C# Driver ElemMatch bug(?) with DictionaryInterfaceImplementerSerializer

[Daniel Polistchuck]

Hi Folks,

I am receiving a System.InvalidOperationException when trying to use ElemMatch in a property that is mapped with the DictionaryInterfaceImplementerSerializer.

Here's an NUnit test that reproduces the issue:

using System;

using System.Collections.Generic;

using MongoDB.Bson.Serialization;

using MongoDB.Bson.Serialization.Options;

using MongoDB.Bson.Serialization.Serializers;

using MongoDB.Driver;

using MongoDB.Driver.Builders;

using NUnit.Framework;

namespace CredMarket.Tests

{

    [TestFixture]

    public class ElemMatchTest

    {

        [Test]

        public void TestElemMatch()

        {

            BsonClassMap.RegisterClassMap<TestClass>(cm =>

            {

                cm.AutoMap();

                cm.MapMember(c => c.EnabledForProduct)

                    .SetSerializer(new DictionaryInterfaceImplementerSerializer<Dictionary<TestProduct, bool>>(

                        DictionaryRepresentation.ArrayOfDocuments, BsonSerializer.LookupSerializer<int>(),

                        BsonSerializer.LookupSerializer<bool>())

                    );

            });

            var client = new MongoClient("mongodb://localhost");

            var database = client.GetDatabase("test");

            var collection = database.GetCollection<TestClass>("testcollection");

            collection.DeleteMany(FilterDefinition<TestClass>.Empty);

            //Creating Document

            var doc = new TestClass

            {

                Id = Guid.NewGuid().ToString(),

                EnabledForProduct = new Dictionary<TestProduct, bool>

                {

                    {TestProduct.Product1, true}

                }

            };

            collection.InsertOne(doc);

            var foundDoc = collection.Find(d=>d.Id == doc.Id).Limit(1).FirstOrDefault();

            AssertDoc(foundDoc);

            var filter = Builders<TestClass>.Filter.ElemMatch(d => d.EnabledForProduct,

                k => k.Key == TestProduct.Product1 && k.Value);

            foundDoc = collection.Find(filter).Limit(1).FirstOrDefault();

            AssertDoc(foundDoc);

        }

        private static void AssertDoc(TestClass foundDoc)

        {

            Assert.IsNotNull(foundDoc);

            Assert.IsNotNull(foundDoc.EnabledForProduct);

            Assert.IsTrue(foundDoc.EnabledForProduct[TestProduct.Product1]);

        }

    }

    public class TestClass

    {

        public string Id { get; set; }

        public Dictionary<TestProduct,bool> EnabledForProduct { get; set; }

    }

    public enum TestProduct

    {

        Product1,Product2

    }

}

The "foundDoc = collection.Find(filter).Limit(1).FirstOrDefault()" call throws the following exception:

System.InvalidOperationException : The serializer for field 'EnabledForProduct' must implement IBsonArraySerializer and provide item serialization info.

   em MongoDB.Driver.ElementMatchFilterDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)

   em MongoDB.Driver.MongoCollectionImpl`1.CreateFindOperation(FilterDefinition`1 filter, FindOptions`2 options)

   em MongoDB.Driver.MongoCollectionImpl`1.FindSync(FilterDefinition`1 filter, FindOptions`2 options, CancellationToken cancellationToken)

   em MongoDB.Driver.FindFluent`2.ToCursor(CancellationToken cancellationToken)

   em MongoDB.Driver.IAsyncCursorSourceExtensions.FirstOrDefault(IAsyncCursorSource`1 source, CancellationToken cancellationToken)

   em MongoDB.Driver.IFindFluentExtensions.FirstOrDefault(IFindFluent`2 find, CancellationToken cancellationToken)

   em CredMarket.Tests.ElemMatchTest.TestElemMatch() na ElemMatchTest.cs: line 49

Am I doing something wrong or there's actually a bug in the C# driver?

[Craig Wilson]

Hi Daniel,

It looks like you've filed https://jira.mongodb.org/browse/CSHARP-1521. I believe you've found a bug. We'll track it in that ticket.

Craig