Cleanup some EF TODOs

src/MusicStore/Components/GenreMenuComponent.cs

@@ -26,16 +26,13 @@ namespace MusicStore.Components
 
         private async Task<List<Genre>> GetGenres()
         {
-            // TODO [EF] We don't query related data as yet, so the OrderByDescending isn't doing anything
-            //var genres = _dbContext.Genres
-            //.OrderByDescending(
-            //    g => g.Albums.Sum(
-            //    a => a.OrderDetails.Sum(
-            //    od => od.Quantity)))
-            //.Take(9)
-            //.ToList();
-
-            return await DbContext.Genres.Take(9).ToListAsync();
+            return await DbContext.Genres
+                .Include(g => g.Albums).ThenInclude(a => a.OrderDetails)
+                // TODO use nested sum https://github.com/aspnet/EntityFramework/issues/3792
+                //.OrderByDescending(
+                //    g => g.Albums.Sum(a => a.OrderDetails.Sum(od => od.Quantity)))
+                .Take(9)
+                .ToListAsync();
         }
     }
 }

src/MusicStore/Controllers/HomeController.cs

@@ -60,9 +60,8 @@ namespace MusicStore.Controllers
             // Group the order details by album and return
             // the albums with the highest count
 
-            // TODO [EF] We don't query related data as yet, so the OrderByDescending isn't doing anything
             return await dbContext.Albums
-                .OrderByDescending(a => a.OrderDetails.Count())
+                .OrderByDescending(a => a.OrderDetails.Count)
                 .Take(count)
                 .ToListAsync();
         }

src/MusicStore/Models/CartItem.cs

@@ -5,6 +5,7 @@ namespace MusicStore.Models
 {
     public class CartItem
     {
+        [Key]
         public int CartItemId { get; set; }
 
         [Required]

src/MusicStore/Models/MusicStoreContext.cs

@@ -13,20 +13,5 @@ namespace MusicStore.Models
         public DbSet<Genre> Genres { get; set; }
         public DbSet<CartItem> CartItems { get; set; }
         public DbSet<OrderDetail> OrderDetails { get; set; }
-
-        protected override void OnModelCreating(ModelBuilder builder)
-        {
-            builder.Entity<CartItem>().HasKey(b => b.CartItemId);
-
-            // TODO: Remove when explicit values insertion removed.
-            builder.Entity<Artist>().Property(a => a.ArtistId).ValueGeneratedNever();
-            builder.Entity<Genre>().Property(g => g.GenreId).ValueGeneratedNever();
-
-            //Deleting an album fails with this relation
-            builder.Entity<Album>().Ignore(a => a.OrderDetails);
-            builder.Entity<OrderDetail>().Ignore(od => od.Album);
-
-            base.OnModelCreating(builder);
-        }
     }
 }

src/MusicStore/Models/SampleData.cs

@@ -913,12 +913,9 @@ namespace MusicStore.Models
                         new Artist { Name = "אריק אינשטיין"}
                     };
 
-                    // TODO [EF] Swap to store generated keys when available
-                    int artistId = 1;
                     artists = new Dictionary<string, Artist>();
                     foreach (Artist artist in artistsList)
                     {
-                        artist.ArtistId = artistId++;
                         artists.Add(artist.Name, artist);
                     }
                 }
@@ -954,15 +951,9 @@ namespace MusicStore.Models
                     };
 
                     genres = new Dictionary<string, Genre>();
-                    // TODO [EF] Swap to store generated keys when available
-                    int genreId = 1;
+
                     foreach (Genre genre in genresList)
                     {
-                        genre.GenreId = genreId++;
-
-                        // TODO [EF] Remove when null values are supported by update pipeline
-                        genre.Description = genre.Name + " is great music (if you like it).";
-
                         genres.Add(genre.Name, genre);
                     }
                 }

src/MusicStore/Models/ShoppingCart.cs

@@ -10,25 +10,25 @@ namespace MusicStore.Models
     public class ShoppingCart
     {
         private readonly MusicStoreContext _dbContext;
-        private string ShoppingCartId { get; set; }
+        private readonly string _shoppingCartId;
 
-        public ShoppingCart(MusicStoreContext dbContext)
+        private ShoppingCart(MusicStoreContext dbContext, string id)
         {
             _dbContext = dbContext;
+            _shoppingCartId = id;
         }
 
-        public static ShoppingCart GetCart(MusicStoreContext db, HttpContext context)
-        {
-            var cart = new ShoppingCart(db);
-            cart.ShoppingCartId = cart.GetCartId(context);
-            return cart;
-        }
+        public static ShoppingCart GetCart(MusicStoreContext db, HttpContext context) 
+            => GetCart(db, GetCartId(context));
+
+        public static ShoppingCart GetCart(MusicStoreContext db, string cartId)
+            => new ShoppingCart(db, cartId);
 
         public void AddToCart(Album album)
         {
             // Get the matching cart and album instances
             var cartItem = _dbContext.CartItems.SingleOrDefault(
-                c => c.CartId == ShoppingCartId
+                c => c.CartId == _shoppingCartId
                 && c.AlbumId == album.AlbumId);
 
             if (cartItem == null)
@@ -37,7 +37,7 @@ namespace MusicStore.Models
                 cartItem = new CartItem
                 {
                     AlbumId = album.AlbumId,
-                    CartId = ShoppingCartId,
+                    CartId = _shoppingCartId,
                     Count = 1,
                     DateCreated = DateTime.Now
                 };
@@ -55,7 +55,7 @@ namespace MusicStore.Models
         {
             // Get the cart
             var cartItem = _dbContext.CartItems.Single(
-                cart => cart.CartId == ShoppingCartId
+                cart => cart.CartId == _shoppingCartId
                 && cart.CartItemId == id);
 
             int itemCount = 0;
@@ -76,39 +76,45 @@ namespace MusicStore.Models
             return itemCount;
         }
 
-        public void EmptyCart()
+        public async void EmptyCart()
         {
-            var cartItems = _dbContext.CartItems.Where(cart => cart.CartId == ShoppingCartId).ToArray();
+            var cartItems = await _dbContext
+                .CartItems
+                .Where(cart => cart.CartId == _shoppingCartId)
+                .ToArrayAsync();
+
             _dbContext.CartItems.RemoveRange(cartItems);
         }
 
-        public async Task<List<CartItem>> GetCartItems()
+        public Task<List<CartItem>> GetCartItems()
         {
-            return await _dbContext.CartItems.
-                Where(cart => cart.CartId == ShoppingCartId).
+            return _dbContext.CartItems.
+                Where(cart => cart.CartId == _shoppingCartId).
                 Include(c => c.Album).
                 ToListAsync();
         }
 
-        public async Task<int> GetCount()
+        public Task<int> GetCount()
         {
             // Get the count of each item in the cart and sum them up
-            return await (from cartItem in _dbContext.CartItems
-                          where cartItem.CartId == ShoppingCartId
-                          select cartItem.Count).SumAsync();
+            return _dbContext
+                .CartItems
+                .Where(c => c.CartId == _shoppingCartId)
+                .Select(c => c.Count)
+                .SumAsync();
         }
 
-        public async Task<decimal> GetTotal()
+        public Task<decimal> GetTotal()
         {
             // Multiply album price by count of that album to get 
             // the current price for each of those albums in the cart
             // sum all album price totals to get the cart total
 
-            // TODO: Use nav prop traversal instead of joins (EF #https://github.com/aspnet/EntityFramework/issues/325)
-            return await (from cartItem in _dbContext.CartItems
-                          join album in _dbContext.Albums on cartItem.AlbumId equals album.AlbumId
-                          where cartItem.CartId == ShoppingCartId
-                          select cartItem.Count * album.Price).SumAsync();
+            return _dbContext.CartItems
+                .Include(c => c.Album)
+                .Where(c => c.CartId == _shoppingCartId)
+                .Select(c => c.Album.Price * c.Count)
+                .SumAsync();
         }
 
         public async Task<int> CreateOrder(Order order)
@@ -148,7 +154,7 @@ namespace MusicStore.Models
         }
 
         // We're using HttpContextBase to allow access to sessions.
-        private string GetCartId(HttpContext context)
+        private static string GetCartId(HttpContext context)
         {
             var cartId = context.Session.GetString("Session");
 

test/MusicStore.Test/Models/ShoppingCartTest.cs

@@ -0,0 +1,55 @@
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using MusicStore.Models;
+using Xunit;
+
+namespace MusicStore.Test
+{
+    public class ShoppingCartTest : IClassFixture<ShoppingCartFixture>
+    {
+        private readonly ShoppingCartFixture _fixture;
+
+        public ShoppingCartTest(ShoppingCartFixture fixture)
+        {
+            _fixture = fixture;
+        }
+
+        [Fact]
+        public async void ComputesTotal()
+        {
+            var cartId = Guid.NewGuid().ToString();
+            using (var db = _fixture.CreateContext())
+            {
+                var a = db.Albums.Add(
+                    new Album
+                    {
+                        Price = 15.99m
+                    }).Entity;
+
+                db.CartItems.Add(new CartItem { Album = a, Count = 2, CartId = cartId });
+
+                db.SaveChanges();
+
+                Assert.Equal(31.98m, await ShoppingCart.GetCart(db, cartId).GetTotal());
+            }
+        }
+    }
+
+    public class ShoppingCartFixture
+    {
+        private readonly IServiceProvider _serviceProvider;
+
+        public ShoppingCartFixture()
+        {
+            var services = new ServiceCollection();
+            services.AddEntityFramework()
+                .AddInMemoryDatabase()
+                .AddDbContext<MusicStoreContext>(options => options.UseInMemoryDatabase());
+            _serviceProvider = services.BuildServiceProvider();
+        }
+
+        public virtual MusicStoreContext CreateContext()
+            => _serviceProvider.GetRequiredService<MusicStoreContext>();
+    }
+}