Modified FormCollectionModelBinderProvider to throw when binding for …

…FormCollection model type.

[Fixes aspnet#4895] No parameterless Constructor defined

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

@@ -2,7 +2,9 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Reflection;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Core;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
 {
@@ -19,7 +21,18 @@ public IModelBinder GetBinder(ModelBinderProviderContext context)
                 throw new ArgumentNullException(nameof(context));
             }
 
-            if (context.Metadata.ModelType == typeof(IFormCollection))
+            var modelType = context.Metadata.ModelType;
+
+            if (typeof(FormCollection).GetTypeInfo().IsAssignableFrom(modelType))
+            {
+                throw new InvalidOperationException(
+                    Resources.FormatFormCollectionModelBinder_CannotBindToFormCollection(
+                        typeof(FormCollectionModelBinder).FullName,
+                        modelType.FullName,
+                        typeof(IFormCollection).FullName));
+            }
+
+            if (modelType == typeof(IFormCollection))
             {
                 return new FormCollectionModelBinder();
             }

src/Microsoft.AspNetCore.Mvc.Core/Resources.resx

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
-  <!--
-    Microsoft ResX Schema
-
+  <!-- 
+    Microsoft ResX Schema 
+    
     Version 2.0
-
-    The primary goals of this format is to allow a simple XML format
-    that is mostly human readable. The generation and parsing of the
-    various data types are done through the TypeConverter classes
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
     associated with the data types.
-
+    
     Example:
-
+    
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,36 +26,36 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-
-    There are any number of "resheader" rows that contain simple
+                
+    There are any number of "resheader" rows that contain simple 
     name/value pairs.
-
-    Each data row contains a name, and value. The row also contains a
-    type or mimetype. Type corresponds to a .NET class that support
-    text/value conversion through the TypeConverter architecture.
-    Classes that don't support this are serialized and stored with the
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
     mimetype set.
-
-    The mimetype is used for serialized objects, and tells the
-    ResXResourceReader how to depersist the object. This is currently not
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
     extensible. For a given mimetype the value must be set accordingly:
-
-    Note - application/x-microsoft.net.object.binary.base64 is the format
-    that the ResXResourceWriter will generate, however the reader can
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
     read any of the formats listed below.
-
+    
     mimetype: application/x-microsoft.net.object.binary.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-
+    
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array
+    value   : The object must be serialized into a byte array 
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
@@ -373,4 +373,7 @@
   <data name="AuthorizeFilter_AuthorizationPolicyCannotBeCreated" xml:space="preserve">
     <value>An {0} cannot be created without a valid instance of {1}.</value>
   </data>
+  <data name="FormCollectionModelBinder_CannotBindToFormCollection" xml:space="preserve">
+    <value>The '{0}' cannot bind to a model of type '{1}'. Change the model type to '{2}' instead.</value>
+  </data>
 </root>

test/Microsoft.AspNetCore.Mvc.Core.Test/ModelBinding/Binders/FormCollectionModelBinderProviderTest.cs

@@ -12,6 +12,22 @@ public class FormCollectionModelBinderProviderTest
     {
         [Theory]
         [InlineData(typeof(FormCollection))]
+        [InlineData(typeof(DerviedFormCollection))]
+        public void Create_ThrowsException_ForFormCollectionModelType(Type modelType)
+        {
+            // Arrange
+            var provider = new FormCollectionModelBinderProvider();
+            var context = new TestModelBinderProviderContext(modelType);
+
+            // Act & Assert
+            var exception = Assert.Throws<InvalidOperationException>(() => provider.GetBinder(context));
+
+            Assert.Equal(
+                $"The '{typeof(FormCollectionModelBinder).FullName}' cannot bind to a model of type '{modelType.FullName}'. Change the model type to '{typeof(IFormCollection).FullName}' instead.",
+                exception.Message);
+        }
+
+        [Theory]
         [InlineData(typeof(TestClass))]
         [InlineData(typeof(IList<int>))]
         [InlineData(typeof(int[]))]
@@ -45,5 +61,10 @@ public void Create_ForFormCollectionToken_ReturnsBinder()
         private class TestClass
         {
         }
+
+        private class DerviedFormCollection : FormCollection
+        {
+            public DerviedFormCollection() : base(fields: null, files: null) { }
+        }
     }
 }