CSHARP-961: Add error message when deserializing a nominal type that is an interface and there is no discriminator to determine the actual type.

Author: rstam

MongoDB.Bson/Serialization/Serializers/InterfaceSerializer.cs

@@ -70,12 +70,6 @@ public override object Deserialize(
 
             var discriminatorConvention = BsonSerializer.LookupDiscriminatorConvention(nominalType);
             var actualType = discriminatorConvention.GetActualType(bsonReader, nominalType);
-            if (actualType == nominalType)
-            {
-                var message = string.Format("Unable to determine actual type of object to deserialize. NominalType is the interface {0}.", nominalType);
-                throw new FileFormatException(message);
-            }
-
             return Deserialize(bsonReader, nominalType, actualType, options);
         }
 
@@ -93,6 +87,18 @@ public override object Deserialize(
             Type actualType,
             IBsonSerializationOptions options)
         {
+            if (!nominalType.IsInterface)
+            {
+                var message = string.Format("Nominal type must be an interface, not {0}.", nominalType.FullName);
+                throw new ArgumentException(message, "nominalType");
+            }
+
+            if (actualType == nominalType)
+            {
+                var message = string.Format("Unable to determine actual type of object to deserialize. NominalType is the interface {0}.", nominalType);
+                throw new FileFormatException(message);
+            }
+
             var serializer = BsonSerializer.LookupSerializer(actualType);
             return serializer.Deserialize(bsonReader, nominalType, actualType, options);
         }

MongoDB.BsonUnitTests/Jira/CSharp961Tests.cs

@@ -0,0 +1,120 @@
+/* Copyright 2010-2014 MongoDB Inc.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System.Collections.Generic;
+using System.IO;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.Attributes;
+using MongoDB.Bson.Serialization.Conventions;
+using NUnit.Framework;
+
+namespace MongoDB.BsonUnitTests.Jira
+{
+    [TestFixture]
+    public class CSharp961Tests
+    {
+        static CSharp961Tests()
+        {
+            BsonClassMap.RegisterClassMap<Parent>();
+            BsonClassMap.RegisterClassMap<Child>();
+        }
+
+        public interface IParent
+        {
+            [BsonId]
+            BsonObjectId Id { get; set; }
+
+            [BsonElement("name")]
+            string Name { get; set; }
+
+            [BsonElement("children")]
+            Dictionary<string, IChild> StringToChildren { get; set; }
+        }
+
+        public interface IChild
+        {
+            [BsonElement("name")]
+            string Name { get; set; }
+        }
+
+        public class Parent : IParent
+        {
+            [BsonId]
+            public BsonObjectId Id { get; set; }
+
+            [BsonElement("name")]
+            public string Name { get; set; }
+
+            [BsonElement("children")]
+            public Dictionary<string, IChild> StringToChildren { get; set; }
+        }
+
+        public class Child : IChild
+        {
+            [BsonElement("name")]
+            public string Name { get; set; }
+        }
+
+        private Parent _sampleParent = new Parent
+        {
+            Id = new ObjectId("535a524abfcae300b04cea7b"),
+            Name = "ParentName",
+            StringToChildren = new Dictionary<string, IChild>
+            {
+                { "one", new Child { Name = "bob" } },
+                { "two", new Child { Name = "jane" } }
+            }
+        };
+
+        [Test]
+        public void TestDeserializeWithDiscriminator()
+        {
+            var json = "{ '_id' : ObjectId('535a524abfcae300b04cea7b'), 'name' : 'ParentName', 'children' : { 'one' : { '_t' : 'Child', 'name' : 'bob' }, 'two' : { '_t' : 'Child', 'name' : 'jane' } } }";
+            var deserializedParent = BsonSerializer.Deserialize<Parent>(json);
+            Assert.IsTrue(ParentEquals(deserializedParent, _sampleParent));
+        }
+
+        [Test]
+        public void TestDeserializeWithoutDiscriminator()
+        {
+            var json = "{ '_id' : ObjectId('535a524abfcae300b04cea7b'), 'name' : 'ParentName', 'children' : { 'one' : { 'name' : 'bob' }, 'two' : { 'name' : 'jane' } } }";
+            Assert.Throws<FileFormatException>(() => { var deserializedParent = BsonSerializer.Deserialize<Parent>(json); });
+        }
+
+        [Test]
+        public void TestSerialize()
+        {
+            var json = _sampleParent.ToJson();
+            var expected = "{ '_id' : ObjectId('535a524abfcae300b04cea7b'), 'name' : 'ParentName', 'children' : { 'one' : { '_t' : 'Child', 'name' : 'bob' }, 'two' : { '_t' : 'Child', 'name' : 'jane' } } }";
+            Assert.AreEqual(expected.Replace("'", "\""), json);
+        }
+
+        private static bool ParentEquals(Parent lhs, Parent rhs)
+        {
+            if (lhs.Id != rhs.Id) { return false; }
+            if (lhs.Name != rhs.Name) { return false; }
+            if (lhs.StringToChildren.Count != rhs.StringToChildren.Count) { return false; }
+            foreach (var pair in lhs.StringToChildren)
+            {
+                var lhsChild = pair.Value;
+                IChild rhsChild;
+                if (!rhs.StringToChildren.TryGetValue(pair.Key, out rhsChild)) { return false; }
+                if (lhsChild.Name != rhsChild.Name) { return false; }
+            }
+            return true;
+        }
+    }
+}

MongoDB.BsonUnitTests/MongoDB.BsonUnitTests.csproj

@@ -91,6 +91,7 @@
     <Compile Include="Jira\CSharp637Tests.cs" />
     <Compile Include="Jira\CSharp648Tests.cs" />
     <Compile Include="Jira\CSharp803Tests.cs" />
+    <Compile Include="Jira\CSharp961Tests.cs" />
     <Compile Include="ObjectModel\LazyBsonArrayTests.cs" />
     <Compile Include="ObjectModel\LazyBsonDocumentTests.cs" />
     <Compile Include="ObjectModel\RawBsonArrayTests.cs" />