Index.cshtml.cs

@@ -8,6 +8,7 @@ using Microsoft.eShopWeb.Web.Interfaces;
 using Microsoft.eShopWeb.Web.ViewModels;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 
 namespace Microsoft.eShopWeb.Web.Pages.Basket
@@ -50,10 +51,17 @@ namespace Microsoft.eShopWeb.Web.Pages.Basket
             return RedirectToPage();
         }
 
-        public async Task OnPostUpdate(Dictionary<string, int> items)
+        public async Task OnPostUpdate(IEnumerable<BasketItemViewModel> items)
         {
             await SetBasketModelAsync();
-            await _basketService.SetQuantities(BasketModel.Id, items);
+
+            if (!ModelState.IsValid)
+            {
+                return;
+            }
+
+            var updateModel = items.ToDictionary(b => b.Id.ToString(), b => b.Quantity);
+            await _basketService.SetQuantities(BasketModel.Id, updateModel);
 
             await SetBasketModelAsync();
         }

tests/UnitTests/ApplicationCore/Entities/BasketTests/BasketAddItem.cs

@@ -1,4 +1,5 @@
 using Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate;
+using System;
 using System.Linq;
 using Xunit;
 
@@ -64,5 +65,22 @@ namespace Microsoft.eShopWeb.UnitTests.ApplicationCore.Entities.BasketTests
 
             Assert.Equal(0, basket.Items.Count);
         }
+
+        [Fact]
+        public void CantAddItemWithNegativeQuantity()
+        {
+            var basket = new Basket(_buyerId);
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => basket.AddItem(_testCatalogItemId, _testUnitPrice, -1));
+        }
+
+        [Fact]
+        public void CantModifyQuantityToNegativeNumber()
+        {
+            var basket = new Basket(_buyerId);
+            basket.AddItem(_testCatalogItemId, _testUnitPrice);
+
+            Assert.Throws<ArgumentOutOfRangeException>(() => basket.AddItem(_testCatalogItemId, _testUnitPrice, -2));
+        }
     }
 }