Clean Architecture: replace the ToDoApp sample with EventTicketing on .NET 10 (#2238)

The article is rewritten around a small ticket-reservation API: Domain, Application,
Infrastructure and Api projects, the Result pattern mapped to ProblemDetails, plain
use-case handlers (no MediatR), EF Core with SQLite, unit tests with fakes, and
NetArchTest architecture tests that enforce the Dependency Rule.

Targets net10.0. Build: 0 warnings. Tests: 6 unit, 3 architecture, all passing.

Author: vladimir-pecanac-main

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/Contracts/ReserveTicketsRequest.cs

@@ -0,0 +1,5 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace EventTicketing.Api.Contracts;
+
+public sealed record ReserveTicketsRequest([property: Range(1, 20)] int Quantity);

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/Endpoints/EventEndpoints.cs

@@ -0,0 +1,37 @@
+using EventTicketing.Api.Contracts;
+using EventTicketing.Api.Extensions;
+using EventTicketing.Application.Events;
+
+namespace EventTicketing.Api.Endpoints;
+
+public static class EventEndpoints
+{
+    public static IEndpointRouteBuilder MapEventEndpoints(this IEndpointRouteBuilder app)
+    {
+        var events = app.MapGroup("/api/events");
+
+        events.MapGet("/{eventId:int}", async (
+            int eventId,
+            GetEventAvailabilityHandler handler,
+            CancellationToken cancellationToken) =>
+        {
+            var result = await handler.HandleAsync(new GetEventAvailabilityQuery(eventId), cancellationToken);
+
+            return result.IsSuccess ? Results.Ok(result.Value) : result.ToProblem();
+        });
+
+        events.MapPost("/{eventId:int}/reservations", async (
+            int eventId,
+            ReserveTicketsRequest request,
+            ReserveTicketsHandler handler,
+            CancellationToken cancellationToken) =>
+        {
+            var command = new ReserveTicketsCommand(eventId, request.Quantity);
+            var result = await handler.HandleAsync(command, cancellationToken);
+
+            return result.IsSuccess ? Results.Ok(result.Value) : result.ToProblem();
+        });
+
+        return app;
+    }
+}

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/EventTicketing.Api.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <ItemGroup>
+    <ProjectReference Include="..\EventTicketing.Application\EventTicketing.Application.csproj" />
+    <ProjectReference Include="..\EventTicketing.Infrastructure\EventTicketing.Infrastructure.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.12" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/Extensions/ResultExtensions.cs

@@ -0,0 +1,25 @@
+using EventTicketing.Domain.Common;
+
+namespace EventTicketing.Api.Extensions;
+
+public static class ResultExtensions
+{
+    public static IResult ToProblem(this Result result)
+    {
+        if (result.IsSuccess)
+            throw new InvalidOperationException("A successful result is not a problem.");
+
+        var statusCode = result.Error.Type switch
+        {
+            ErrorType.Validation => StatusCodes.Status400BadRequest,
+            ErrorType.NotFound => StatusCodes.Status404NotFound,
+            ErrorType.Conflict => StatusCodes.Status409Conflict,
+            _ => StatusCodes.Status500InternalServerError
+        };
+
+        return TypedResults.Problem(
+            statusCode: statusCode,
+            title: result.Error.Code,
+            detail: result.Error.Description);
+    }
+}

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/Program.cs

@@ -0,0 +1,27 @@
+using EventTicketing.Api.Endpoints;
+using EventTicketing.Application;
+using EventTicketing.Infrastructure;
+using EventTicketing.Infrastructure.Persistence;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddApplication();
+builder.Services.AddInfrastructure(builder.Configuration.GetConnectionString("Ticketing")!);
+
+builder.Services.AddProblemDetails();
+builder.Services.AddValidation();
+builder.Services.AddOpenApi();
+
+var app = builder.Build();
+
+app.UseExceptionHandler();
+
+if (app.Environment.IsDevelopment())
+{
+    app.MapOpenApi();
+    await app.Services.SeedDatabaseAsync();
+}
+
+app.MapEventEndpoints();
+
+app.Run();

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/Properties/launchSettings.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "applicationUrl": "http://localhost:5000",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

…rchitecture/ToDoApp.API/appsettings.json …cketing.Api/appsettings.Development.jsoncsharp-architectural-patterns/CleanArchitecture/ToDoApp.API/appsettings.json renamed to csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/appsettings.Development.json csharp-architectural-patterns/CleanArchitecture/ToDoApp.API/appsettings.json renamed to csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/appsettings.Development.json

@@ -4,6 +4,5 @@
       "Default": "Information",
       "Microsoft.AspNetCore": "Warning"
     }
-  },
-  "AllowedHosts": "*"
+  }
 }

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Api/appsettings.json

@@ -0,0 +1,12 @@
+{
+  "ConnectionStrings": {
+    "Ticketing": "Data Source=tickets.db"
+  },
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Application/Abstractions/IUnitOfWork.cs

@@ -0,0 +1,6 @@
+namespace EventTicketing.Application.Abstractions;
+
+public interface IUnitOfWork
+{
+    Task SaveChangesAsync(CancellationToken cancellationToken = default);
+}

csharp-architectural-patterns/CleanArchitecture/EventTicketing.Application/DependencyInjection.cs

@@ -0,0 +1,15 @@
+using EventTicketing.Application.Events;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace EventTicketing.Application;
+
+public static class DependencyInjection
+{
+    public static IServiceCollection AddApplication(this IServiceCollection services)
+    {
+        services.AddScoped<ReserveTicketsHandler>();
+        services.AddScoped<GetEventAvailabilityHandler>();
+
+        return services;
+    }
+}