Add a RatingsService and use it from the frontend

samples/eShopLite/ApiGateway/appsettings.json

@@ -25,6 +25,15 @@
         "Transforms": [
           { "PathRemovePrefix": "/basket" }
         ]
+      },
+      "rating": {
+        "ClusterId": "rating",
+        "Match": {
+          "Path": "/rating/{**catch-all}"
+        },
+        "Transforms": [
+          { "PathRemovePrefix": "/rating" }
+        ]
       }
     },
     "Clusters": {
@@ -43,6 +52,14 @@
             "Health": "http://basketservice/readiness"
           }
         }
+      },
+      "rating": {
+        "Destinations": {
+          "rating": {
+            "Address": "http://ratingservice",
+            "Health": "http://ratingservice/readiness"
+          }
+        }
       }
     }
   }

samples/eShopLite/AppHost/AppHost.csproj

@@ -18,6 +18,7 @@
     <ProjectReference Include="..\CatalogService\CatalogService.csproj" />
     <ProjectReference Include="..\MyFrontend\MyFrontend.csproj" />
     <ProjectReference Include="..\OrderProcessor\OrderProcessor.csproj" />
+    <ProjectReference Include="..\RatingsService\RatingsService.csproj" />
   </ItemGroup>
 
 </Project>

samples/eShopLite/AppHost/Program.cs

@@ -2,13 +2,18 @@
 
 builder.AddAzureProvisioning();
 
-var catalogdb = builder.AddAzureCosmosDB("cosmosdb").AddDatabase("catalogdb");
+var cosmosdb = builder.AddAzureCosmosDB("cosmosdb");
+var catalogdb = cosmosdb.AddDatabase("catalogdb");
+var ratingsdb = cosmosdb.AddDatabase("ratingsdb");
 
 var basketCache = builder.AddRedisContainer("basketCache");
 
 var catalogService = builder.AddProject<Projects.CatalogService>("catalogservice")
     .WithReference(catalogdb);
 
+var ratingsService = builder.AddProject<Projects.RatingsService>("ratingsservice")
+    .WithReference(ratingsdb);
+
 var messaging = builder.AddRabbitMQContainer("messaging");
 
 var basketService = builder.AddProject<Projects.BasketService>("basketservice")
@@ -17,15 +22,17 @@
 
 builder.AddProject<Projects.MyFrontend>("frontend")
        .WithReference(basketService)
-       .WithReference(catalogService.GetEndpoint("http"));
+       .WithReference(catalogService.GetEndpoint("http"))
+       .WithReference(ratingsService.GetEndpoint("http"));
 
 builder.AddProject<Projects.OrderProcessor>("orderprocessor")
        .WithReference(messaging)
        .WithLaunchProfile("OrderProcessor");
 
 builder.AddProject<Projects.ApiGateway>("apigateway")
        .WithReference(basketService)
-       .WithReference(catalogService);
+       .WithReference(catalogService)
+       .WithReference(ratingsService);
 
 builder.AddProject<Projects.CatalogDb>("catalogdbapp")
        .WithReference(catalogdb);

samples/eShopLite/MyFrontend/Components/Pages/Home.razor

@@ -2,6 +2,7 @@
 @attribute [StreamRendering(true)]
 
 @inject CatalogServiceClient CatalogService
+@inject RatingServiceClient RatingService
 
 <PageTitle>eShopLite Product Catalog</PageTitle>
 
@@ -34,6 +35,7 @@
                                 {
                                     <AddToCart Item="item" />
                                 }
+                                <p class="item-rating pointer-events-none">@ratings[item.Id]</p>
                             </div>
                         </div>
                     </div>
@@ -65,6 +67,7 @@
     bool basketIsAvailable;
     Catalog? catalog;
     PaginationInfo paginationInfo = new(FirstId: 0, NextId: 0, HasPreviousPage: false, HasNextPage: false);
+    Dictionary<int, string> ratings = new();
 
     [SupplyParameterFromQuery]
     public int? Before { get; set; }
@@ -81,6 +84,18 @@
             return;
         }
 
+        var idsAndTasks = new List<(int id, Task<string> task)>();
+        foreach (var item in catalog.Data)
+        {
+            idsAndTasks.Add((item.Id, RatingService.GetRatingAsync(item.Id)));
+        }
+        await Task.WhenAll(idsAndTasks.Select(i => i.task));
+
+        foreach (var (id, task) in idsAndTasks)
+        {
+            ratings[id] = task.Result;
+        }
+
         paginationInfo = new PaginationInfo(catalog.FirstId, catalog.NextId, catalog.FirstId > 1, !catalog.IsLastPage);
     }
 

samples/eShopLite/MyFrontend/Program.cs

@@ -9,6 +9,8 @@
 builder.Services.AddHttpForwarderWithServiceDiscovery();
 
 builder.Services.AddHttpClient<CatalogServiceClient>(c => c.BaseAddress = new("http://catalogservice"));
+//builder.Services.AddHttpClient<RatingServiceClient>(c => c.BaseAddress = new("http://ratingservice"));
+builder.Services.AddHttpClient<RatingServiceClient>(c => c.BaseAddress = new("http://localhost:5419"));
 
 builder.Services.AddSingleton<BasketServiceClient>()
                 .AddGrpcClient<Basket.BasketClient>(o => o.Address = new("http://basketservice"));

samples/eShopLite/MyFrontend/Services/RatingServiceClient.cs

@@ -0,0 +1,14 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Globalization;
+
+namespace MyFrontend.Services;
+
+public class RatingServiceClient(HttpClient client)
+{
+    public Task<string> GetRatingAsync(int productId)
+    {
+        return client.GetStringAsync($"averagerating/{productId.ToString(CultureInfo.InvariantCulture)}");
+    }
+}

samples/eShopLite/RatingsService/Program.cs

@@ -1,14 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Globalization;
+using Microsoft.Azure.Cosmos;
+using Microsoft.Azure.Cosmos.Linq;
+using RatingsService;
 
 var builder = WebApplication.CreateBuilder(args);
 
 builder.AddServiceDefaults();
 
+builder.AddAzureCosmosDB("ratingsdb");
+
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddProblemDetails();
 builder.Services.AddSwaggerGen();
 
 var app = builder.Build();
 
+var cc = app.Services.GetRequiredService<CosmosClient>();
+var dbr = await cc.CreateDatabaseIfNotExistsAsync("ratingsdb");
+var cr = await dbr.Database.CreateContainerIfNotExistsAsync("ratings", "/ProductId");
+var ir = await cr.Container.UpsertItemAsync(
+    new Rating
+    {
+        RatingId = "0",
+        ProductId = "1",
+        RatingValue = 5,
+        User = "kevinpi",
+        Review = "Great product!"
+    });
+
 if (app.Environment.IsDevelopment())
 {
     app.UseSwagger();
@@ -19,6 +41,33 @@
     app.UseExceptionHandler();
 }
 
+app.MapGet("averagerating/{productId}", async (string productId, CosmosClient cosmosClient) =>
+{
+    var container = cosmosClient.GetContainer("ratingsdb", "ratings");
+
+    var feed = container.GetItemLinqQueryable<Rating>(true)
+        .Where(r => r.ProductId == productId)
+        .ToFeedIterator();
+
+    var ratings = new List<Rating>();
+    var sum = 0f;
+    var count = 0;
+    while (feed.HasMoreResults)
+    {
+        foreach (var r in await feed.ReadNextAsync())
+        {
+            sum += r.RatingValue;
+            count++;
+        }
+    }
+
+    var result = count > 0
+        ? (sum / count).ToString("0.00", CultureInfo.InvariantCulture) + " / 5"
+        : "no ratings";
+
+    return result;
+});
+
 app.MapDefaultEndpoints();
 
 app.Run();

samples/eShopLite/RatingsService/Rating.cs

@@ -0,0 +1,28 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.ComponentModel.DataAnnotations;
+using Newtonsoft.Json;
+
+namespace RatingsService;
+
+public class Rating
+{
+    /// <summary>A unique id for this rating.</summary>
+    [Required, JsonProperty("id")]
+    public string RatingId { get; set; } = "";
+
+    /// <summary>The ProductId that this rating is for.</summary>
+    [Required]
+    public string ProductId { get; set; } = "";
+
+    /// <summary>The value of this rating (from 1 to 5).</summary>
+    [Range(1, 5)]
+    public int RatingValue { get; set; }
+
+    /// <summary>The user who gave this rating (optional).</summary>
+    public string? User { get; set; }
+
+    /// <summary>The text of the review (optional).</summary>
+    public string? Review { get; set; }
+}

samples/eShopLite/RatingsService/RatingsService.csproj

@@ -14,6 +14,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\..\src\Components\Aspire.Microsoft.Azure.Cosmos\Aspire.Microsoft.Azure.Cosmos.csproj" />
     <ProjectReference Include="..\ServiceDefaults\ServiceDefaults.csproj" />
   </ItemGroup>