Ability to limit the scope of Before/After methods on combo handler/http endpoints. Closes GH-1601

Author: jeremydmiller

docs/guide/http/endpoints.md

@@ -336,5 +336,34 @@ public static string GetNow(DateTimeOffset now) // using the custom parameter st
 <sup><a href='https://github.com/JasperFx/wolverine/blob/main/src/Http/WolverineWebApi/CustomParameterEndpoint.cs#L7-L15' title='Snippet source file'>snippet source</a> | <a href='#snippet-sample_http_endpoint_receiving_now' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
+## Http Endpoint / Message Handler Combo
+
+Here's a common scenario that has come up from Wolverine users. Let's say that you have some kind of logical command message that 
+your system needs to handle that might come in from the outside from either HTTP clients or from asynchronous messaging. 
+Folks have frequently asked about how to reuse code between the message handling invocation and the HTTP endpoint. You've
+got a handful of options:
+
+1. Build a message handler and have the HTTP endpoint just delegate to `IMessageBus.InvokeAsync()` with the message
+2. Have both the message handler and HTTP endpoint delegate to shared code, whether that be a shared service, just a static method somewhere, or even
+   have the HTTP endpoint code directly call the concrete message handler
+3. Use a hybrid Message Handler / HTTP Endpoint because Wolverine can do that!
+
+To make a single class and method be both a message handler and HTTP endpoint, just add a `[Wolverine{HttpVerb}]` attribute
+with the route directly on your message handler. As long as that method follows Wolverine's normal naming rules for message
+discovery, Wolverine will treat it as both a message handler and as an HTTP endpoint. Here's an example from our tests:
+
+snippet: sample_using_problem_details_in_message_handler
+
+If you are using Wolverine.HTTP in your application, Wolverine is able to treat `ProblemDetails` similar to the built in
+`HandlerContinuation` when running inside of message handlers.
+
+If you have some middleware methods that should only apply specifically when running as a handler or when running as an HTTP endpoint,
+you can utilize `MiddlewareScoping` directives with `[WolverineBefore]`, `[WolverineAfter]`, or `[WolverineFinally]` attributes to 
+limit the applicability of individual middleware methods. 
+
+::: info
+There is no runtime filtering here because the `MiddlewareScoping` impacts the generated code around your hybrid message handler / 
+HTTP endpoint method, and Wolverine already generates code separately for the two use cases. 
+:::
 
 

src/Http/Wolverine.Http.Tests/combo_handler_and_endpoint.cs

@@ -14,29 +14,42 @@ public combo_handler_and_endpoint(AppFixture fixture) : base(fixture)
     [Fact]
     public async Task use_combo_with_problem_details_as_endpoint()
     {
+        // cleaning up expected change
+        NumberMessageHandler.CalledBeforeOnlyOnHttpEndpoints = false;
+        NumberMessageHandler.CalledBeforeOnlyOnMessageHandlers = false;
+        
         // Should be good
         await Host.Scenario(x =>
         {
-            x.Post.Json(new WolverineWebApi.NumberMessage(3)).ToUrl("/problems");
+            x.Post.Json(new WolverineWebApi.NumberMessage(3)).ToUrl("/problems2");
+            x.StatusCodeShouldBe(204);
         });
 
+        NumberMessageHandler.CalledBeforeOnlyOnHttpEndpoints.ShouldBeTrue();
+        NumberMessageHandler.CalledBeforeOnlyOnMessageHandlers.ShouldBeFalse();
+        
         // should return problem details because the number > 5
         // Should be good
         var result = await Host.Scenario(x =>
         {
-            x.Post.Json(new WolverineWebApi.NumberMessage(10)).ToUrl("/problems");
+            x.Post.Json(new WolverineWebApi.NumberMessage(10)).ToUrl("/problems2");
             x.ContentTypeShouldBe("application/problem+json");
             x.StatusCodeShouldBe(400);
         });
 
         var details = result.ReadAsJson<ProblemDetails>();
 
         details.Detail.ShouldBe("Number is bigger than 5");
+        
+
     }
 
     [Fact]
     public async Task use_combo_as_handler_see_problem_details_catch()
     {
+        // cleaning up expected change
+        NumberMessageHandler.CalledBeforeOnlyOnHttpEndpoints = false;
+        NumberMessageHandler.CalledBeforeOnlyOnMessageHandlers = false;
         NumberMessageHandler.Handled = false;
 
         // This should be invalid and stop
@@ -46,5 +59,8 @@ public async Task use_combo_as_handler_see_problem_details_catch()
         // should be good because we're < 5
         await Host.InvokeAsync(new NumberMessage(3));
         NumberMessageHandler.Handled.ShouldBeTrue();
+        
+        NumberMessageHandler.CalledBeforeOnlyOnHttpEndpoints.ShouldBeFalse();
+        NumberMessageHandler.CalledBeforeOnlyOnMessageHandlers.ShouldBeTrue();
     }
 }

src/Http/WolverineWebApi/ProblemDetailsUsage.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using Microsoft.AspNetCore.Mvc;
+using Wolverine.Attributes;
 using Wolverine.Http;
 
 namespace WolverineWebApi;
@@ -34,10 +35,10 @@ public record NumberMessage(int Number);
 
 #endregion
 
+#region sample_using_problem_details_in_message_handler
+
 public static class NumberMessageHandler
 {
-    #region sample_using_problem_details_in_message_handler
-
     public static ProblemDetails Validate(NumberMessage message)
     {
         if (message.Number > 5)
@@ -52,7 +53,24 @@ public static ProblemDetails Validate(NumberMessage message)
         // All good, keep on going!
         return WolverineContinue.NoProblems;
     }
-    
+
+    // This "Before" method would only be utilized as
+    // an HTTP endpoint
+    [WolverineBefore(MiddlewareScoping.HttpEndpoints)]
+    public static void BeforeButOnlyOnHttp(HttpContext context)
+    {
+        Debug.WriteLine("Got an HTTP request for " + context.TraceIdentifier);
+        CalledBeforeOnlyOnHttpEndpoints = true;
+    }
+
+    // This "Before" method would only be utilized as
+    // a message handler
+    [WolverineBefore(MiddlewareScoping.MessageHandlers)]
+    public static void BeforeButOnlyOnMessageHandlers()
+    {
+        CalledBeforeOnlyOnMessageHandlers = true;
+    }
+
     // Look at this! You can use this as an HTTP endpoint too!
     [WolverinePost("/problems2")]
     public static void Handle(NumberMessage message)
@@ -61,7 +79,10 @@ public static void Handle(NumberMessage message)
         Handled = true;
     }
 
-    #endregion
 
+    // These properties are just a cheap trick in Wolverine internal tests
     public static bool Handled { get; set; }
-}
+    public static bool CalledBeforeOnlyOnMessageHandlers { get; set; }
+    public static bool CalledBeforeOnlyOnHttpEndpoints { get; set; }
+}
+#endregion

src/Wolverine/Attributes/MiddlewareAttribute.cs

@@ -17,9 +17,15 @@ public MiddlewareAttribute(params Type[] frameTypes)
         _frameTypes = frameTypes;
     }
 
+    /// <summary>
+    /// Use this to optionally restrict the application of this middleware to only message handlers
+    /// or HTTP endpoints. Default is Anywhere
+    /// </summary>
+    public MiddlewareScoping Scoping { get; set; } = MiddlewareScoping.Anywhere;
+
     public override void Modify(IChain chain, GenerationRules rules, IServiceContainer container)
     {
-        var applications = _frameTypes.Select(type => new MiddlewarePolicy.Application(type, _ => true)).ToList();
+        var applications = _frameTypes.Select(type => new MiddlewarePolicy.Application(chain, type, _ => true)).ToList();
         MiddlewarePolicy.ApplyToChain(applications, rules, chain);
     }
 }

src/Wolverine/Configuration/Chain.cs

@@ -274,7 +274,7 @@ public void ApplyImpliedMiddlewareFromHandlers(GenerationRules generationRules)
         var handlerTypes = HandlerCalls().Select(x => x.HandlerType).Distinct();
         foreach (var handlerType in handlerTypes)
         {
-            var befores = MiddlewarePolicy.FilterMethods<WolverineBeforeAttribute>(handlerType.GetMethods(),
+            var befores = MiddlewarePolicy.FilterMethods<WolverineBeforeAttribute>(this, handlerType.GetMethods(),
                 MiddlewarePolicy.BeforeMethodNames);
 
             foreach (var before in befores)
@@ -301,7 +301,7 @@ public void ApplyImpliedMiddlewareFromHandlers(GenerationRules generationRules)
                 }
             }
 
-            var afters = MiddlewarePolicy.FilterMethods<WolverineAfterAttribute>(handlerType.GetMethods(),
+            var afters = MiddlewarePolicy.FilterMethods<WolverineAfterAttribute>(this, handlerType.GetMethods(),
                 MiddlewarePolicy.AfterMethodNames).ToArray();
 
             if (afters.Any())

src/Wolverine/Configuration/IChain.cs

@@ -10,6 +10,24 @@
 
 namespace Wolverine.Configuration;
 
+internal static class ChainExtensions
+{
+    public static bool MatchesScope(this IChain chain, MethodInfo method)
+    {
+        if (chain == null) return true;
+
+        if (method.TryGetAttribute<ScopedMiddlewareAttribute>(out var att))
+        {
+            if (att.Scoping == MiddlewareScoping.Anywhere) return true;
+
+            return att.Scoping == chain.Scoping;
+        }
+
+        // All good if no attribute
+        return true;
+    }
+}
+
 #region sample_IChain
 
 /// <summary>

src/Wolverine/Middleware/MiddlewarePolicy.cs

@@ -74,33 +74,38 @@ internal static void ApplyToChain(List<Application> applications, GenerationRule
     public Application AddType(Type middlewareType, Func<IChain, bool>? filter = null)
     {
         filter ??= _ => true;
-        var application = new Application(middlewareType, filter);
+        var application = new Application(null, middlewareType, filter);
         _applications.Add(application);
         return application;
     }
 
-    public static IEnumerable<MethodInfo> FilterMethods<T>(IEnumerable<MethodInfo> methods, string[] validNames)
-        where T : Attribute
+    public static IEnumerable<MethodInfo> FilterMethods<T>(IChain? chain, IEnumerable<MethodInfo> methods,
+        string[] validNames)
+        where T : ScopedMiddlewareAttribute
     {
+        // MatchesScope watches out for null chain
         return methods
-            .Where(x => !x.HasAttribute<WolverineIgnoreAttribute>())
+            .Where(x => !x.HasAttribute<WolverineIgnoreAttribute>() && chain!.MatchesScope(x))
             .Where(x => validNames.Contains(x.Name) || x.HasAttribute<T>());
     }
 
     public class Application
     {
+        private readonly IChain? _chain;
         private readonly MethodInfo[] _afters;
         private readonly MethodInfo[] _befores;
         private readonly ConstructorInfo? _constructor;
         private readonly MethodInfo[] _finals;
-
-        public Application(Type middlewareType, Func<IChain, bool> filter)
+        
+        public Application(IChain? chain, Type middlewareType, Func<IChain, bool> filter)
         {
             if (!middlewareType.IsPublic && !middlewareType.IsVisible)
             {
                 throw new InvalidWolverineMiddlewareException(middlewareType);
             }
 
+            _chain = chain;
+
             if (!middlewareType.IsStatic())
             {
                 var constructors = middlewareType.GetConstructors();
@@ -115,11 +120,11 @@ public Application(Type middlewareType, Func<IChain, bool> filter)
             MiddlewareType = middlewareType;
             Filter = filter;
 
-            var methods = middlewareType.GetMethods().ToArray();
+            var methods = middlewareType.GetMethods().Where(x => x.DeclaringType != typeof(object)).ToArray();
 
-            _befores = FilterMethods<WolverineBeforeAttribute>(methods, BeforeMethodNames).ToArray();
-            _afters = FilterMethods<WolverineAfterAttribute>(methods, AfterMethodNames).ToArray();
-            _finals = FilterMethods<WolverineFinallyAttribute>(methods, FinallyMethodNames).ToArray();
+            _befores = FilterMethods<WolverineBeforeAttribute>(chain, methods, BeforeMethodNames).ToArray();
+            _afters = FilterMethods<WolverineAfterAttribute>(chain, methods, AfterMethodNames).ToArray();
+            _finals = FilterMethods<WolverineFinallyAttribute>(chain, methods, FinallyMethodNames).ToArray();
 
             if (_befores.Length == 0 &&
                 _afters.Length == 0 &&