"Required" entity loading in HTTP mechanics Closes GH-470

src/Http/Wolverine.Http.Tests/todo_endpoint_specs.cs

@@ -30,4 +30,14 @@ await Scenario(opts =>
         changes.IsComplete.ShouldBeTrue();
         changes.Name.ShouldBe("Second");
     }
+
+    [Fact]
+    public async Task get_an_automatic_404_when_related_entity_does_not_exist()
+    {
+        await Scenario(opts =>
+        {
+            opts.Put.Json(new UpdateRequest("Second", true)).ToUrl("/todos/1222222222");
+            opts.StatusCodeShouldBe(404);
+        });
+    }
 }

src/Http/Wolverine.Http/Policies/RequiredEntityPolicy.cs

@@ -0,0 +1,75 @@
+using System.ComponentModel.DataAnnotations;
+using JasperFx.CodeGeneration;
+using JasperFx.CodeGeneration.Frames;
+using JasperFx.CodeGeneration.Model;
+using JasperFx.Core.Reflection;
+using Lamar;
+using Microsoft.AspNetCore.Http;
+
+namespace Wolverine.Http.Policies;
+
+internal class RequiredEntityPolicy : IHttpPolicy
+{
+    public void Apply(IReadOnlyList<HttpChain> chains, GenerationRules rules, IContainer container)
+    {
+        foreach (var chain in chains)
+        {
+            if (chain.RoutePattern.Parameters.Any())
+            {
+                var requiredParameters = chain.Method.Method.GetParameters()
+                    .Where(x => x.HasAttribute<RequiredAttribute>() && x.ParameterType.IsClass).ToArray();
+
+                if (requiredParameters.Any())
+                {
+                    chain.Metadata.Produces(404);
+
+                    foreach (var parameter in requiredParameters)
+                    {
+                        var frame = new SetStatusCodeAndReturnFrame(parameter.ParameterType);
+                        chain.Middleware.Add(frame);
+                    }
+                }
+            }
+        }
+    }
+}
+
+internal class SetStatusCodeAndReturnFrame : SyncFrame
+{
+    private readonly Type _entityType;
+    private Variable _httpResponse;
+    private Variable _entity;
+
+    public SetStatusCodeAndReturnFrame(Type entityType)
+    {
+        _entityType = entityType;
+    }
+
+    public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.WriteComment("404 if this required object is null");
+        writer.Write($"BLOCK:if ({_entity.Usage} == null)");
+        writer.Write($"{_httpResponse.Usage}.{nameof(HttpResponse.StatusCode)} = 404;");
+        if (method.AsyncMode == AsyncMode.ReturnCompletedTask)
+        {
+            writer.Write($"return {typeof(Task).FullNameInCode()}.{nameof(Task.CompletedTask)};");
+        }
+        else
+        {
+            writer.Write("return;");
+        }
+
+        writer.FinishBlock();
+
+        Next?.GenerateCode(method, writer);
+    }
+
+    public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
+    {
+        _entity = chain.FindVariable(_entityType);
+        yield return _entity;
+
+        _httpResponse = chain.FindVariable(typeof(HttpResponse));
+        yield return _httpResponse;
+    }
+}

src/Http/Wolverine.Http/WolverineHttpOptions.cs

@@ -4,6 +4,7 @@
 using Lamar;
 using Wolverine.Configuration;
 using Wolverine.Http.CodeGen;
+using Wolverine.Http.Policies;
 using Wolverine.Http.Runtime;
 using Wolverine.Middleware;
 
@@ -16,6 +17,7 @@ public WolverineHttpOptions()
     {
         Policies.Add(new HttpAwarePolicy());
         Policies.Add(new RequestIdPolicy());
+        Policies.Add(new RequiredEntityPolicy());
     }
 
     internal JsonSerializerOptions JsonSerializerOptions { get; set; } = new();

src/Http/WolverineWebApi/Internal/Generated/WolverineHandlers/PUT_todos_id.cs

@@ -0,0 +1,64 @@
+// <auto-generated/>
+#pragma warning disable
+using Marten;
+using Microsoft.AspNetCore.Routing;
+using System;
+using System.Linq;
+using Wolverine.Http;
+
+namespace Internal.Generated.WolverineHandlers
+{
+    // START: PUT_todos_id
+    public class PUT_todos_id : Wolverine.Http.HttpHandler
+    {
+        private readonly Wolverine.Http.WolverineHttpOptions _wolverineHttpOptions;
+        private readonly Marten.ISessionFactory _sessionFactory;
+
+        public PUT_todos_id(Wolverine.Http.WolverineHttpOptions wolverineHttpOptions, Marten.ISessionFactory sessionFactory) : base(wolverineHttpOptions)
+        {
+            _wolverineHttpOptions = wolverineHttpOptions;
+            _sessionFactory = sessionFactory;
+        }
+
+
+
+        public override async System.Threading.Tasks.Task Handle(Microsoft.AspNetCore.Http.HttpContext httpContext)
+        {
+            await using var documentSession = _sessionFactory.OpenSession();
+            if (!int.TryParse((string)httpContext.GetRouteValue("id"), out var id))
+            {
+                httpContext.Response.StatusCode = 404;
+                return;
+            }
+
+
+            var (request, jsonContinue) = await ReadJsonAsync<WolverineWebApi.Samples.UpdateRequest>(httpContext);
+            if (jsonContinue == Wolverine.HandlerContinuation.Stop) return;
+            var todo = await WolverineWebApi.Samples.UpdateEndpoint.LoadAsync(id, documentSession).ConfigureAwait(false);
+            // 404 if this required object is null
+            if (todo == null)
+            {
+                httpContext.Response.StatusCode = 404;
+                return;
+            }
+
+            var storeDoc = WolverineWebApi.Samples.UpdateEndpoint.Put(id, request, todo);
+
+            // Placed by Wolverine's ISideEffect policy
+            storeDoc.Execute(documentSession);
+
+
+            // Commit any outstanding Marten changes
+            await documentSession.SaveChangesAsync(httpContext.RequestAborted).ConfigureAwait(false);
+
+            // Wolverine automatically sets the status code to 204 for empty responses
+            httpContext.Response.StatusCode = 204;
+        }
+
+    }
+
+    // END: PUT_todos_id
+
+
+}
+

src/Http/WolverineWebApi/Samples/TodoController.cs

@@ -1,3 +1,4 @@
+using System.ComponentModel.DataAnnotations;
 using Marten;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -127,7 +128,7 @@ public static class UpdateEndpoint
         => session.LoadAsync<Todo>(id);
 
     [WolverinePut("/todos/{id:int}"), EmptyResponse]
-    public static StoreDoc<Todo> Put(int id, UpdateRequest request, Todo todo)
+    public static StoreDoc<Todo> Put(int id, UpdateRequest request, [Required] Todo? todo)
     {
         todo.Name = request.Name;
         todo.IsComplete = request.IsComplete;