contract-less composition over controllers

.github/workflows/ci.yml

@@ -34,6 +34,7 @@ jobs:
           dotnet-version: |
             8.0.x
             9.0.x
+            10.0.x
       - name: Build
         run: dotnet build src --configuration Release
       - name: Tests

context/context.md

@@ -87,7 +87,7 @@ endpoints.MapCompositionHandlers()
   - Groups all registered components by route template (from [HttpGet], [HttpPost], etc.)
   - For each unique route+method combination, creates a CompositionEndpointBuilder
   - If CompositionOverControllers is enabled AND a controller already owns the route,
-    stores those handler types in CompositionOverControllersRoutes instead
+    stores those handler types and their method metadata in CompositionOverControllersRoutes instead
   - Registers endpoints via CompositionEndpointDataSource
 ```
 
@@ -100,10 +100,11 @@ HTTP Request
 Enable request body buffering (allows multiple handlers to read body)
   |
   v
-Model Binding Phase (CompositionEndpointBuilder.BindingArguments)
+Model Binding Phase (ComponentsModelBinder)
   - For each component with [BindModel*] attributes on its Handle/Subscribe method
   - Uses RequestModelBinder (wraps ASP.NET Core's IModelBinderFactory)
   - Results stored in IDictionary<Type, IList<ModelBindingArgument>>
+  - Shared by both composition endpoints and composition over controllers
   |
   v
 Endpoint Filter Pipeline (ASP.NET Core IEndpointFilter chain, cached after first build)
@@ -149,6 +150,7 @@ Controller executes normally and produces a result
 OnResultExecutionAsync fires
   - Matches the route against CompositionOverControllersRoutes
   - If composition handlers exist for this route:
+    -> Performs model binding via ComponentsModelBinder using stored handler metadata
     -> Runs the full composition pipeline (same as above)
     -> Merges the composed view model into:
        - ViewResult.ViewData.Model (MVC)
@@ -158,7 +160,7 @@ OnResultExecutionAsync fires
 Result executes with composed data
 ```
 
-**Limitation:** Model binding arguments are NOT supported in this mode (an explicit `NotSupportedException` is thrown).
+Both contract-based (`ICompositionRequestsHandler`) and contract-less composition handlers are supported in this mode.
 
 ## Composition Events System
 
@@ -212,6 +214,13 @@ public Task Handle(HttpRequest request)
 ### 3. Source-Generated (contract-less handlers)
 Convention: class in `*.CompositionHandlers` namespace, name ends with `CompositionHandler`, method decorated with `[Http*]` attribute, returns `Task`. The source generator creates a wrapper implementing `ICompositionRequestsHandler` with appropriate `BindModel` attributes.
 
+Source generator binding heuristics for method parameters (evaluated in order):
+1. Parameter name matches route template placeholder → `BindFromRoute<T>`
+2. Parameter has explicit `[FromBody]` → `BindFromBody<T>`
+3. Parameter has explicit `[FromForm]` → `BindFromForm<T>`
+4. Parameter has explicit `[FromQuery]` or is a simple type → `BindFromQuery<T>`
+5. Complex type without explicit binding attribute → `Bind<T>` (multi-source, respects property-level attributes like `[FromRoute]`)
+
 ### Binding Attributes
 | Attribute | Binding Source |
 |---|---|
@@ -318,7 +327,8 @@ A convention-based alternative to implementing `ICompositionRequestsHandler`. Ru
 | `ViewModelCompositionOptions.cs` | `ViewModelCompositionOptions` - registration orchestrator |
 | `EndpointsExtensions.cs` | `MapCompositionHandlers()` - endpoint mapping |
 | `CompositionEndpointBuilder.cs` | `Build()` - creates the endpoint request delegate |
-| `CompositionEndpointBuilder.BindingArguments.cs` | `GetAllComponentsArguments()` - model binding |
+| `ComponentsModelBinder.cs` | `BindAll()` - shared model binding for all composition paths |
+| `CompositionEndpointBuilder.BindingArguments.cs` | `GetAllComponentsArguments()` - delegates to `ComponentsModelBinder` |
 | `CompositionEndpointBuilder.CompositionFilters.cs` | Composition filter pipeline builder |
 | `CompositionEndpointBuilder.EndpointFilters.cs` | Endpoint filter pipeline builder (cached) |
 | `CompositionEndpointDataSource.cs` | Custom `EndpointDataSource` implementation |
@@ -360,7 +370,7 @@ A convention-based alternative to implementing `ICompositionRequestsHandler`. Ru
 | File | Purpose |
 |---|---|
 | `CompositionOverControllersActionFilter.cs` | `IAsyncResultFilter` - intercepts controller results |
-| `CompositionOverControllersRoutes.cs` | Registry of routes with composition handlers |
+| `CompositionOverControllersRoutes.cs` | Registry of routes with composition handlers and their method metadata |
 | `CompositionOverControllersOptions.cs` | `IsEnabled`, `UseCaseInsensitiveRouteMatching` |
 
 ### Discovery
@@ -393,5 +403,5 @@ A convention-based alternative to implementing `ICompositionRequestsHandler`. Ru
 - `CompositionHandler.cs:38` - Second 404 shortcut
 - `CompositionHandler.cs:42` - Apply composition filter per-handler, not before whole composition
 - `CompositionEndpointBuilder.cs:121` - Source-generate convention-based filter invocation context
-- `CompositionEndpointBuilder.BindingArguments.cs:31` - Cache RequestModelBinder instance
-- `CompositionEndpointBuilder.BindingArguments.cs:38` - Throw if binding failed
+- `ComponentsModelBinder.cs:33` - Cache RequestModelBinder instance
+- `ComponentsModelBinder.cs:40` - Throw if binding failed

docs/composition-over-controllers.md

@@ -15,4 +15,6 @@ services.AddViewModelComposition(options =>
 
 Once composition over controllers is enabled, ServiceComposer will inject a MVC filter to intercept all controllers invocations. If a route matches a regular controller and a set of composition handlers ServiceComposer will invoke the matching handlers after the controller and before the view is rendered.
 
+Composition over controllers supports both regular composition handlers (classes implementing `ICompositionRequestsHandler`) and [contract-less composition handlers](contract-less-composition-requests-handlers.md), including full model binding support for both.
+
 Composition over controllers can be used as a templating engine leveraging the excellent Razor engine. Optionally, it can be used to add ViewModel Composition support to MVC web application without introducing a separate composition gateway.

docs/contract-less-composition-requests-handlers.md

@@ -35,7 +35,6 @@ The syntax is nonetheless similar to ASP.NET controller actions. At compilation
 ### Known limitations
 
 - Different from classes implementing `ICompositionRequestsHandler`, contract-less composition handlers, at the moment, support only one `Http*` attribute per method;
-- At the moment, contract-less composition handlers cannot be used when using [composition over controllers](composition-over-controllers.md);
 
 ## Source generation
 
@@ -70,7 +69,7 @@ namespace Snippets.Contractless.CompositionHandlers.Generated
             var arguments = ctx.GetArguments(this);
             var p0_id = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "id", BindingSource.Path);
             var p1_c = ModelBindingArgumentExtensions.Argument<String>(arguments, "c", BindingSource.Query);
-            var p2_ct = ModelBindingArgumentExtensions.Argument<ComplexType>(arguments, "ct", BindingSource.Body);
+            var p2_ct = ModelBindingArgumentExtensions.Argument<ComplexType>(arguments, BindingSource.Body);
 
             return userHandler.SampleMethod(p0_id, p1_c, p2_ct);
         }

src/ServiceComposer.AspNetCore.SourceGeneration.Tests/ApprovedFiles/AHandlerWithANestedClassCompositionHandler.cs.net8.0.verified.txt

@@ -27,7 +27,7 @@ namespace ServiceComposer.AspNetCore.SourceGeneration.Tests.TestFiles.Compositio
             var arguments = ctx.GetArguments(this);
             var p0_id = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "id", BindingSource.Path);
             var p1_x = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "x", BindingSource.Query);
-            var p2_body = ModelBindingArgumentExtensions.Argument<AHandlerWithANestedClassCompositionHandler.BodyClass>(arguments, "body", BindingSource.Body);
+            var p2_body = ModelBindingArgumentExtensions.Argument<AHandlerWithANestedClassCompositionHandler.BodyClass>(arguments, BindingSource.Body);
 
             return userHandler.Post(p0_id, p1_x, p2_body);
         }

src/ServiceComposer.AspNetCore.SourceGeneration.Tests/ApprovedFiles/AHandlerWithANestedClassCompositionHandler.cs.net9.0.verified.txt

@@ -27,7 +27,7 @@ namespace ServiceComposer.AspNetCore.SourceGeneration.Tests.TestFiles.Compositio
             var arguments = ctx.GetArguments(this);
             var p0_id = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "id", BindingSource.Path);
             var p1_x = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "x", BindingSource.Query);
-            var p2_body = ModelBindingArgumentExtensions.Argument<AHandlerWithANestedClassCompositionHandler.BodyClass>(arguments, "body", BindingSource.Body);
+            var p2_body = ModelBindingArgumentExtensions.Argument<AHandlerWithANestedClassCompositionHandler.BodyClass>(arguments, BindingSource.Body);
 
             return userHandler.Post(p0_id, p1_x, p2_body);
         }

src/ServiceComposer.AspNetCore.SourceGeneration.Tests/ApprovedFiles/WithQueryBindingWithoutAttributeCompositionHandler.cs.net8.0.verified.txt

@@ -28,7 +28,7 @@ namespace ServiceComposer.AspNetCore.SourceGeneration.Tests.TestFiles.Compositio
             var p0_v = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "v", BindingSource.Path);
             var p1_c = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "c", BindingSource.Query);
             var p2_v = ModelBindingArgumentExtensions.Argument<String>(arguments, "v", BindingSource.Query);
-            var p3_body = ModelBindingArgumentExtensions.Argument<WithQueryBindingWithoutAttributeBodyClass>(arguments, "body", BindingSource.Body);
+            var p3_body = ModelBindingArgumentExtensions.Argument<WithQueryBindingWithoutAttributeBodyClass>(arguments, BindingSource.Body);
 
             return userHandler.Post(p0_v, p1_c, p2_v, p3_body);
         }

src/ServiceComposer.AspNetCore.SourceGeneration.Tests/ApprovedFiles/WithQueryBindingWithoutAttributeCompositionHandler.cs.net9.0.verified.txt

@@ -28,7 +28,7 @@ namespace ServiceComposer.AspNetCore.SourceGeneration.Tests.TestFiles.Compositio
             var p0_v = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "v", BindingSource.Path);
             var p1_c = ModelBindingArgumentExtensions.Argument<Int32>(arguments, "c", BindingSource.Query);
             var p2_v = ModelBindingArgumentExtensions.Argument<String>(arguments, "v", BindingSource.Query);
-            var p3_body = ModelBindingArgumentExtensions.Argument<WithQueryBindingWithoutAttributeBodyClass>(arguments, "body", BindingSource.Body);
+            var p3_body = ModelBindingArgumentExtensions.Argument<WithQueryBindingWithoutAttributeBodyClass>(arguments, BindingSource.Body);
 
             return userHandler.Post(p0_v, p1_c, p2_v, p3_body);
         }

src/ServiceComposer.AspNetCore.SourceGeneration/CompositionHandlerWrapperGenerator.cs

@@ -342,7 +342,14 @@ SeparatedSyntaxList<ParameterSyntax> parameters
             var boundParameter = boundParameters[i];
             var arg = $"p{i}_{boundParameter.parameterName}";
             generatedArgs.Add(arg);
-            builder.AppendLine($"            var {arg} = ModelBindingArgumentExtensions.Argument<{boundParameter.parameterType}>(arguments, \"{boundParameter.parameterName}\", {boundParameter.bindingSource});");
+            if (boundParameter.bindingSource is "BindingSource.Body" or "BindingSource.ModelBinding")
+            {
+                builder.AppendLine($"            var {arg} = ModelBindingArgumentExtensions.Argument<{boundParameter.parameterType}>(arguments, {boundParameter.bindingSource});");
+            }
+            else
+            {
+                builder.AppendLine($"            var {arg} = ModelBindingArgumentExtensions.Argument<{boundParameter.parameterType}>(arguments, \"{boundParameter.parameterName}\", {boundParameter.bindingSource});");
+            }
         }
 
         builder.AppendLine();
@@ -442,8 +449,6 @@ bool TryAppendBindingFromBody(SemanticModel semanticModel, StringBuilder builder
         ParameterSyntax parameter, string _, List<string> requiredNamespaces,
         out (string parameterName, string parameterType, string bindingSource) boundParam)
     {
-        var typeSymbol = semanticModel.GetTypeInfo(parameter.Type!).Type;
-        var isSimpleType = IsSimpleType(typeSymbol!);
         var paramTypeFullName = GetTypeAndNamespaceName(semanticModel, parameter.Type!);
         requiredNamespaces.Add(paramTypeFullName.nmespaceName!);
 
@@ -457,9 +462,8 @@ bool TryAppendBindingFromBody(SemanticModel semanticModel, StringBuilder builder
 
         // TODO can we somehow support the EmptyBodyBehavior?
         var (attribute, _) = GetAttributeAndArgument(parameter, attributeNames, "EmptyBodyBehavior");
-        var addAttribute = attribute is not null || isSimpleType == false;
 
-        if (addAttribute)
+        if (attribute is not null)
         {
             builder.AppendLine($"        [BindFromBody<{paramTypeFullName.typeName}>()]");
             boundParam = (parameter.Identifier.Text, paramTypeFullName.typeName!, bindingSource);
@@ -543,6 +547,28 @@ bool TryAppendBindingFromRoute(SemanticModel semanticModel, StringBuilder builde
         return false;
     }
 
+    bool TryAppendMultiSourceBinding(SemanticModel semanticModel, StringBuilder builder,
+        ParameterSyntax parameter, List<string> requiredNamespaces,
+        out (string parameterName, string parameterType, string bindingSource) boundParam)
+    {
+        var typeSymbol = semanticModel.GetTypeInfo(parameter.Type!).Type;
+        var isSimpleType = IsSimpleType(typeSymbol!);
+
+        if (!isSimpleType)
+        {
+            var paramTypeFullName = GetTypeAndNamespaceName(semanticModel, parameter.Type!);
+            requiredNamespaces.Add(paramTypeFullName.nmespaceName!);
+
+            const string bindingSource = "BindingSource.ModelBinding";
+            builder.AppendLine($"        [Bind<{paramTypeFullName.typeName}>()]");
+            boundParam = (parameter.Identifier.Text, paramTypeFullName.typeName!, bindingSource);
+            return true;
+        }
+
+        boundParam = ("", "", "");
+        return false;
+    }
+
     static (AttributeSyntax? attribute, AttributeArgumentSyntax? argument) GetAttributeAndArgument(
         ParameterSyntax parameter, string[] attributeNamesToMatch, string argumentName)
     {
@@ -600,6 +626,12 @@ bool TryAppendBindingFromRoute(SemanticModel semanticModel, StringBuilder builde
                 boundParameters.Add(fromQueryBoundParam);
                 continue;
             }
+
+            if (TryAppendMultiSourceBinding(semanticModel, builder, param, requiredNamespaces,
+                    out var multiSourceBoundParam))
+            {
+                boundParameters.Add(multiSourceBoundParam);
+            }
         }
 
         return boundParameters;