Refactor ModelMetadata for trim compatability

src/Mvc/Mvc.Abstractions/src/ModelBinding/ModelMetadata.cs

@@ -9,6 +9,7 @@
 using System.Linq.Expressions;
 using System.Reflection;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
@@ -30,6 +31,17 @@ public abstract class ModelMetadata : IEquatable<ModelMetadata?>, IModelMetadata
     private static readonly ParameterBindingMethodCache ParameterBindingMethodCache
         = new(throwOnInvalidMethod: false);
 
+    /// <summary>
+    /// Exposes a feature switch to disable generating model metadata with reflection-heavy strategies.
+    /// This is primarily intended for use in Minimal API-based scenarios where information is derived from
+    /// IParameterBindingMetadata
+    /// </summary>
+    [FeatureSwitchDefinition("Microsoft.AspNetCore.Mvc.ApiExplorer.IsEnhancedModelMetadataSupported")]
+    [FeatureGuard(typeof(RequiresDynamicCodeAttribute))]
+    [FeatureGuard(typeof(RequiresUnreferencedCodeAttribute))]
+    private static bool IsEnhancedModelMetadataSupported { get; } =
+        AppContext.TryGetSwitch("Microsoft.AspNetCore.Mvc.ApiExplorer.IsEnhancedModelMetadataSupported", out var isEnhancedModelMetadataSupported) ? isEnhancedModelMetadataSupported : true;
+
     private int? _hashCode;
     private IReadOnlyList<ModelMetadata>? _boundProperties;
     private IReadOnlyDictionary<ModelMetadata, ModelMetadata>? _parameterMapping;
@@ -44,8 +56,58 @@ private static readonly ParameterBindingMethodCache ParameterBindingMethodCache
     protected ModelMetadata(ModelMetadataIdentity identity)
     {
         Identity = identity;
+        if (IsEnhancedModelMetadataSupported)
+        {
+            InitializeTypeInformation();
+        }
+    }
+
+    /// <summary>
+    /// Creates a new <see cref="ModelMetadata"/> from a <see cref="IParameterBindingMetadata"/> instance
+    /// and its associated type.
+    /// </summary>
+    /// <param name="type">The <see cref="Type"/> associated with the <see cref="ModelMetadata"/>  generated.</param>
+    /// <param name="parameterBindingMetadata">The <see cref="IParameterBindingMetadata"/> instance associated with the <see cref="ModelMetadata"/> generated.</param>
+    protected ModelMetadata(Type type, IParameterBindingMetadata? parameterBindingMetadata)
+    {
+        Identity = ModelMetadataIdentity.ForType(type);
 
-        InitializeTypeInformation();
+        InitializeTypeInformationFromType();
+        if (parameterBindingMetadata is not null)
+        {
+            InitializeTypeInformationFromParameterBindingMetadata(parameterBindingMetadata);
+        }
+    }
+
+    private void InitializeTypeInformationFromType()
+    {
+        IsNullableValueType = Nullable.GetUnderlyingType(ModelType) != null;
+        IsReferenceOrNullableType = !ModelType.IsValueType || IsNullableValueType;
+        UnderlyingOrModelType = Nullable.GetUnderlyingType(ModelType) ?? ModelType;
+
+        if (ModelType == typeof(string) || !typeof(IEnumerable).IsAssignableFrom(ModelType))
+        {
+            // Do nothing, not Enumerable.
+        }
+        else if (ModelType.IsArray)
+        {
+            IsEnumerableType = true;
+            ElementType = ModelType.GetElementType()!;
+        }
+    }
+
+    private void InitializeTypeInformationFromParameterBindingMetadata(IParameterBindingMetadata parameterBindingMetadata)
+    {
+        // We assume that parameters bound from an endpoint's metadata originated from minimal API's source
+        // generation layer and are not convertible based on the `TypeConverter`s in MVC.
+        IsConvertibleType = false;
+        HasDefaultValue = parameterBindingMetadata.ParameterInfo.HasDefaultValue;
+        IsParseableType = parameterBindingMetadata.HasTryParse;
+        IsComplexType = !IsParseableType;
+
+        var nullabilityContext = new NullabilityInfoContext();
+        var nullability = nullabilityContext.Create(parameterBindingMetadata.ParameterInfo);
+        NullabilityState = nullability?.ReadState ?? NullabilityState.Unknown;
     }
 
     /// <summary>
@@ -442,7 +504,7 @@ internal IReadOnlyDictionary<ModelMetadata, ModelMetadata> BoundConstructorPrope
     /// from <see cref="string"/> and without a <c>TryParse</c> method. Most POCO and <see cref="IEnumerable"/> types are therefore complex.
     /// Most, if not all, BCL value types are simple types.
     /// </remarks>
-    public bool IsComplexType => !IsConvertibleType && !IsParseableType;
+    public bool IsComplexType { get; private set; }
 
     /// <summary>
     /// Gets a value indicating whether or not <see cref="ModelType"/> is a <see cref="Nullable{T}"/>.
@@ -647,12 +709,13 @@ public override int GetHashCode()
         return _hashCode.Value;
     }
 
+    [RequiresUnreferencedCode("Using ModelMetadata with 'Microsoft.AspNetCore.Mvc.ApiExplorer.IsEnhancedModelMetadataSupported=true' is not trim compatible.")]
+    [RequiresDynamicCode("Using ModelMetadata with 'Microsoft.AspNetCore.Mvc.ApiExplorer.IsEnhancedModelMetadataSupported=true' is not native AOT compatible.")]
     private void InitializeTypeInformation()
     {
-        Debug.Assert(ModelType != null);
-
         IsConvertibleType = TypeDescriptor.GetConverter(ModelType).CanConvertFrom(typeof(string));
         IsParseableType = FindTryParseMethod(ModelType) is not null;
+        IsComplexType = !IsConvertibleType && !IsParseableType;
         IsNullableValueType = Nullable.GetUnderlyingType(ModelType) != null;
         IsReferenceOrNullableType = !ModelType.IsValueType || IsNullableValueType;
         UnderlyingOrModelType = Nullable.GetUnderlyingType(ModelType) ?? ModelType;

src/Mvc/Mvc.Abstractions/src/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+Microsoft.AspNetCore.Mvc.ModelBinding.ModelMetadata.ModelMetadata(System.Type! type, Microsoft.AspNetCore.Http.Metadata.IParameterBindingMetadata? parameterBindingMetadata) -> void

src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs

@@ -10,7 +10,6 @@
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.Formatters;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
-using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Patterns;
 using Microsoft.Extensions.DependencyInjection;
@@ -188,7 +187,7 @@ private ApiDescription CreateApiDescription(RouteEndpoint routeEndpoint, string
         return new ApiParameterDescription
         {
             Name = name,
-            ModelMetadata = CreateModelMetadata(paramType),
+            ModelMetadata = CreateModelMetadata(paramType, parameter),
             Source = source,
             DefaultValue = parameter.ParameterInfo.DefaultValue,
             Type = parameter.ParameterInfo.ParameterType,
@@ -431,8 +430,8 @@ private static ApiResponseType CreateDefaultApiResponseType(Type responseType)
         }
     }
 
-    private static EndpointModelMetadata CreateModelMetadata(Type type) =>
-        new(ModelMetadataIdentity.ForType(type));
+    private static EndpointModelMetadata CreateModelMetadata(Type type, IParameterBindingMetadata? parameterBindingMetadata = null) =>
+        new(type, parameterBindingMetadata);
 
     private static void AddResponseContentTypes(IList<ApiResponseFormat> apiResponseFormats, IReadOnlyList<string> contentTypes)
     {

src/Mvc/Mvc.ApiExplorer/src/EndpointModelMetadata.cs

@@ -3,14 +3,15 @@
 
 using System.Collections.Immutable;
 using System.Linq;
+using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
 
 namespace Microsoft.AspNetCore.Mvc.ApiExplorer;
 
 internal sealed class EndpointModelMetadata : ModelMetadata
 {
-    public EndpointModelMetadata(ModelMetadataIdentity identity) : base(identity)
+    public EndpointModelMetadata(Type type, IParameterBindingMetadata? parameterBindingMetadata) : base(type, parameterBindingMetadata)
     {
         IsBindingAllowed = true;
     }

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.NativeAotTests/Microsoft.AspNetCore.OpenApi.NativeAotTests.proj

@@ -4,6 +4,7 @@
     <TestConsoleAppSourceFiles Include="BasicMinimalApiWithOpenApiDependency.cs">
       <EnabledProperties>EnableRequestDelegateGenerator</EnabledProperties>
       <InterceptorNamespaces>Microsoft.AspNetCore.Http.Generated</InterceptorNamespaces>
+      <DisabledFeatureSwitches>Microsoft.AspNetCore.Mvc.ApiExplorer.IsEnhancedModelMetadataSupported</DisabledFeatureSwitches>
     </TestConsoleAppSourceFiles>
   </ItemGroup>