Surrogate argument list in Minimal APIs

src/Http/Http.Abstractions/src/AsParametersAttribute.cs

@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Http;
+
+using System;
+
+/// <summary>
+/// Specifies that a route handler delegate's parameter represents a structured parameter list.
+/// </summary>
+[AttributeUsage(
+    AttributeTargets.Parameter,
+    Inherited = false,
+    AllowMultiple = false)]
+public sealed class AsParametersAttribute : Attribute
+{
+}

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

@@ -3,6 +3,8 @@
 *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.Http.AsParametersAttribute
+Microsoft.AspNetCore.Http.AsParametersAttribute.AsParametersAttribute() -> void
 Microsoft.AspNetCore.Http.DefaultRouteHandlerInvocationContext
 Microsoft.AspNetCore.Http.DefaultRouteHandlerInvocationContext.DefaultRouteHandlerInvocationContext(Microsoft.AspNetCore.Http.HttpContext! httpContext, params object![]! arguments) -> void
 Microsoft.AspNetCore.Http.EndpointMetadataCollection.Enumerator.Current.get -> object!

src/Http/Http.Extensions/src/Microsoft.AspNetCore.Http.Extensions.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <Description>ASP.NET Core common extension methods for HTTP abstractions, HTTP headers, HTTP request/response, and session state.</Description>
@@ -13,6 +13,7 @@
   <ItemGroup>
     <Compile Include="$(SharedSourceRoot)ObjectMethodExecutor\**\*.cs" LinkBase="Shared"/>
     <Compile Include="$(SharedSourceRoot)ParameterBindingMethodCache.cs" LinkBase="Shared"/>
+    <Compile Include="$(SharedSourceRoot)PropertyAsParameterInfo.cs" LinkBase="Shared"/>
     <Compile Include="..\..\Shared\StreamCopyOperationInternal.cs" LinkBase="Shared" />
     <Compile Include="$(SharedSourceRoot)ProblemDetailsJsonConverter.cs" LinkBase="Shared"/>
     <Compile Include="$(SharedSourceRoot)HttpValidationProblemDetailsJsonConverter.cs" LinkBase="Shared" />

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

@@ -9,6 +9,7 @@
 using System.Linq.Expressions;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Security.Claims;
 using System.Text;
 using System.Text.Json;
@@ -222,7 +223,10 @@ private static FactoryContext CreateFactoryContext(RequestDelegateFactoryOptions
         factoryContext.MethodCall = CreateMethodCall(methodInfo, targetExpression, arguments);
 
         // Add metadata provided by the delegate return type and parameter types next, this will be more specific than inferred metadata from above
-        AddTypeProvidedMetadata(methodInfo, factoryContext.Metadata, factoryContext.ServiceProvider);
+        AddTypeProvidedMetadata(methodInfo,
+            factoryContext.Metadata,
+            factoryContext.ServiceProvider,
+            CollectionsMarshal.AsSpan(factoryContext.PropertiesAsParameter));
 
         // Add method attributes as metadata *after* any inferred metadata so that the attributes hava a higher specificity
         AddMethodAttributesAsMetadata(methodInfo, factoryContext.Metadata);
@@ -424,33 +428,40 @@ private static Expression CreateRouteHandlerInvocationContextBase(FactoryContext
         return fallbackConstruction;
     }
 
-    private static void AddTypeProvidedMetadata(MethodInfo methodInfo, List<object> metadata, IServiceProvider? services)
+    private static void AddTypeProvidedMetadata(MethodInfo methodInfo, List<object> metadata, IServiceProvider? services, Span<ParameterInfo> propertiesAsParameter)
     {
         object?[]? invokeArgs = null;
 
-        // Get metadata from parameter types
-        var parameters = methodInfo.GetParameters();
-        foreach (var parameter in parameters)
+        static void AddMetadata(ReadOnlySpan<ParameterInfo> parameters, MethodInfo methodInfo, List<object> metadata, IServiceProvider? services, object?[]? invokeArgs)
         {
-            if (typeof(IEndpointParameterMetadataProvider).IsAssignableFrom(parameter.ParameterType))
+            foreach (var parameter in parameters)
             {
-                // Parameter type implements IEndpointParameterMetadataProvider
-                var parameterContext = new EndpointParameterMetadataContext(parameter, metadata, services);
-                invokeArgs ??= new object[1];
-                invokeArgs[0] = parameterContext;
-                PopulateMetadataForParameterMethod.MakeGenericMethod(parameter.ParameterType).Invoke(null, invokeArgs);
-            }
+                if (typeof(IEndpointParameterMetadataProvider).IsAssignableFrom(parameter.ParameterType))
+                {
+                    // Parameter type implements IEndpointParameterMetadataProvider
+                    var parameterContext = new EndpointParameterMetadataContext(parameter, metadata, services);
+                    invokeArgs ??= new object[1];
+                    invokeArgs[0] = parameterContext;
+                    PopulateMetadataForParameterMethod.MakeGenericMethod(parameter.ParameterType).Invoke(null, invokeArgs);
+                }
 
-            if (typeof(IEndpointMetadataProvider).IsAssignableFrom(parameter.ParameterType))
-            {
-                // Parameter type implements IEndpointMetadataProvider
-                var context = new EndpointMetadataContext(methodInfo, metadata, services);
-                invokeArgs ??= new object[1];
-                invokeArgs[0] = context;
-                PopulateMetadataForEndpointMethod.MakeGenericMethod(parameter.ParameterType).Invoke(null, invokeArgs);
+                if (typeof(IEndpointMetadataProvider).IsAssignableFrom(parameter.ParameterType))
+                {
+                    // Parameter type implements IEndpointMetadataProvider
+                    var context = new EndpointMetadataContext(methodInfo, metadata, services);
+                    invokeArgs ??= new object[1];
+                    invokeArgs[0] = context;
+                    PopulateMetadataForEndpointMethod.MakeGenericMethod(parameter.ParameterType).Invoke(null, invokeArgs);
+                }
             }
         }
 
+        // Get metadata from parameter types
+        AddMetadata(methodInfo.GetParameters(), methodInfo, metadata, services, invokeArgs);
+
+        // Get metadata from properties as parameter types
+        AddMetadata(propertiesAsParameter, methodInfo, metadata, services, invokeArgs);
+
         // Get metadata from return type
         var returnType = methodInfo.ReturnType;
         if (AwaitableInfo.IsTypeAwaitable(returnType, out var awaitableInfo))
@@ -507,6 +518,7 @@ private static Expression[] CreateArguments(ParameterInfo[]? parameters, Factory
         for (var i = 0; i < parameters.Length; i++)
         {
             args[i] = CreateArgument(parameters[i], factoryContext);
+
             // Register expressions containing the boxed and unboxed variants
             // of the route handler's arguments for use in RouteHandlerInvocationContext
             // construction and route handler invocation.
@@ -635,6 +647,16 @@ private static Expression CreateArgument(ParameterInfo parameter, FactoryContext
         {
             return RequestPipeReaderExpr;
         }
+        else if (parameter.CustomAttributes.Any(a => typeof(AsParametersAttribute).IsAssignableFrom(a.AttributeType)))
+        {
+            if (parameter is PropertyAsParameterInfo)
+            {
+                throw new NotSupportedException(
+                    $"Nested {nameof(AsParametersAttribute)} is not supported and should be used only for handler parameters.");
+            }
+
+            return BindParameterFromProperties(parameter, factoryContext);
+        }
         else if (ParameterBindingMethodCache.HasBindAsyncMethod(parameter))
         {
             return BindParameterFromBindAsync(parameter, factoryContext);
@@ -1221,6 +1243,68 @@ private static Expression GetValueFromProperty(Expression sourceExpression, stri
         return Expression.Convert(indexExpression, returnType ?? typeof(string));
     }
 
+    private static Expression BindParameterFromProperties(ParameterInfo parameter, FactoryContext factoryContext)
+    {
+        var argumentExpression = Expression.Variable(parameter.ParameterType, $"{parameter.Name}_local");
+        var (constructor, parameters) = ParameterBindingMethodCache.FindConstructor(parameter.ParameterType);
+
+        if (constructor is not null && parameters is { Length: > 0 })
+        {
+            //  arg_local = new T(....)
+
+            var constructorArguments = new Expression[parameters.Length];
+
+            for (var i = 0; i < parameters.Length; i++)
+            {
+                var parameterInfo =
+                    new PropertyAsParameterInfo(parameters[i].PropertyInfo, parameters[i].ParameterInfo, factoryContext.NullabilityContext);
+                constructorArguments[i] = CreateArgument(parameterInfo, factoryContext);
+                factoryContext.PropertiesAsParameter.Add(parameterInfo);
+            }
+
+            factoryContext.ParamCheckExpressions.Add(
+                Expression.Assign(
+                    argumentExpression,
+                    Expression.New(constructor, constructorArguments)));
+        }
+        else
+        {
+            //  arg_local = new T()
+            //  {
+            //      arg_local.Property[0] = expression[0],
+            //      arg_local.Property[n] = expression[n],
+            //  }
+
+            var properties = parameter.ParameterType.GetProperties();
+            var bindings = new List<MemberBinding>(properties.Length);
+
+            for (var i = 0; i < properties.Length; i++)
+            {
+                // For parameterless ctor we will init only writable properties.
+                if (properties[i].CanWrite)
+                {
+                    var parameterInfo = new PropertyAsParameterInfo(properties[i], factoryContext.NullabilityContext);
+                    bindings.Add(Expression.Bind(properties[i], CreateArgument(parameterInfo, factoryContext)));
+                    factoryContext.PropertiesAsParameter.Add(parameterInfo);
+                }
+            }
+
+            var newExpression = constructor is null ?
+                Expression.New(parameter.ParameterType) :
+                Expression.New(constructor);
+
+            factoryContext.ParamCheckExpressions.Add(
+                Expression.Assign(
+                    argumentExpression,
+                    Expression.MemberInit(newExpression, bindings)));
+        }
+
+        factoryContext.TrackedParameters.Add(parameter.Name!, RequestDelegateFactoryConstants.PropertyAsParameter);
+        factoryContext.ExtraLocals.Add(argumentExpression);
+
+        return argumentExpression;
+    }
+
     private static Expression BindParameterFromService(ParameterInfo parameter, FactoryContext factoryContext)
     {
         var isOptional = IsOptionalParameter(parameter, factoryContext);
@@ -1711,15 +1795,20 @@ private static Expression BindParameterFromBody(ParameterInfo parameter, bool al
 
     private static bool IsOptionalParameter(ParameterInfo parameter, FactoryContext factoryContext)
     {
+        if (parameter is PropertyAsParameterInfo argument)
+        {
+            return argument.IsOptional;
+        }
+
         // - Parameters representing value or reference types with a default value
         // under any nullability context are treated as optional.
         // - Value type parameters without a default value in an oblivious
         // nullability context are required.
         // - Reference type parameters without a default value in an oblivious
         // nullability context are optional.
-        var nullability = factoryContext.NullabilityContext.Create(parameter);
+        var nullabilityInfo = factoryContext.NullabilityContext.Create(parameter);
         return parameter.HasDefaultValue
-            || nullability.ReadState != NullabilityState.NotNull;
+            || nullabilityInfo.ReadState != NullabilityState.NotNull;
     }
 
     private static MethodInfo GetMethodInfo<T>(Expression<T> expr)
@@ -2000,9 +2089,11 @@ private sealed class FactoryContext
         public List<Expression> ContextArgAccess { get; } = new();
         public Expression? MethodCall { get; set; }
         public Type[] ArgumentTypes { get; set; } = Array.Empty<Type>();
-        public Expression[] ArgumentExpressions { get; set;  } = Array.Empty<Expression>();
+        public Expression[] ArgumentExpressions { get; set; } = Array.Empty<Expression>();
         public Expression[] BoxedArgs { get; set;  } = Array.Empty<Expression>();
         public List<Func<RouteHandlerContext, RouteHandlerFilterDelegate, RouteHandlerFilterDelegate>>? Filters { get; init; }
+
+        public List<ParameterInfo> PropertiesAsParameter { get; } = new();
     }
 
     private static class RequestDelegateFactoryConstants
@@ -2019,6 +2110,7 @@ private static class RequestDelegateFactoryConstants
         public const string BodyParameter = "Body (Inferred)";
         public const string RouteOrQueryStringParameter = "Route or Query String (Inferred)";
         public const string FormFileParameter = "Form File (Inferred)";
+        public const string PropertyAsParameter = "As Parameter (Attribute)";
     }
 
     private static partial class Log