[Route Groups] Support AddFilter, WithOpenApi and other additive conventions

src/DefaultBuilder/test/Microsoft.AspNetCore.Tests/WebApplicationTests.cs

@@ -1572,12 +1572,13 @@ public async Task BranchingPipelineHasOwnRoutes()
         app.Start();
 
         var ds = app.Services.GetRequiredService<EndpointDataSource>();
-        Assert.Equal(5, ds.Endpoints.Count);
-        Assert.Equal("One", ds.Endpoints[0].DisplayName);
-        Assert.Equal("Two", ds.Endpoints[1].DisplayName);
-        Assert.Equal("Three", ds.Endpoints[2].DisplayName);
-        Assert.Equal("Four", ds.Endpoints[3].DisplayName);
-        Assert.Equal("Five", ds.Endpoints[4].DisplayName);
+        var displayNames = ds.Endpoints.Select(e => e.DisplayName).ToArray();
+        Assert.Equal(5, displayNames.Length);
+        Assert.Contains("One", displayNames);
+        Assert.Contains("Two", displayNames);
+        Assert.Contains("Three", displayNames);
+        Assert.Contains("Four", displayNames);
+        Assert.Contains("Five", displayNames);
 
         var client = app.GetTestClient();
 

src/Http/Http.Abstractions/src/Extensions/EndpointBuilder.cs

@@ -28,11 +28,17 @@ public abstract class EndpointBuilder
     /// <summary>
     /// Gets the <see cref="IServiceProvider"/> associated with the endpoint.
     /// </summary>
-    public IServiceProvider? ServiceProvider { get; set; }
+    public IServiceProvider ApplicationServices { get; set; } = EmptyServiceProvicer.Instance;
 
     /// <summary>
     /// Creates an instance of <see cref="Endpoint"/> from the <see cref="EndpointBuilder"/>.
     /// </summary>
     /// <returns>The created <see cref="Endpoint"/>.</returns>
     public abstract Endpoint Build();
+
+    private sealed class EmptyServiceProvicer : IServiceProvider
+    {
+        public static EmptyServiceProvicer Instance { get; } = new EmptyServiceProvicer();
+        public object? GetService(Type serviceType) => null;
+    }
 }

src/Http/Http.Abstractions/src/PublicAPI.Unshipped.txt

@@ -1,8 +1,8 @@
 #nullable enable
 *REMOVED*abstract Microsoft.AspNetCore.Http.HttpResponse.ContentType.get -> string!
 *REMOVED*Microsoft.AspNetCore.Http.EndpointMetadataCollection.Enumerator.Current.get -> object?
-Microsoft.AspNetCore.Builder.EndpointBuilder.ServiceProvider.get -> System.IServiceProvider?
-Microsoft.AspNetCore.Builder.EndpointBuilder.ServiceProvider.set -> void
+Microsoft.AspNetCore.Builder.EndpointBuilder.ApplicationServices.get -> System.IServiceProvider!
+Microsoft.AspNetCore.Builder.EndpointBuilder.ApplicationServices.set -> void
 Microsoft.AspNetCore.Http.AsParametersAttribute
 Microsoft.AspNetCore.Http.AsParametersAttribute.AsParametersAttribute() -> void
 Microsoft.AspNetCore.Http.DefaultRouteHandlerInvocationContext
@@ -18,9 +18,9 @@ Microsoft.AspNetCore.Http.Metadata.IRequestSizeLimitMetadata
 Microsoft.AspNetCore.Http.Metadata.IRequestSizeLimitMetadata.MaxRequestBodySize.get -> long?
 Microsoft.AspNetCore.Http.RouteHandlerContext
 Microsoft.AspNetCore.Http.RouteHandlerContext.ApplicationServices.get -> System.IServiceProvider!
-Microsoft.AspNetCore.Http.RouteHandlerContext.EndpointMetadata.get -> Microsoft.AspNetCore.Http.EndpointMetadataCollection!
+Microsoft.AspNetCore.Http.RouteHandlerContext.EndpointMetadata.get -> System.Collections.Generic.IList<object!>!
 Microsoft.AspNetCore.Http.RouteHandlerContext.MethodInfo.get -> System.Reflection.MethodInfo!
-Microsoft.AspNetCore.Http.RouteHandlerContext.RouteHandlerContext(System.Reflection.MethodInfo! methodInfo, Microsoft.AspNetCore.Http.EndpointMetadataCollection! endpointMetadata, System.IServiceProvider! applicationServices) -> void
+Microsoft.AspNetCore.Http.RouteHandlerContext.RouteHandlerContext(System.Reflection.MethodInfo! methodInfo, System.Collections.Generic.IList<object!>! endpointMetadata, System.IServiceProvider! applicationServices) -> void
 Microsoft.AspNetCore.Http.RouteHandlerFilterDelegate
 Microsoft.AspNetCore.Http.RouteHandlerInvocationContext
 Microsoft.AspNetCore.Http.RouteHandlerInvocationContext.RouteHandlerInvocationContext() -> void

src/Http/Http.Abstractions/src/RequestDelegateResult.cs

@@ -23,7 +23,8 @@ public RequestDelegateResult(RequestDelegate requestDelegate, IReadOnlyList<obje
     public RequestDelegate RequestDelegate { get; }
 
     /// <summary>
-    /// Gets endpoint metadata inferred from creating the <see cref="RequestDelegate" />
+    /// Gets endpoint metadata inferred from creating the <see cref="RequestDelegate" />. If a non-null
+    /// RequestDelegateFactoryOptions.EndpointMetadata list was passed in, this will be the same instance.
     /// </summary>
     public IReadOnlyList<object> EndpointMetadata { get; }
 }

src/Http/Http.Abstractions/src/RouteHandlerContext.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Reflection;
+using Microsoft.AspNetCore.Builder;
 
 namespace Microsoft.AspNetCore.Http;
 
@@ -15,9 +16,9 @@ public sealed class RouteHandlerContext
     /// Creates a new instance of the <see cref="RouteHandlerContext"/>.
     /// </summary>
     /// <param name="methodInfo">The <see cref="MethodInfo"/> associated with the route handler of the current request.</param>
-    /// <param name="endpointMetadata">The <see cref="EndpointMetadataCollection"/> associated with the endpoint the filter is targeting.</param>
+    /// <param name="endpointMetadata">The <see cref="EndpointBuilder.Metadata"/> associated with the endpoint the filter is targeting.</param>
     /// <param name="applicationServices">The <see cref="IServiceProvider"/> instance used to access the application services.</param>
-    public RouteHandlerContext(MethodInfo methodInfo, EndpointMetadataCollection endpointMetadata, IServiceProvider applicationServices)
+    public RouteHandlerContext(MethodInfo methodInfo, IList<object> endpointMetadata, IServiceProvider applicationServices)
     {
         ArgumentNullException.ThrowIfNull(methodInfo);
         ArgumentNullException.ThrowIfNull(endpointMetadata);
@@ -36,7 +37,7 @@ public RouteHandlerContext(MethodInfo methodInfo, EndpointMetadataCollection end
     /// <summary>
     /// The <see cref="EndpointMetadataCollection"/> associated with the current endpoint.
     /// </summary>
-    public EndpointMetadataCollection EndpointMetadata { get; }
+    public IList<object> EndpointMetadata { get; }
 
     /// <summary>
     /// Gets the <see cref="IServiceProvider"/> instance used to access application services.

src/Http/Http.Extensions/src/PublicAPI.Unshipped.txt

@@ -13,8 +13,8 @@ Microsoft.AspNetCore.Http.Metadata.IEndpointMetadataProvider
 Microsoft.AspNetCore.Http.Metadata.IEndpointMetadataProvider.PopulateMetadata(Microsoft.AspNetCore.Http.Metadata.EndpointMetadataContext! context) -> void
 Microsoft.AspNetCore.Http.Metadata.IEndpointParameterMetadataProvider
 Microsoft.AspNetCore.Http.Metadata.IEndpointParameterMetadataProvider.PopulateMetadata(Microsoft.AspNetCore.Http.Metadata.EndpointParameterMetadataContext! parameterContext) -> void
-Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.InitialEndpointMetadata.get -> System.Collections.Generic.IEnumerable<object!>?
-Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.InitialEndpointMetadata.init -> void
+Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.EndpointMetadata.get -> System.Collections.Generic.IList<object!>?
+Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.EndpointMetadata.init -> void
 Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.RouteHandlerFilterFactories.get -> System.Collections.Generic.IReadOnlyList<System.Func<Microsoft.AspNetCore.Http.RouteHandlerContext!, Microsoft.AspNetCore.Http.RouteHandlerFilterDelegate!, Microsoft.AspNetCore.Http.RouteHandlerFilterDelegate!>!>?
 Microsoft.AspNetCore.Http.RequestDelegateFactoryOptions.RouteHandlerFilterFactories.init -> void
 Microsoft.Extensions.DependencyInjection.RouteHandlerJsonServiceExtensions

src/Http/Http.Extensions/src/RequestDelegateFactory.cs

@@ -133,7 +133,7 @@ public static RequestDelegateResult Create(Delegate handler, RequestDelegateFact
 
         var targetableRequestDelegate = CreateTargetableRequestDelegate(handler.Method, targetExpression, factoryContext, targetFactory);
 
-        return new RequestDelegateResult(httpContext => targetableRequestDelegate(handler.Target, httpContext), factoryContext.Metadata);
+        return new RequestDelegateResult(httpContext => targetableRequestDelegate(handler.Target, httpContext), AsReadOnlyList(factoryContext.Metadata));
     }
 
     /// <summary>
@@ -165,7 +165,7 @@ public static RequestDelegateResult Create(MethodInfo methodInfo, Func<HttpConte
             {
                 var untargetableRequestDelegate = CreateTargetableRequestDelegate(methodInfo, targetExpression: null, factoryContext);
 
-                return new RequestDelegateResult(httpContext => untargetableRequestDelegate(null, httpContext), factoryContext.Metadata);
+                return new RequestDelegateResult(httpContext => untargetableRequestDelegate(null, httpContext), AsReadOnlyList(factoryContext.Metadata));
             }
 
             targetFactory = context => Activator.CreateInstance(methodInfo.DeclaringType)!;
@@ -174,27 +174,31 @@ public static RequestDelegateResult Create(MethodInfo methodInfo, Func<HttpConte
         var targetExpression = Expression.Convert(TargetExpr, methodInfo.DeclaringType);
         var targetableRequestDelegate = CreateTargetableRequestDelegate(methodInfo, targetExpression, factoryContext, context => targetFactory(context));
 
-        return new RequestDelegateResult(httpContext => targetableRequestDelegate(targetFactory(httpContext), httpContext), factoryContext.Metadata);
+        return new RequestDelegateResult(httpContext => targetableRequestDelegate(targetFactory(httpContext), httpContext), AsReadOnlyList(factoryContext.Metadata));
     }
 
     private static FactoryContext CreateFactoryContext(RequestDelegateFactoryOptions? options)
     {
-        var context = new FactoryContext
+        return new FactoryContext
         {
             ServiceProvider = options?.ServiceProvider,
             ServiceProviderIsService = options?.ServiceProvider?.GetService<IServiceProviderIsService>(),
             RouteParameters = options?.RouteParameterNames?.ToList(),
             ThrowOnBadRequest = options?.ThrowOnBadRequest ?? false,
             DisableInferredFromBody = options?.DisableInferBodyFromParameters ?? false,
-            Filters = options?.RouteHandlerFilterFactories?.ToList()
+            Filters = options?.RouteHandlerFilterFactories?.ToList(),
+            Metadata = options?.EndpointMetadata ?? new List<object>(),
         };
+    }
 
-        if (options?.InitialEndpointMetadata is not null)
+    private static IReadOnlyList<object> AsReadOnlyList(IList<object> metadata)
+    {
+        if (metadata is IReadOnlyList<object> readOnlyList)
         {
-            context.Metadata.AddRange(options.InitialEndpointMetadata);
+            return readOnlyList;
         }
 
-        return context;
+        return new List<object>(metadata);
     }
 
     private static Func<object?, HttpContext, Task> CreateTargetableRequestDelegate(MethodInfo methodInfo, Expression? targetExpression, FactoryContext factoryContext, Expression<Func<HttpContext, object?>>? targetFactory = null)
@@ -215,9 +219,6 @@ private static FactoryContext CreateFactoryContext(RequestDelegateFactoryOptions
         //     return default;
         // }
 
-        // Add MethodInfo as first metadata item
-        factoryContext.Metadata.Insert(0, methodInfo);
-
         // CreateArguments will add metadata inferred from parameter details
         var arguments = CreateArguments(methodInfo.GetParameters(), factoryContext);
         var returnType = methodInfo.ReturnType;
@@ -229,9 +230,6 @@ private static FactoryContext CreateFactoryContext(RequestDelegateFactoryOptions
             factoryContext.ServiceProvider,
             CollectionsMarshal.AsSpan(factoryContext.Parameters));
 
-        // Add method attributes as metadata *after* any inferred metadata so that the attributes hava a higher specificity
-        AddMethodAttributesAsMetadata(methodInfo, factoryContext.Metadata);
-
         // If there are filters registered on the route handler, then we update the method call and
         // return type associated with the request to allow for the filter invocation pipeline.
         if (factoryContext.Filters is { Count: > 0 })
@@ -305,7 +303,7 @@ targetExpression is null
             FilterContextExpr).Compile();
         var routeHandlerContext = new RouteHandlerContext(
             methodInfo,
-            new EndpointMetadataCollection(factoryContext.Metadata),
+            factoryContext.Metadata,
             factoryContext.ServiceProvider ?? EmptyServiceProvider.Instance);
 
         for (var i = factoryContext.Filters.Count - 1; i >= 0; i--)
@@ -433,7 +431,7 @@ private static Expression CreateRouteHandlerInvocationContextBase(FactoryContext
         return fallbackConstruction;
     }
 
-    private static void AddTypeProvidedMetadata(MethodInfo methodInfo, List<object> metadata, IServiceProvider? services, ReadOnlySpan<ParameterInfo> parameters)
+    private static void AddTypeProvidedMetadata(MethodInfo methodInfo, IList<object> metadata, IServiceProvider? services, ReadOnlySpan<ParameterInfo> parameters)
     {
         object?[]? invokeArgs = null;
 
@@ -488,17 +486,6 @@ private static void PopulateMetadataForEndpoint<T>(EndpointMetadataContext conte
         T.PopulateMetadata(context);
     }
 
-    private static void AddMethodAttributesAsMetadata(MethodInfo methodInfo, List<object> metadata)
-    {
-        var attributes = methodInfo.GetCustomAttributes();
-
-        // This can be null if the delegate is a dynamic method or compiled from an expression tree
-        if (attributes is not null)
-        {
-            metadata.AddRange(attributes);
-        }
-    }
-
     private static Expression[] CreateArguments(ParameterInfo[]? parameters, FactoryContext factoryContext)
     {
         if (parameters is null || parameters.Length == 0)
@@ -1659,6 +1646,14 @@ private static Expression BindParameterFromBindAsync(ParameterInfo parameter, Fa
         return Expression.Convert(boundValueExpr, parameter.ParameterType);
     }
 
+    private static void InsertInferredAcceptsMetadata(FactoryContext factoryContext, Type type, string[] contentTypes)
+    {
+        // Unlike most metadata that will probably to be added by filters or metadata providers, we insert the automatically-inferred AcceptsMetadata
+        // to the beginning of the metadata to give it the lowest precedence. It really doesn't makes sense for this metadata to be overridden but
+        // we're preserving the old behavior here out of an abundance of caution.
+        factoryContext.Metadata.Insert(0, new AcceptsMetadata(type, factoryContext.AllowEmptyRequestBody, contentTypes));
+    }
+
     private static Expression BindParameterFromFormFiles(
         ParameterInfo parameter,
         FactoryContext factoryContext)
@@ -1673,7 +1668,7 @@ private static Expression BindParameterFromFormFiles(
         // Do not duplicate the metadata if there are multiple form parameters
         if (!factoryContext.ReadForm)
         {
-            factoryContext.Metadata.Add(new AcceptsMetadata(parameter.ParameterType, factoryContext.AllowEmptyRequestBody, FormFileContentType));
+            InsertInferredAcceptsMetadata(factoryContext, parameter.ParameterType,  FormFileContentType);
         }
 
         factoryContext.ReadForm = true;
@@ -1697,7 +1692,7 @@ private static Expression BindParameterFromFormFile(
         // Do not duplicate the metadata if there are multiple form parameters
         if (!factoryContext.ReadForm)
         {
-            factoryContext.Metadata.Add(new AcceptsMetadata(parameter.ParameterType, factoryContext.AllowEmptyRequestBody, FormFileContentType));
+            InsertInferredAcceptsMetadata(factoryContext, parameter.ParameterType, FormFileContentType);
         }
 
         factoryContext.ReadForm = true;
@@ -1727,7 +1722,7 @@ private static Expression BindParameterFromBody(ParameterInfo parameter, bool al
 
         factoryContext.JsonRequestBodyParameter = parameter;
         factoryContext.AllowEmptyRequestBody = allowEmpty || isOptional;
-        factoryContext.Metadata.Add(new AcceptsMetadata(parameter.ParameterType, factoryContext.AllowEmptyRequestBody, DefaultAcceptsContentType));
+        InsertInferredAcceptsMetadata(factoryContext, parameter.ParameterType, DefaultAcceptsContentType);
 
         if (!factoryContext.AllowEmptyRequestBody)
         {
@@ -2077,7 +2072,7 @@ private sealed class FactoryContext
         public bool HasMultipleBodyParameters { get; set; }
         public bool HasInferredBody { get; set; }
 
-        public List<object> Metadata { get; internal set; } = new();
+        public IList<object> Metadata { get; init; } = default!;
 
         public NullabilityInfoContext NullabilityContext { get; } = new();
 

src/Http/Http.Extensions/src/RequestDelegateFactoryOptions.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.Extensions.Logging;
 
@@ -38,13 +39,16 @@ public sealed class RequestDelegateFactoryOptions
     public IReadOnlyList<Func<RouteHandlerContext, RouteHandlerFilterDelegate, RouteHandlerFilterDelegate>>? RouteHandlerFilterFactories { get; init; }
 
     /// <summary>
-    /// The initial endpoint metadata to add as part of the creation of the <see cref="RequestDelegateResult.RequestDelegate"/>.
+    /// The mutable initial endpoint metadata to add as part of the creation of the <see cref="RequestDelegateResult.RequestDelegate"/>. In most cases,
+    /// this should come from <see cref="EndpointBuilder.Metadata"/>.
     /// </summary>
     /// <remarks>
-    /// This metadata will be included in <see cref="RequestDelegateResult.EndpointMetadata" /> <b>before</b> any metadata inferred during creation of the
+    /// This metadata will be included in <see cref="RequestDelegateResult.EndpointMetadata" /> <b>before</b> most metadata inferred during creation of the
     /// <see cref="RequestDelegateResult.RequestDelegate"/> and <b>before</b> any metadata provided by types in the delegate signature that implement
-    /// <see cref="IEndpointMetadataProvider" /> or <see cref="IEndpointParameterMetadataProvider" />, i.e. this metadata will be less specific than any
-    /// inferred by the call to <see cref="RequestDelegateFactory.Create(Delegate, RequestDelegateFactoryOptions?)"/>.
+    /// <see cref="IEndpointMetadataProvider" /> or <see cref="IEndpointParameterMetadataProvider" />. The exception to this general rule is the
+    /// <see cref="IAcceptsMetadata"/> that <see cref="RequestDelegateFactory.Create(Delegate, RequestDelegateFactoryOptions?)"/> infers automatically
+    /// without any custom metadata providers which instead is inserted at the start to give it lower precedence. Custom metadata providers can choose to do
+    /// insert their metadata at the start to give lower precedence, but this is unusual.
     /// </remarks>
-    public IEnumerable<object>? InitialEndpointMetadata { get; init; }
+    public IList<object>? EndpointMetadata { get; init; }
 }