Re-adding BasketQueryService

src/ApplicationCore/Interfaces/IBasketQueryService.cs

@@ -0,0 +1,12 @@
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.ApplicationCore.Interfaces;
+
+/// <summary>
+/// Specific query used to fetch count without running in memory
+/// </summary>
+public interface IBasketQueryService
+{
+    Task<int> CountTotalBasketItems(string username);
+}
+

src/Infrastructure/Data/Queries/BasketQueryService.cs

@@ -0,0 +1,31 @@
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.eShopWeb.ApplicationCore.Interfaces;
+
+namespace Microsoft.eShopWeb.Infrastructure.Data.Queries;
+
+public class BasketQueryService : IBasketQueryService
+{
+    private readonly CatalogContext _dbContext;
+
+    public BasketQueryService(CatalogContext dbContext)
+    {
+        _dbContext = dbContext;
+    }
+
+    /// <summary>
+    /// This method performs the sum on the database rather than in memory
+    /// </summary>
+    /// <param name="username"></param>
+    /// <returns></returns>
+    public async Task<int> CountTotalBasketItems(string username)
+    {
+        var totalItems = await _dbContext.Baskets
+            .Where(basket => basket.BuyerId == username)
+            .SelectMany(item => item.Items)
+            .SumAsync(sum => sum.Quantity);
+
+        return totalItems;
+    }
+}

src/Web/Configuration/ConfigureCoreServices.cs

@@ -1,6 +1,7 @@
 using Microsoft.eShopWeb.ApplicationCore.Interfaces;
 using Microsoft.eShopWeb.ApplicationCore.Services;
 using Microsoft.eShopWeb.Infrastructure.Data;
+using Microsoft.eShopWeb.Infrastructure.Data.Queries;
 using Microsoft.eShopWeb.Infrastructure.Logging;
 using Microsoft.eShopWeb.Infrastructure.Services;
 using Microsoft.Extensions.Configuration;
@@ -18,6 +19,7 @@ public static class ConfigureCoreServices
 
         services.AddScoped<IBasketService, BasketService>();
         services.AddScoped<IOrderService, OrderService>();
+        services.AddScoped<IBasketQueryService, BasketQueryService>();
         services.AddSingleton<IUriComposer>(new UriComposer(configuration.Get<CatalogSettings>()));
         services.AddScoped(typeof(IAppLogger<>), typeof(LoggerAdapter<>));
         services.AddTransient<IEmailSender, EmailSender>();

src/Web/Interfaces/IBasketViewModelService.cs

@@ -7,5 +7,6 @@ namespace Microsoft.eShopWeb.Web.Interfaces;
 public interface IBasketViewModelService
 {
     Task<BasketViewModel> GetOrCreateBasketForUser(string userName);
+    Task<int> CountTotalBasketItems(string username);
     Task<BasketViewModel> Map(Basket basket);
 }

src/Web/Pages/Shared/Components/BasketComponent/Basket.cs

@@ -2,27 +2,21 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Mvc;
-using Microsoft.eShopWeb.ApplicationCore.Interfaces;
-using Microsoft.eShopWeb.ApplicationCore.Specifications;
 using Microsoft.eShopWeb.Infrastructure.Identity;
 using Microsoft.eShopWeb.Web.Interfaces;
 using Microsoft.eShopWeb.Web.ViewModels;
-using BasketEntity = Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate.Basket;
 
 namespace Microsoft.eShopWeb.Web.Pages.Shared.Components.BasketComponent;
 
 public class Basket : ViewComponent
 {
-    private readonly IBasketViewModelService _basketViewModelService;
-    private readonly IReadRepository<BasketEntity> _basketRepository;
+    private readonly IBasketViewModelService _basketService;
     private readonly SignInManager<ApplicationUser> _signInManager;
 
-    public Basket(IBasketViewModelService basketViewModelService,
-        IReadRepository<BasketEntity> basketRepository,
-        SignInManager<ApplicationUser> signInManager)
+    public Basket(IBasketViewModelService basketService,
+                    SignInManager<ApplicationUser> signInManager)
     {
-        _basketViewModelService = basketViewModelService;
-        _basketRepository = basketRepository;
+        _basketService = basketService;
         _signInManager = signInManager;
     }
 
@@ -39,26 +33,18 @@ public class Basket : ViewComponent
     {
         if (_signInManager.IsSignedIn(HttpContext.User))
         {
-            var userNameSpec = new BasketWithItemsSpecification(User.Identity.Name);
-            
-            var userBasket = await _basketRepository.GetBySpecAsync(userNameSpec);
-            if (userBasket == null) return 0;
-            return userBasket.TotalItems;
+            return await _basketService.CountTotalBasketItems(User.Identity.Name);
         }
 
         string anonymousId = GetAnnonymousIdFromCookie();
         if (anonymousId == null)
             return 0;
 
-        var anonymousSpec = new BasketWithItemsSpecification(anonymousId);
-        var anonymousBasket = await _basketRepository.GetBySpecAsync(anonymousSpec);
-        if (anonymousBasket == null) return 0;
-        return anonymousBasket.TotalItems;
+        return await _basketService.CountTotalBasketItems(anonymousId);
     }
 
     private string GetAnnonymousIdFromCookie()
     {
-        // TODO: Add a prefix to anonymous cookie values so they cannot collide with user names
         if (Request.Cookies.ContainsKey(Constants.BASKET_COOKIENAME))
         {
             var id = Request.Cookies[Constants.BASKET_COOKIENAME];

src/Web/Services/BasketViewModelService.cs

@@ -14,14 +14,17 @@ public class BasketViewModelService : IBasketViewModelService
 {
     private readonly IRepository<Basket> _basketRepository;
     private readonly IUriComposer _uriComposer;
-    private readonly IReadRepository<CatalogItem> _itemRepository;
+    private readonly IBasketQueryService _basketQueryService;
+    private readonly IRepository<CatalogItem> _itemRepository;
 
     public BasketViewModelService(IRepository<Basket> basketRepository,
-        IReadRepository<CatalogItem> itemRepository,
-        IUriComposer uriComposer)
+        IRepository<CatalogItem> itemRepository,
+        IUriComposer uriComposer,
+        IBasketQueryService basketQueryService)
     {
         _basketRepository = basketRepository;
         _uriComposer = uriComposer;
+        _basketQueryService = basketQueryService;
         _itemRepository = itemRepository;
     }
 
@@ -83,4 +86,11 @@ public class BasketViewModelService : IBasketViewModelService
             Items = await GetBasketItems(basket.Items)
         };
     }
+
+    public async Task<int> CountTotalBasketItems(string username)
+    {
+        var counter = await _basketQueryService.CountTotalBasketItems(username);
+
+        return counter;
+    }
 }