CSHARP-1351: Change ObjectSerializer to not be dependent on the order of the discriminator and value elements.

Author: rstam

src/MongoDB.Bson.Tests/Serialization/Serializers/ObjectSerializerTests.cs

@@ -1,4 +1,4 @@
-/* Copyright 2010-2014 MongoDB Inc.
+/* Copyright 2010-2015 MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -13,6 +13,7 @@
 * limitations under the License.
 */
 
+using System;
 using System.Dynamic;
 using System.Linq;
 using MongoDB.Bson;
@@ -138,6 +139,20 @@ public void TestInt64()
             Assert.IsTrue(bson.SequenceEqual(rehydrated.ToBson()));
         }
 
+        [TestCase("{ Obj : {  _v : \"01020304-0506-0708-090a-0b0c0d0e0f10\" } }")]
+        public void TestMissingDiscriminator(string json)
+        {
+            var result = BsonSerializer.Deserialize<C>(json);
+
+            Assert.IsInstanceOf<ExpandoObject>(result.Obj);
+        }
+
+        [TestCase("{ Obj : { _t : \"System.Guid\" } }")]
+        public void TestMissingValue(string json)
+        {
+            Assert.Throws<FormatException>(() => BsonSerializer.Deserialize<C>(json));
+        }
+
         [Test]
         public void TestNull()
         {
@@ -164,6 +179,24 @@ public void TestObject()
             Assert.IsTrue(bson.SequenceEqual(rehydrated.ToBson()));
         }
 
+        [TestCase("{ Obj : { _t : \"System.Object[]\", _v : [] } }")]
+        [TestCase("{ Obj : { _v : [], _t : \"System.Object[]\" } }")]
+        public void TestOrderOfElementsDoesNotMatter(string json)
+        {
+            var result = BsonSerializer.Deserialize<C>(json);
+
+            Assert.IsInstanceOf<object[]>(result.Obj);
+        }
+
+        [TestCase("{ Obj : { _t : \"System.Guid\", _v : \"01020304-0506-0708-090a-0b0c0d0e0f10\" } }", "01020304-0506-0708-090a-0b0c0d0e0f10")]
+        [TestCase("{ Obj : { _v : \"01020304-0506-0708-090a-0b0c0d0e0f10\", _t : \"System.Guid\" } }", "01020304-0506-0708-090a-0b0c0d0e0f10")]
+        public void TestOrderOfElementsDoesNotMatter(string json, string expectedGuid)
+        {
+            var result = BsonSerializer.Deserialize<C>(json);
+
+            Assert.AreEqual(Guid.Parse(expectedGuid), result.Obj);
+        }
+
         [Test]
         public void TestString()
         {

src/MongoDB.Bson/Serialization/Serializers/ObjectSerializer.cs

@@ -1,4 +1,4 @@
-/* Copyright 2010-2014 MongoDB Inc.
+/* Copyright 2010-2015 MongoDB Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@@ -249,13 +249,35 @@ private object DeserializeDiscriminatedValue(BsonDeserializationContext context,
                 }
                 else
                 {
+                    object value = null;
+                    var wasValuePresent = false;
+
                     bsonReader.ReadStartDocument();
-                    bsonReader.ReadName(_discriminatorConvention.ElementName);
-                    bsonReader.SkipValue();
-                    bsonReader.ReadName("_v");
-                    var value = serializer.Deserialize(context);
+                    while (bsonReader.ReadBsonType() != 0)
+                    {
+                        var name = bsonReader.ReadName();
+                        if (name == _discriminatorConvention.ElementName)
+                        {
+                            bsonReader.SkipValue();
+                        }
+                        else if (name == "_v")
+                        {
+                            value = serializer.Deserialize(context);
+                            wasValuePresent = true;
+                        }
+                        else
+                        {
+                            var message = string.Format("Unexpected element name: '{0}'.", name);
+                            throw new FormatException(message);
+                        }
+                    }
                     bsonReader.ReadEndDocument();
 
+                    if (!wasValuePresent)
+                    {
+                        throw new FormatException("_v element missing.");
+                    }
+
                     return value;
                 }
             }