Infer multipart/form-data for FromFile parameters

src/Microsoft.AspNetCore.Mvc.ApiExplorer/ApiBehaviorApiDescriptionProvider.cs

@@ -65,8 +65,8 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
 
             // We're looking for a name ending with Id, but preceded by a lower case letter. This should match
             // the normal PascalCase naming conventions.
-            if (parameter.Name.Length >= 3 && 
+            if (parameter.Name.Length >= 3 &&
-                parameter.Name.EndsWith("Id", StringComparison.Ordinal) && 
+                parameter.Name.EndsWith("Id", StringComparison.Ordinal) &&
                 char.IsLower(parameter.Name, parameter.Name.Length - 3))
             {
                 return true;
@@ -90,7 +90,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
 
             yield return CreateProblemResponse(statusCode: 0, isDefaultResponse: true);
         }
-        
+
         private ApiResponseType CreateProblemResponse(int statusCode, bool isDefaultResponse = false)
         {
             return new ApiResponseType

src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs

@@ -122,12 +122,32 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
 
             // It would be possible here to configure an action with multiple body parameters, in which case you
             // could end up with duplicate data.
-            foreach (var parameter in apiDescription.ParameterDescriptions.Where(p => p.Source == BindingSource.Body))
+            if (apiDescription.ParameterDescriptions.Count > 0)
             {
-                var requestFormats = GetRequestFormats(requestMetadataAttributes, parameter.Type);
+                var contentTypes = GetDeclaredContentTypes(requestMetadataAttributes);
-                foreach (var format in requestFormats)
+                foreach (var parameter in apiDescription.ParameterDescriptions)
                 {
-                    apiDescription.SupportedRequestFormats.Add(format);
+                    if (parameter.Source == BindingSource.Body)
+                    {
+                        // For request body bound parameters, determine the content types supported
+                        // by input formatters.
+                        var requestFormats = GetSupportedFormats(contentTypes, parameter.Type);
+                        foreach (var format in requestFormats)
+                        {
+                            apiDescription.SupportedRequestFormats.Add(format);
+                        }
+                    }
+                    else if (parameter.Source == BindingSource.FormFile)
+                    {
+                        // Add all declared media types since FormFiles do not get processed by formatters.
+                        foreach (var contentType in contentTypes)
+                        {
+                            apiDescription.SupportedRequestFormats.Add(new ApiRequestFormat
+                            {
+                                MediaType = contentType,
+                            });
+                        }
+                    }
                 }
             }
 
@@ -295,28 +315,17 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             return string.Join("/", segments);
         }
 
-        private IReadOnlyList<ApiRequestFormat> GetRequestFormats(
+        private IReadOnlyList<ApiRequestFormat> GetSupportedFormats(MediaTypeCollection contentTypes, Type type)
-            IApiRequestMetadataProvider[] requestMetadataAttributes,
-            Type type)
         {
-            var results = new List<ApiRequestFormat>();
-
-            // Walk through all 'filter' attributes in order, and allow each one to see or override
-            // the results of the previous ones. This is similar to the execution path for content-negotiation.
-            var contentTypes = new MediaTypeCollection();
-            if (requestMetadataAttributes != null)
-            {
-                foreach (var metadataAttribute in requestMetadataAttributes)
-                {
-                    metadataAttribute.SetContentTypes(contentTypes);
-                }
-            }
-
             if (contentTypes.Count == 0)
             {
-                contentTypes.Add((string)null);
+                contentTypes = new MediaTypeCollection
+                {
+                    (string)null,
+                };
             }
 
+            var results = new List<ApiRequestFormat>();
             foreach (var contentType in contentTypes)
             {
                 foreach (var formatter in _inputFormatters)
@@ -343,6 +352,22 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             return results;
         }
 
+        private static MediaTypeCollection GetDeclaredContentTypes(IApiRequestMetadataProvider[] requestMetadataAttributes)
+        {
+            // Walk through all 'filter' attributes in order, and allow each one to see or override
+            // the results of the previous ones. This is similar to the execution path for content-negotiation.
+            var contentTypes = new MediaTypeCollection();
+            if (requestMetadataAttributes != null)
+            {
+                foreach (var metadataAttribute in requestMetadataAttributes)
+                {
+                    metadataAttribute.SetContentTypes(contentTypes);
+                }
+            }
+
+            return contentTypes;
+        }
+
         private IReadOnlyList<ApiResponseType> GetApiResponseTypes(
             IApiResponseMetadataProvider[] responseMetadataAttributes,
             Type type)

src/Microsoft.AspNetCore.Mvc.Core/ApiBehaviorOptions.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 
 namespace Microsoft.AspNetCore.Mvc
@@ -39,10 +40,17 @@ namespace Microsoft.AspNetCore.Mvc
         /// <para>
         /// When enabled, the following sources are inferred:
         /// Parameters that appear as route values, are assumed to be bound from the path (<see cref="BindingSource.Path"/>).
+        /// Parameters of type <see cref="IFormFile"/> and <see cref="IFormFileCollection"/> are assumed to be bound from form.
         /// Parameters that are complex (<see cref="ModelMetadata.IsComplexType"/>) are assumed to be bound from the body (<see cref="BindingSource.Body"/>).
         /// All other parameters are assumed to be bound from the query.
         /// </para>
         /// </summary>
         public bool SuppressInferBindingSourcesForParameters { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value that determines if an <c>multipart/form-data</c> consumes action constraint is added to parameters
+        /// that are bound from form data.
+        /// </summary>
+        public bool SuppressConsumesConstraintForFormFileParameters { get; set; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/ApiBehaviorApplicationModelProvider.cs

@@ -78,6 +78,33 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     AddInvalidModelStateFilter(actionModel);
 
                     InferParameterBindingSources(actionModel);
+
+                    AddMultipartFormDataConsumesAttribute(actionModel);
+                }
+            }
+        }
+
+        // Internal for unit testing
+        internal void AddMultipartFormDataConsumesAttribute(ActionModel actionModel)
+        {
+            if (_apiBehaviorOptions.SuppressConsumesConstraintForFormFileParameters)
+            {
+                return;
+            }
+
+            // Add a ConsumesAttribute if the request does not explicitly specify one.
+            if (actionModel.Filters.OfType<IConsumesActionConstraint>().Any())
+            {
+                return;
+            }
+
+            foreach (var parameter in actionModel.Parameters)
+            {
+                var bindingSource = parameter.BindingInfo?.BindingSource;
+                if (bindingSource == BindingSource.FormFile)
+                {
+                    // If an action accepts files, it must accept multipart/form-data.
+                    actionModel.Filters.Add(new ConsumesAttribute("multipart/form-data"));
                 }
             }
         }
@@ -152,6 +179,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         // Internal for unit testing.
         internal BindingSource InferBindingSourceForParameter(ParameterModel parameter)
         {
+            var parameterType = parameter.ParameterInfo.ParameterType;
             if (ParameterExistsInAllRoutes(parameter.Action, parameter.ParameterName))
             {
                 return BindingSource.Path;

src/Microsoft.AspNetCore.Mvc.Core/Internal/DefaultActionConstraintProvider.cs

@@ -46,16 +46,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 return;
             }
 
-            var constraint = item.Metadata as IActionConstraint;
+            if (item.Metadata is IActionConstraint constraint)
-            if (constraint != null)
             {
                 item.Constraint = constraint;
                 item.IsReusable = true;
                 return;
             }
 
-            var factory = item.Metadata as IActionConstraintFactory;
+            if (item.Metadata is IActionConstraintFactory factory)
-            if (factory != null)
             {
                 item.Constraint = factory.CreateInstance(services);
                 item.IsReusable = factory.IsReusable;

src/Microsoft.AspNetCore.Mvc.Core/Internal/DefaultApplicationModelProvider.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.ActionConstraints;
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
@@ -217,8 +218,18 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             var attributes = propertyInfo.GetCustomAttributes(inherit: true);
             var propertyModel = new PropertyModel(propertyInfo, attributes);
             var bindingInfo = BindingInfo.GetBindingInfo(attributes);
+            if (bindingInfo != null)
+            {
+                propertyModel.BindingInfo = bindingInfo;
+            }
+            else if (IsFormFileType(propertyInfo.PropertyType))
+            {
+                propertyModel.BindingInfo = new BindingInfo
+                {
+                    BindingSource = BindingSource.FormFile,
+                };
+            }
 
-            propertyModel.BindingInfo = bindingInfo;
             propertyModel.PropertyName = propertyInfo.Name;
 
             return propertyModel;
@@ -429,7 +440,17 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             var parameterModel = new ParameterModel(parameterInfo, attributes);
 
             var bindingInfo = BindingInfo.GetBindingInfo(attributes);
-            parameterModel.BindingInfo = bindingInfo;
+            if (bindingInfo != null)
+            {
+                parameterModel.BindingInfo = bindingInfo;
+            }
+            else if (IsFormFileType(parameterInfo.ParameterType))
+            {
+                parameterModel.BindingInfo = new BindingInfo
+                {
+                    BindingSource = BindingSource.FormFile,
+                };
+            }
 
             parameterModel.ParameterName = parameterInfo.Name;
 
@@ -650,5 +671,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 list.Add(item);
             }
         }
+
+        private static bool IsFormFileType(Type parameterType)
+        {
+            return parameterType == typeof(IFormFile) ||
+                parameterType == typeof(IFormFileCollection) ||
+                typeof(IEnumerable<IFormFile>).IsAssignableFrom(parameterType);
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/Binders/FormFileModelBinderProvider.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Reflection;
 using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
@@ -22,10 +21,11 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
                 throw new ArgumentNullException(nameof(context));
             }
 
+            // Note: This condition needs to be kept in sync with ApiBehaviorApplicationModelProvider.
             var modelType = context.Metadata.ModelType;
             if (modelType == typeof(IFormFile) ||
                 modelType == typeof(IFormFileCollection) ||
-                typeof(IEnumerable<IFormFile>).GetTypeInfo().IsAssignableFrom(modelType.GetTypeInfo()))
+                typeof(IEnumerable<IFormFile>).IsAssignableFrom(modelType))
             {
                 return new FormFileModelBinder();
             }

test/Microsoft.AspNetCore.Mvc.ApiExplorer.Test/DefaultApiDescriptionProviderTest.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Reflection;
 using System.Text;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ActionConstraints;
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
@@ -990,6 +991,31 @@ namespace Microsoft.AspNetCore.Mvc.Description
             Assert.Equal(typeof(string), parameter.Type);
         }
 
+        [Fact]
+        public void GetApiDescription_ParameterDescription_SourceFromFormFile()
+        {
+            // Arrange
+            var action = CreateActionDescriptor(nameof(AcceptsFormFile));
+            action.FilterDescriptors = new[]
+            {
+                new FilterDescriptor(new ConsumesAttribute("multipart/form-data"), FilterScope.Action),
+            };
+
+            // Act
+            var descriptions = GetApiDescriptions(action);
+
+            // Assert
+            var description = Assert.Single(descriptions);
+
+            var parameters = description.ParameterDescriptions;
+            var parameter = Assert.Single(parameters);
+            Assert.Same(BindingSource.FormFile, parameter.Source);
+
+            var requestFormat = Assert.Single(description.SupportedRequestFormats);
+            Assert.Equal("multipart/form-data", requestFormat.MediaType);
+            Assert.Null(requestFormat.Formatter);
+        }
+
         [Fact]
         public void GetApiDescription_ParameterDescription_SourceFromHeader()
         {
@@ -1534,6 +1560,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
         {
         }
 
+        private void AcceptsFormFile([FromFormFile] IFormFile formFile)
+        {
+        }
+
         // This will show up as source = model binding
         private void AcceptsProduct_Default([ModelBinder] Product product)
         {
@@ -1856,5 +1886,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
         {
 
         }
+
+        private class FromFormFileAttribute : Attribute, IBindingSourceMetadata
+        {
+            public BindingSource BindingSource => BindingSource.FormFile;
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ApiBehaviorApplicationModelProviderTest.cs

@@ -5,6 +5,7 @@ using System;
 using System.ComponentModel;
 using System.Linq;
 using System.Reflection;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
@@ -36,10 +37,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             // Arrange
             var context = GetContext(typeof(TestApiController));
-            var options = Options.Create(new ApiBehaviorOptions
+            var options = new ApiBehaviorOptions
             {
                 SuppressModelStateInvalidFilter = true,
-            });
+            };
 
             var provider = GetProvider(options);
 
@@ -79,10 +80,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             // Arrange
             var context = GetContext(typeof(SimpleController));
-            var options = Options.Create(new ApiBehaviorOptions
+            var options = new ApiBehaviorOptions
             {
                 SuppressModelStateInvalidFilter = true,
-            });
+            };
 
             var provider = GetProvider(options);
 
@@ -107,10 +108,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             // Arrange
             var context = GetContext(typeof(TestApiController));
-            var options = Options.Create(new ApiBehaviorOptions
+            var options = new ApiBehaviorOptions
             {
                 SuppressModelStateInvalidFilter = true,
-            });
+            };
 
             var provider = GetProvider(options);
 
@@ -128,10 +129,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // Arrange
             var context = GetContext(typeof(TestApiController));
             context.Result.Controllers[0].ApiExplorer.IsVisible = false;
-            var options = Options.Create(new ApiBehaviorOptions
+            var options = new ApiBehaviorOptions
             {
                 SuppressModelStateInvalidFilter = true,
-            });
+            };
 
             var provider = GetProvider(options);
 
@@ -397,18 +398,82 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             Assert.Same(BindingSource.Query, result);
         }
 
+        [Fact]
+        public void AddMultipartFormDataConsumesAttribute_NoOpsIfBehaviorIsDisabled()
+        {
+            // Arrange
+            var actionName = nameof(ParameterBindingController.FromFormParameter);
+            var action = GetActionModel(typeof(ParameterBindingController), actionName);
+            var options = new ApiBehaviorOptions
+            {
+                SuppressConsumesConstraintForFormFileParameters = true,
+                InvalidModelStateResponseFactory = _ => null,
+            };
+            var provider = GetProvider(options);
+
+            // Act
+            provider.AddMultipartFormDataConsumesAttribute(action);
+
+            // Assert
+            Assert.Empty(action.Filters);
+        }
+
+        [Fact]
+        public void AddMultipartFormDataConsumesAttribute_NoOpsIfConsumesConstraintIsAlreadyPresent()
+        {
+            // Arrange
+            var actionName = nameof(ParameterBindingController.ActionWithConsumesAttribute);
+            var action = GetActionModel(typeof(ParameterBindingController), actionName);
+            var options = new ApiBehaviorOptions
+            {
+                SuppressConsumesConstraintForFormFileParameters = true,
+                InvalidModelStateResponseFactory = _ => null,
+            };
+            var provider = GetProvider(options);
+
+            // Act
+            provider.AddMultipartFormDataConsumesAttribute(action);
+
+            // Assert
+            var attribute = Assert.Single(action.Filters);
+            var consumesAttribute = Assert.IsType<ConsumesAttribute>(attribute);
+            Assert.Equal("application/json", Assert.Single(consumesAttribute.ContentTypes));
+        }
+
+        [Fact]
+        public void AddMultipartFormDataConsumesAttribute_AddsConsumesAttribute_WhenActionHasFromFormFileParameter()
+        {
+            // Arrange
+            var actionName = nameof(ParameterBindingController.FormFileParameter);
+            var action = GetActionModel(typeof(ParameterBindingController), actionName);
+            action.Parameters[0].BindingInfo = new BindingInfo
+            {
+                BindingSource = BindingSource.FormFile,
+            };
+            var provider = GetProvider();
+
+            // Act
+            provider.AddMultipartFormDataConsumesAttribute(action);
+
+            // Assert
+            var attribute = Assert.Single(action.Filters);
+            var consumesAttribute = Assert.IsType<ConsumesAttribute>(attribute);
+            Assert.Equal("multipart/form-data", Assert.Single(consumesAttribute.ContentTypes));
+        }
+
         private static ApiBehaviorApplicationModelProvider GetProvider(
-            IOptions<ApiBehaviorOptions> options = null,
+            ApiBehaviorOptions options = null,
             IModelMetadataProvider modelMetadataProvider = null)
         {
-            options = options ?? Options.Create(new ApiBehaviorOptions
+            options = options ?? new ApiBehaviorOptions
             {
                 InvalidModelStateResponseFactory = _ => null,
-            });
+            };
+            var optionsProvider = Options.Create(options);
             modelMetadataProvider = modelMetadataProvider ?? new TestModelMetadataProvider();
             var loggerFactory = NullLoggerFactory.Instance;
 
-            return new ApiBehaviorApplicationModelProvider(options, modelMetadataProvider, loggerFactory);
+            return new ApiBehaviorApplicationModelProvider(optionsProvider, modelMetadataProvider, loggerFactory);
         }
 
         private static ApplicationModelProviderContext GetContext(Type type)
@@ -418,11 +483,16 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             return context;
         }
 
-        private static ParameterModel GetParameterModel(Type controllerType, string actionName)
+        private static ActionModel GetActionModel(Type controllerType, string actionName)
         {
             var context = GetContext(controllerType);
             var controller = Assert.Single(context.Result.Controllers);
-            var action = Assert.Single(controller.Actions, m => m.ActionName == actionName);
+            return Assert.Single(controller.Actions, m => m.ActionName == actionName);
+        }
+
+        private static ParameterModel GetParameterModel(Type controllerType, string actionName)
+        {
+            var action = GetActionModel(controllerType, actionName);
             return Assert.Single(action.Parameters);
         }
 
@@ -487,6 +557,22 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
             [HttpPut("put-action/{id}")]
             public IActionResult SimpleTypeModel(ConvertibleFromString model) => null;
+
+            [HttpPost("form-file")]
+            public IActionResult FormFileParameter(IFormFile formFile) => null;
+
+            [HttpPost("form-file-collection")]
+            public IActionResult FormFileCollectionParameter(IFormFileCollection formFiles) => null;
+
+            [HttpPost("form-file-sequence")]
+            public IActionResult FormFileSequenceParameter(IFormFile[] formFiles) => null;
+
+            [HttpPost]
+            public IActionResult FromFormParameter([FromForm] string parameter) => null;
+
+            [HttpPost]
+            [Consumes("application/json")]
+            public IActionResult ActionWithConsumesAttribute([FromForm] string parameter) => null;
         }
 
         [ApiController]

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/DefaultApplicationModelProviderTest.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.ApplicationModels;
 using Microsoft.AspNetCore.Mvc.Filters;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
@@ -45,13 +46,74 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             builder.OnProvidersExecuting(context);
 
             // Assert
-            var model = Assert.Single(context.Result.Controllers);
+            var controllerModel = Assert.Single(context.Result.Controllers);
-            Assert.Equal(2, model.ControllerProperties.Count);
+            Assert.Collection(
-            Assert.Equal("Bound", model.ControllerProperties[0].PropertyName);
+                controllerModel.ControllerProperties.OrderBy(p => p.PropertyName),
-            Assert.Equal(BindingSource.Query, model.ControllerProperties[0].BindingInfo.BindingSource);
+                property =>
-            Assert.NotNull(model.ControllerProperties[0].Controller);
+                {
-            var attribute = Assert.Single(model.ControllerProperties[0].Attributes);
+                    Assert.Equal(nameof(ModelBinderController.Bound), property.PropertyName);
-            Assert.IsType<FromQueryAttribute>(attribute);
+                    Assert.Equal(BindingSource.Query, property.BindingInfo.BindingSource);
+                    Assert.Same(controllerModel, property.Controller);
+
+                    var attribute = Assert.Single(property.Attributes);
+                    Assert.IsType<FromQueryAttribute>(attribute);
+                },
+                property =>
+                {
+                    Assert.Equal(nameof(ModelBinderController.FormFile), property.PropertyName);
+                    Assert.Equal(BindingSource.FormFile, property.BindingInfo.BindingSource);
+                    Assert.Same(controllerModel, property.Controller);
+
+                    Assert.Empty(property.Attributes);
+                },
+                property =>
+                {
+                    Assert.Equal(nameof(ModelBinderController.Unbound), property.PropertyName);
+                    Assert.Null(property.BindingInfo);
+                    Assert.Same(controllerModel, property.Controller);
+                });
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_AddsBindingSources_ForActionParameters()
+        {
+            // Arrange
+            var builder = new TestApplicationModelProvider();
+            var typeInfo = typeof(ModelBinderController).GetTypeInfo();
+
+            var context = new ApplicationModelProviderContext(new[] { typeInfo });
+
+            // Act
+            builder.OnProvidersExecuting(context);
+
+            // Assert
+            var controllerModel = Assert.Single(context.Result.Controllers);
+            var action = Assert.Single(controllerModel.Actions);
+            Assert.Collection(
+                action.Parameters,
+                parameter =>
+                {
+                    Assert.Equal("fromQuery", parameter.ParameterName);
+                    Assert.Equal(BindingSource.Query, parameter.BindingInfo.BindingSource);
+                    Assert.Same(action, parameter.Action);
+
+                    var attribute = Assert.Single(parameter.Attributes);
+                    Assert.IsType<FromQueryAttribute>(attribute);
+                },
+                parameter =>
+                {
+                    Assert.Equal("formFileCollection", parameter.ParameterName);
+                    Assert.Equal(BindingSource.FormFile, parameter.BindingInfo.BindingSource);
+                    Assert.Same(action, parameter.Action);
+
+                    Assert.Empty(parameter.Attributes);
+                },
+                parameter =>
+                {
+                    Assert.Equal("unbound", parameter.ParameterName);
+                    Assert.Null(parameter.BindingInfo);
+                    Assert.Same(action, parameter.Action);
+                });
         }
 
         // This class has a filter attribute, but doesn't implement any filter interfaces,
@@ -1297,6 +1359,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             public string Bound { get; set; }
 
             public string Unbound { get; set; }
+
+            public IFormFile FormFile { get; set; }
+
+            public IActionResult PostAction([FromQuery] string fromQuery, IFormFileCollection formFileCollection, string unbound) => null;
         }
 
         public class SomeFiltersController : IAsyncActionFilter, IResultFilter

test/Microsoft.AspNetCore.Mvc.FunctionalTests/ApiExplorerTest.cs

@@ -1144,6 +1144,19 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
                 });
         }
 
+        [Fact]
+        public async Task ApiBehavior_AddsMultipartFormDataConsumesConstraint_ForActionsWithFormFileParameters()
+        {
+            // Act
+            var body = await Client.GetStringAsync("ApiExplorerApiController/ActionWithFormFileCollectionParameter");
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            var requestFormat = Assert.Single(description.SupportedRequestFormats);
+            Assert.Equal("multipart/form-data", requestFormat.MediaType);
+        }
+
         private void AssertProblemDetails(ApiExplorerResponseType response)
         {
             Assert.Equal("Microsoft.AspNetCore.Mvc.ProblemDetails", response.ResponseType);
@@ -1172,6 +1185,8 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             public string RelativePath { get; set; }
 
             public List<ApiExplorerResponseType> SupportedResponseTypes { get; } = new List<ApiExplorerResponseType>();
+
+            public List<ApiExplorerRequestFormat> SupportedRequestFormats { get; } = new List<ApiExplorerRequestFormat>();
         }
 
         // Used to serialize data between client and server
@@ -1215,5 +1230,12 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
 
             public string FormatterType { get; set; }
         }
+
+        private class ApiExplorerRequestFormat
+        {
+            public string MediaType { get; set; }
+
+            public string FormatterType { get; set; }
+        }
     }
 }

test/WebSites/ApiExplorerWebSite/ApiExplorerDataFilter.cs

@@ -84,6 +84,15 @@ namespace ApiExplorerWebSite
                 data.ParameterDescriptions.Add(parameterData);
             }
 
+            foreach (var request in description.SupportedRequestFormats)
+            {
+                data.SupportedRequestFormats.Add(new ApiExplorerRequestFormat
+                {
+                    FormatterType = request.Formatter?.GetType().FullName,
+                    MediaType = request.MediaType,
+                });
+            }
+
             foreach (var response in description.SupportedResponseTypes)
             {
                 var responseType = new ApiExplorerResponseType()
@@ -120,6 +129,8 @@ namespace ApiExplorerWebSite
             public string RelativePath { get; set; }
 
             public List<ApiExplorerResponseType> SupportedResponseTypes { get; } = new List<ApiExplorerResponseType>();
+
+            public List<ApiExplorerRequestFormat> SupportedRequestFormats { get; } = new List<ApiExplorerRequestFormat>();
         }
 
         // Used to serialize data between client and server
@@ -163,5 +174,12 @@ namespace ApiExplorerWebSite
 
             public string FormatterType { get; set; }
         }
+
+        private class ApiExplorerRequestFormat
+        {
+            public string MediaType { get; set; }
+
+            public string FormatterType { get; set; }
+        }
     }
 }

test/WebSites/ApiExplorerWebSite/Controllers/ApiExplorerApiController.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Http;
 
 namespace ApiExplorerWebSite
 {
@@ -22,5 +23,9 @@ namespace ApiExplorerWebSite
         public void ActionWithIdSuffixParameter(int personId, string personName)
         {
         }
+
+        public void ActionWithFormFileCollectionParameter(IFormFileCollection formFile)
+        {
+        }
     }
 }