Added example of MapCommand for extreme endpoints handling

Author: oskardudycz

Sample/Warehouse/Warehouse.Api.Tests/Products/GettingProductDetails/GetProductDetailsTests.cs

@@ -1,13 +1,11 @@
 using System;
-using System.Collections.Generic;
 using System.Net;
 using System.Threading.Tasks;
 using Core.Testing;
 using FluentAssertions;
 using Microsoft.AspNetCore.Hosting;
+using Warehouse.Api.Tests.Products.RegisteringProduct;
 using Warehouse.Products.GettingProductDetails;
-using Warehouse.Products.GettingProducts;
-using Warehouse.Products.RegisteringProduct;
 using Xunit;
 
 namespace Warehouse.Api.Tests.Products.GettingProductDetails

Sample/Warehouse/Warehouse.Api.Tests/Products/GettingProducts/GetProductsTests.cs

@@ -6,8 +6,8 @@
 using Core.Testing;
 using FluentAssertions;
 using Microsoft.AspNetCore.Hosting;
+using Warehouse.Api.Tests.Products.RegisteringProduct;
 using Warehouse.Products.GettingProducts;
-using Warehouse.Products.RegisteringProduct;
 using Xunit;
 
 namespace Warehouse.Api.Tests.Products.GettingProducts

Sample/Warehouse/Warehouse/Core/Commands/ICommandHandler.cs

@@ -8,7 +8,19 @@ namespace Warehouse.Core.Commands
 {
     public interface ICommandHandler<in T>
     {
-        ValueTask Handle(T command, CancellationToken token);
+        ValueTask<CommandResult> Handle(T command, CancellationToken token);
+    }
+
+    public record CommandResult
+    {
+        public object? Result { get; }
+
+        private CommandResult(object? result = null)
+            => Result = result;
+
+        public static CommandResult None => new();
+
+        public static CommandResult Of(object result) => new(result);
     }
 
     public static class CommandHandlerConfiguration
@@ -37,7 +49,7 @@ public static ICommandHandler<T> GetCommandHandler<T>(this HttpContext context)
             => context.RequestServices.GetRequiredService<ICommandHandler<T>>();
 
 
-        public static ValueTask SendCommand<T>(this HttpContext context, T command)
+        public static ValueTask<CommandResult> SendCommand<T>(this HttpContext context, T command)
             => context.GetCommandHandler<T>()
                 .Handle(command, context.RequestAborted);
     }

Sample/Warehouse/Warehouse/Core/Extensions/EndpointsExtensions.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Net;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
+using Warehouse.Core.Commands;
+
+namespace Warehouse.Core.Extensions
+{
+internal static class EndpointsExtensions
+{
+    internal static IEndpointRouteBuilder MapCommand<TRequest>(
+        this IEndpointRouteBuilder endpoints,
+        HttpMethod httpMethod,
+        string url,
+        HttpStatusCode statusCode = HttpStatusCode.OK)
+    {
+        endpoints.MapMethods(url, new []{httpMethod.ToString()} , async context =>
+        {
+            var command = await context.FromBody<TRequest>();
+
+            var commandResult = await context.SendCommand(command);
+
+            if (commandResult == CommandResult.None)
+            {
+                context.Response.StatusCode = (int)statusCode;
+                return;
+            }
+
+            await context.ReturnJSON(commandResult.Result, statusCode);
+        });
+
+        return endpoints;
+    }
+}
+}

Sample/Warehouse/Warehouse/Core/Extensions/HttpExtensions.cs

@@ -2,6 +2,7 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Net;
+using System.Text.Json;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Primitives;

Sample/Warehouse/Warehouse/Core/Primitives/MappingExtensions.cs

@@ -14,7 +14,7 @@ public static T AssertNotNull<T>(this T? value, string? paramName = null)
         }
 
         public static string AssertNotEmpty(this string? value, string? paramName = null)
-            => string.IsNullOrWhiteSpace(value) ? value! : throw new ArgumentOutOfRangeException(paramName);
+            => !string.IsNullOrWhiteSpace(value) ? value! : throw new ArgumentOutOfRangeException(paramName);
 
         public static T AssertNotEmpty<T>(this T value, string? paramName = null)
             where T : struct

Sample/Warehouse/Warehouse/Products/Configuration.cs

@@ -1,9 +1,12 @@
 using System.Collections.Generic;
+using System.Net;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Warehouse.Core.Commands;
 using Warehouse.Core.Entities;
+using Warehouse.Core.Extensions;
 using Warehouse.Core.Queries;
 using Warehouse.Products.GettingProductDetails;
 using Warehouse.Products.GettingProducts;
@@ -35,7 +38,7 @@ public static IServiceCollection AddProductServices(this IServiceCollection serv
 
         public static IEndpointRouteBuilder UseProductsEndpoints(this IEndpointRouteBuilder endpoints) =>
             endpoints
-                .UseRegisterProductEndpoint()
+                .MapCommand<RegisterProduct>(HttpMethod.Post, "/api/products", HttpStatusCode.Created)
                 .UseGetProductsEndpoint()
                 .UseGetProductDetailsEndpoint();
 

Sample/Warehouse/Warehouse/Products/GettingProductDetails/GetProductDetails.cs

@@ -19,7 +19,8 @@ public HandleGetProductDetails(IQueryable<Product> products)
 
         public async ValueTask<ProductDetails?> Handle(GetProductDetails query, CancellationToken ct)
         {
-            // await is needed because of https://github.com/dotnet/efcore/issues/21793#issuecomment-667096367
+            // btw. SingleOrDefaultAsync do not work properly with NullableReferenceTypes
+            // See more in: https://github.com/dotnet/efcore/issues/21793#issuecomment-667096367
             var product = await products
                 .SingleOrDefaultAsync(p => p.Id == query.ProductId, ct);
 

Sample/Warehouse/Warehouse/Products/RegisteringProduct/RegisterProduct.cs

@@ -1,12 +1,14 @@
 using System;
+using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
 using Warehouse.Core.Commands;
+using Warehouse.Core.Primitives;
 using Warehouse.Products.Primitives;
 
 namespace Warehouse.Products.RegisteringProduct
 {
-    internal class HandleRegisterProduct : ICommandHandler<RegisterProduct>
+    internal class HandleRegisterProduct: ICommandHandler<RegisterProduct>
     {
         private readonly Func<Product, CancellationToken, ValueTask> addProduct;
         private readonly Func<SKU, CancellationToken, ValueTask<bool>> productWithSKUExists;
@@ -20,47 +22,51 @@ Func<SKU, CancellationToken, ValueTask<bool>> productWithSKUExists
             this.productWithSKUExists = productWithSKUExists;
         }
 
-        public async ValueTask Handle(RegisterProduct command, CancellationToken ct)
+        public async ValueTask<CommandResult> Handle(RegisterProduct command, CancellationToken ct)
         {
+            var productId = Guid.NewGuid();
+            var (skuValue, name, description) = command;
+
+            var sku = SKU.Create(skuValue);
+
             var product = new Product(
-                command.ProductId,
-                command.SKU,
-                command.Name,
-                command.Description
+                productId,
+                sku,
+                name,
+                description
             );
 
-            if (await productWithSKUExists(command.SKU, ct))
+            if (await productWithSKUExists(sku, ct))
                 throw new InvalidOperationException(
-                    $"Product with SKU `{command.SKU} already exists.");
+                    $"Product with SKU `{command.Sku} already exists.");
 
             await addProduct(product, ct);
+
+            return CommandResult.Of(productId);
         }
     }
 
     public record RegisterProduct
     {
-        public Guid ProductId { get;}
-
-        public SKU SKU { get; }
+        public string Sku { get; }
 
         public string Name { get; }
 
         public string? Description { get; }
 
-        private RegisterProduct(Guid productId, SKU sku, string name, string? description)
+        [JsonConstructor]
+        public RegisterProduct(string? sku, string? name, string? description)
         {
-            ProductId = productId;
-            SKU = sku;
-            Name = name;
+            Sku = sku.AssertNotEmpty();
+            Name = name.AssertNotEmpty();
             Description = description;
         }
 
-        public static RegisterProduct Create(Guid? id, string? sku, string? name, string? description)
+        public void Deconstruct(out string sku, out string name, out string? description)
         {
-            if (!id.HasValue) throw new ArgumentNullException(nameof(id));
-            if (name == null) throw new ArgumentNullException(nameof(name));
-
-            return new RegisterProduct(id.Value, SKU.Create(sku), name, description);
+            sku = Sku;
+            name = Name;
+            description = Description;
         }
     }
 }