Summary

We have a helper library on top of the driver that wraps calls to UpdateManyAsync . I will include pseudocode in the following section. All of our consumers of this library are breaking if we try and update from version 2.18 to 2.19. As I am not expecting a compatibility breaking change in a minor version update I am posting an issue to see if this is an unexpected regression.

How to Reproduce

The following code shows what we are doing.

public async Task MarkAllAsDeleted(Expression<Func<MyEntry, bool>> filter)
{
   // Define changes to apply to the database.
   var changes = new List<Tuple<Expression<Func<MyEntry, object>>, object>>();
   changes.Add(new Tuple<Expression<Func<AddressGroupEntry, object>>, object (entry => entry.Deleted, true));

   var mongoUpdateDefinition = ToMongoUpdateDefinition(changes);   

   var collection = Context.Database.GetCollection<MyEntry>(CollectionName);
   await Collection.UpdateManyAsync(filter, mongoUpdateDefinition);
   // Result handling omitted
}

public static UpdateDefinition<TEntry> ToMongoUpdateDefinition<TEntry>(List<Tuple<Expression<Func<MyEntry, object>>, object>> changes)
{
  var updates = new List<UpdateDefinition<TEntry>>();
  foreach (var change in changes)
  {
    updates.Add(Builders<TEntry>.Update.Set(change.Item1 as dynamic, change.Item2 as dynamic));
  }
  return Builders<TEntry>.Update.Combine(updates);
}

After updating to 2.19, the above code generated a callstack like:

MongoDB.Driver.Linq.ExpressionNotSupportedException: Expression not supported: Convert(entry.Deleted, Object).\n at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToFilterTranslators.ToFilterFieldTranslators.ConvertExpressionToFilterFieldTranslator.Translate(TranslationContext context, UnaryExpression expression)\n at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToFilterTranslators.ToFilterFieldTranslators.ExpressionToFilterFieldTranslator.Translate(TranslationContext context, Expression expression)\n at MongoDB.Driver.Linq.Linq3Implementation.LinqProviderAdapterV3.TranslateExpressionToField[TDocument,TField](Expression\u00601 expression, IBsonSerializer\u00601 documentSerializer, IBsonSerializerRegistry serializerRegistry, Boolean allowScalarValueForArrayField)\n at MongoDB.Driver.ExpressionFieldDefinition\u00602.Render(IBsonSerializer\u00601 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider, Boolean allowScalarValueForArrayField)\n at MongoDB.Driver.ExpressionFieldDefinition\u00602.Render(IBsonSerializer\u00601 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)\n at MongoDB.Driver.OperatorUpdateDefinition\u00602.Render(IBsonSerializer\u00601 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)\n at MongoDB.Driver.CombinedUpdateDefinition\u00601.Render(IBsonSerializer\u00601 documentSerializer, IBsonSerializerRegistry serializerRegistry, LinqProvider linqProvider)\n at MongoDB.Driver.MongoCollectionImpl\u00601.ConvertWriteModelToWriteRequest(WriteModel\u00601 model, Int32 index)\n at System.Linq.Enumerable.SelectIterator[TSource,TResult](IEnumerable\u00601 source, Func\u00603 selector)\u002BMoveNext()\n at System.Collections.Generic.List\u00601..ctor(IEnumerable\u00601 collection)\n at System.Linq.Enumerable.ToList[TSource](IEnumerable\u00601 source)\n at MongoDB.Driver.Core.Operations.BulkMixedWriteOperation..ctor(CollectionNamespace collectionNamespace, IEnumerable\u00601 requests, MessageEncoderSettings messageEncoderSettings)\n at MongoDB.Driver.MongoCollectionImpl\u00601.CreateBulkWriteOperation(IClientSessionHandle session, IEnumerable\u00601 requests, BulkWriteOptions options)\n at MongoDB.Driver.MongoCollectionImpl\u00601.BulkWriteAsync(IClientSessionHandle session, IEnumerable\u00601 requests, BulkWriteOptions options, CancellationToken cancellationToken)\n at MongoDB.Driver.MongoCollectionImpl\u00601.UsingImplicitSessionAsync[TResult](Func\u00602 funcAsync, CancellationToken cancellationToken)\n at MongoDB.Driver.MongoCollectionBase\u00601.UpdateManyAsync(FilterDefinition\u00601 filter, UpdateDefinition\u00601 update, UpdateOptions options, Func\u00603 bulkWriteAsync)\n at NationalInstruments.NotificationService.DataStore.Providers.Mongo.MongoDataProvider\u00601.UpdateAsync(Expression\u00601 match, Changes\u00601 changes) in /app/NotificationService/NotificationService.DataStore/Providers/Mongo/MongoDataProvider.cs:line 290\n

Additional Background