Support resolving IFormFile in complex form mapping

Author: captainsafia

src/Components/Endpoints/src/FormMapping/Converters/FileConverter.cs

@@ -0,0 +1,49 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping;
+
+internal sealed class FileConverter<T>(HttpContext? httpContext) : FormDataConverter<T>, ISingleValueConverter
+{
+    [RequiresDynamicCode(FormMappingHelpers.RequiresDynamicCodeMessage)]
+    [RequiresUnreferencedCode(FormMappingHelpers.RequiresUnreferencedCodeMessage)]
+    internal override bool TryRead(ref FormDataReader reader, Type type, FormDataMapperOptions options, out T? result, out bool found)
+    {
+        if (httpContext == null)
+        {
+            result = default;
+            found = false;
+            return true;
+        }
+
+        if (typeof(T) == typeof(IFormFileCollection))
+        {
+            result = (T)httpContext.Request.Form.Files;
+            found = true;
+            return true;
+        }
+
+        var formFileCollection = httpContext.Request.Form.Files;
+        if (formFileCollection.Count == 0)
+        {
+            result = default;
+            found = false;
+            return true;
+        }
+
+        var file = formFileCollection.GetFile(reader.CurrentPrefix.ToString());
+        if (file != null)
+        {
+            result = (T)file;
+            found = true;
+            return true;
+        }
+
+        result = default;
+        found = false;
+        return true;
+    }
+}

src/Components/Endpoints/src/FormMapping/Factories/FileConverterFactory.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping;
+
+internal sealed class FileConverterFactory(IHttpContextAccessor? httpContextAccessor = null) : IFormDataConverterFactory
+{
+    [RequiresDynamicCode(FormMappingHelpers.RequiresDynamicCodeMessage)]
+    [RequiresUnreferencedCode(FormMappingHelpers.RequiresUnreferencedCodeMessage)]
+    public bool CanConvert(Type type, FormDataMapperOptions options) => type == typeof(IFormFile) || type == typeof(IFormFileCollection);
+
+    [RequiresDynamicCode(FormMappingHelpers.RequiresDynamicCodeMessage)]
+    [RequiresUnreferencedCode(FormMappingHelpers.RequiresUnreferencedCodeMessage)]
+    public FormDataConverter CreateConverter(Type type, FormDataMapperOptions options)
+    {
+        return Activator.CreateInstance(typeof(FileConverter<>).MakeGenericType(type), httpContextAccessor?.HttpContext) as FormDataConverter ??
+            throw new InvalidOperationException($"Unable to create converter for '{type.FullName}'.");
+    }
+}

src/Components/Endpoints/src/FormMapping/FormDataMapperOptions.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Concurrent;
 using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.WebUtilities;
 
 namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping;
@@ -25,6 +26,21 @@ public FormDataMapperOptions()
         _factories.Add(new ComplexTypeConverterFactory(this));
     }
 
+    [RequiresDynamicCode(FormMappingHelpers.RequiresDynamicCodeMessage)]
+    [RequiresUnreferencedCode(FormMappingHelpers.RequiresUnreferencedCodeMessage)]
+    internal FormDataMapperOptions(IHttpContextAccessor httpContextAccessor)
+    {
+        // We don't use the base constructor here since the ordering of the factories is important.
+        _converters = new(WellKnownConverters.Converters);
+        _factories.Add(new ParsableConverterFactory());
+        _factories.Add(new EnumConverterFactory());
+        _factories.Add(new FileConverterFactory(httpContextAccessor));
+        _factories.Add(new NullableConverterFactory());
+        _factories.Add(new DictionaryConverterFactory());
+        _factories.Add(new CollectionConverterFactory());
+        _factories.Add(new ComplexTypeConverterFactory(this));
+    }
+
     // Not configurable for now, this is the max number of elements we will bind. This is important for
     // security reasons, as we don't want to bind a huge collection and cause perf issues.
     // Some examples of this are:
@@ -35,7 +51,7 @@ public FormDataMapperOptions()
     // MVC uses 32, JSON uses 64. Let's stick to STJ default.
     internal int MaxRecursionDepth = 64;
 
-    // This is normally 200 (similar to ModelStateDictionary.DefaultMaxAllowedErrors in MVC) 
+    // This is normally 200 (similar to ModelStateDictionary.DefaultMaxAllowedErrors in MVC)
     internal int MaxErrorCount = 200;
 
     internal int MaxKeyBufferSize = FormReader.DefaultKeyLengthLimit;

src/Components/Endpoints/src/FormMapping/Metadata/FormDataMetadataFactory.cs

@@ -15,6 +15,7 @@ internal class FormDataMetadataFactory(List<IFormDataConverterFactory> factories
     private readonly FormMetadataContext _context = new();
     private readonly ParsableConverterFactory _parsableFactory = factories.OfType<ParsableConverterFactory>().Single();
     private readonly DictionaryConverterFactory _dictionaryFactory = factories.OfType<DictionaryConverterFactory>().Single();
+    private readonly FileConverterFactory? _fileConverterFactory = factories.OfType<FileConverterFactory>().SingleOrDefault();
     private readonly CollectionConverterFactory _collectionFactory = factories.OfType<CollectionConverterFactory>().Single();
 
     [RequiresDynamicCode(FormMappingHelpers.RequiresDynamicCodeMessage)]
@@ -67,6 +68,12 @@ public FormDataTypeMetadata GetOrCreateMetadataFor(Type type, FormDataMapperOpti
                 return result;
             }
 
+            if (_fileConverterFactory?.CanConvert(type, options) == true)
+            {
+                result.Kind = FormDataTypeKind.File;
+                return result;
+            }
+
             if (_dictionaryFactory.CanConvert(type, options))
             {
                 result.Kind = FormDataTypeKind.Dictionary;

src/Components/Endpoints/src/FormMapping/Metadata/FormDataTypeKind.cs

@@ -6,6 +6,7 @@ namespace Microsoft.AspNetCore.Components.Endpoints.FormMapping.Metadata;
 internal enum FormDataTypeKind
 {
     Primitive,
+    File,
     Collection,
     Dictionary,
     Object,

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

@@ -276,6 +276,9 @@ private static RequestDelegateFactoryContext CreateFactoryContext(RequestDelegat
         var serviceProvider = options?.ServiceProvider ?? options?.EndpointBuilder?.ApplicationServices ?? EmptyServiceProvider.Instance;
         var endpointBuilder = options?.EndpointBuilder ?? new RdfEndpointBuilder(serviceProvider);
         var jsonSerializerOptions = serviceProvider.GetService<IOptions<JsonOptions>>()?.Value.SerializerOptions ?? JsonOptions.DefaultSerializerOptions;
+        var formDataMapperOptions = serviceProvider.GetService<IHttpContextAccessor>() is {} httpContextAccessor
+            ? new FormDataMapperOptions(httpContextAccessor)
+            : new FormDataMapperOptions();
 
         var factoryContext = new RequestDelegateFactoryContext
         {
@@ -288,6 +291,7 @@ private static RequestDelegateFactoryContext CreateFactoryContext(RequestDelegat
             EndpointBuilder = endpointBuilder,
             MetadataAlreadyInferred = metadataResult is not null,
             JsonSerializerOptions = jsonSerializerOptions,
+            FormDataMapperOptions = formDataMapperOptions
         };
 
         return factoryContext;
@@ -2054,7 +2058,7 @@ private static Expression BindComplexParameterFromFormItem(
             return formArgument;
         }
 
-        var formDataMapperOptions = new FormDataMapperOptions();
+        var formDataMapperOptions = factoryContext.FormDataMapperOptions;
         var formMappingOptionsMetadatas = factoryContext.EndpointBuilder.Metadata.OfType<FormMappingOptionsMetadata>();
         foreach (var formMappingOptionsMetadata in formMappingOptionsMetadatas)
         {
@@ -2073,7 +2077,7 @@ private static Expression BindComplexParameterFromFormItem(
 
         // ProcessForm(context.Request.Form, form_dict, form_buffer);
         var processFormExpr = Expression.Call(ProcessFormMethod, FormExpr, Expression.Constant(formDataMapperOptions.MaxKeyBufferSize), formDict, formBuffer);
-        // name_reader = new FormDataReader(form_dict, CultureInfo.InvariantCulture, form_buffer.AsMemory(0, FormDataMapperOptions.MaxKeyBufferSize));
+        // name_reader = new FormDataReader(form_dict, CultureInfo.InvariantCulture, form_buffer.AsMemory(0, formDataMapperOptions.MaxKeyBufferSize));
         var initializeReaderExpr = Expression.Assign(
             formReader,
             Expression.New(FormDataReaderConstructor,

src/Http/Http.Extensions/src/RequestDelegateFactoryContext.cs

@@ -5,6 +5,7 @@
 using System.Reflection;
 using System.Text.Json;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Components.Endpoints.FormMapping;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Microsoft.AspNetCore.Http;
@@ -59,4 +60,6 @@ internal sealed class RequestDelegateFactoryContext
 
     // Grab these options upfront to avoid the per request DI scope that would be made otherwise to get the options when writing Json
     public required JsonSerializerOptions JsonSerializerOptions { get; set; }
+
+    public required FormDataMapperOptions FormDataMapperOptions { get; set; }
 }

src/Http/Http.Extensions/test/RequestDelegateFactoryTests.FormMapping.cs

@@ -5,6 +5,8 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.AspNetCore.Testing;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Primitives;
 
@@ -278,7 +280,58 @@ public async Task SupportsRecursivePropertiesWithRecursionLimit()
         var exception = await Assert.ThrowsAsync<BadHttpRequestException>(async () => await requestDelegate(httpContext));
 
         Assert.Equal("The maximum recursion depth of '3' was exceeded for 'Manager.Manager.Manager.Name'.", exception.Message);
+    }
+
+    [Fact]
+    public async Task SupportsFormFileSourcesInDto()
+    {
+        FormFileDto capturedArgument = default;
+        void TestAction([FromForm] FormFileDto args) { capturedArgument = args; };
+        var httpContext = CreateHttpContext();
+        var formFiles = new FormFileCollection
+        {
+            new FormFile(Stream.Null, 0, 10, "file", "file.txt"),
+        };
+        httpContext.Request.Form = new FormCollection(new() { { "Description", "A test file" } }, formFiles);
+        var serviceCollection = new ServiceCollection();
+        serviceCollection.TryAddSingleton<IHttpContextAccessor>(new HttpContextAccessor(httpContext));
+        var options = new RequestDelegateFactoryOptions
+        {
+            ServiceProvider = serviceCollection.BuildServiceProvider()
+        };
+
+        var factoryResult = RequestDelegateFactory.Create(TestAction, options);
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        await requestDelegate(httpContext);
+        Assert.Equal("A test file", capturedArgument.Description);
+        Assert.Equal(formFiles["file"], capturedArgument.File);
+    }
+
+    [Fact]
+    public async Task SupportsFormFileCollectionSourcesInDto()
+    {
+        FormFileCollectionDto capturedArgument = default;
+        void TestAction([FromForm] FormFileCollectionDto args) { capturedArgument = args; };
+        var httpContext = CreateHttpContext();
+        var formFiles = new FormFileCollection
+        {
+            new FormFile(Stream.Null, 0, 10, "file", "file.txt"),
+        };
+        httpContext.Request.Form = new FormCollection(new() { { "Description", "A test file" } }, formFiles);
+        var serviceCollection = new ServiceCollection();
+        serviceCollection.TryAddSingleton<IHttpContextAccessor>(new HttpContextAccessor(httpContext));
+        var options = new RequestDelegateFactoryOptions
+        {
+            ServiceProvider = serviceCollection.BuildServiceProvider()
+        };
 
+        var factoryResult = RequestDelegateFactory.Create(TestAction, options);
+        var requestDelegate = factoryResult.RequestDelegate;
+
+        await requestDelegate(httpContext);
+        Assert.Equal("A test file", capturedArgument.Description);
+        Assert.Equal(formFiles, capturedArgument.FileCollection);
     }
 
     private record TodoRecord(int Id, string Name, bool IsCompleted);
@@ -288,4 +341,26 @@ private class Employee
         public string Name { get; set; }
         public Employee Manager { get; set; }
     }
+
+    private class FormFileDto
+    {
+        public string Description { get; set; }
+        public IFormFile File { get; set; }
+    }
+
+    private class FormFileCollectionDto
+    {
+        public string Description { get; set; }
+        public IFormFileCollection FileCollection { get; set; }
+    }
+
+    private class HttpContextAccessor(HttpContext httpContext) : IHttpContextAccessor
+    {
+
+        public HttpContext HttpContext
+        {
+            get;
+            set;
+        } = httpContext;
+    }
 }