Cannot deserialize a 'Int32' from BsonType 'Null' for deleted object by TTL on find query

Working with Data Connectors & Integrations
,
1

What I have:
Collection with TTL index.
Need to execute find query on collection.

What SOMETIMES I get:
Exception: System.FormatException: An error occurred while deserializing the Hourly property of class ClassRow: An error occurred while deserializing the Subscribers property of class ClassRow+Counters: An error occurred while deserializing the CountDiff property of class ClassRow+Subscribers: Cannot deserialize a 'Int32' from BsonType 'Null'.

My query code:
return await _rowsCollection.Find(filter})Limit(limit).ToListAsync();

What i guess is the cause:
Order of execution:

  1. Start find query
  2. Find ids by index(not ttl). Example: id1,id2,id3 to return
  3. TTL thread remove object with id2
  4. Mongo tries to read and deserialize objects with id1,id2,id3, but get an error on deserializing object with id2, coz its null now

Is there any way not to get an exception(ignore some of desserialization errors), but simply ignore it, and get 99 objects instead of 100, as example?

2

Full stack trace:

System.FormatException: Cannot deserialize a 'Int32' from BsonType 'Null'.
  at
MongoDB.Bson.Serialization.Serializers.Int32Serializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.Serializers.SerializerBase`1.MongoDB.Bson.Serialization.IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize(IBsonSerializer serializer, BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  --- End of inner exception stack trace ---
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeClass(BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.Serializers.SerializerBase`1.MongoDB.Bson.Serialization.IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize(IBsonSerializer serializer, BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  --- End of inner exception stack trace ---
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeClass(BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.Serializers.SerializerBase`1.MongoDB.Bson.Serialization.IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize(IBsonSerializer serializer, BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  --- End of inner exception stack trace ---
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeClass(BsonDeserializationContext context)
  at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
  at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize[TValue](IBsonSerializer`1 serializer, BsonDeserializationContext context)
  at MongoDB.Driver.Core.Operations.CursorBatchDeserializationHelper.DeserializeBatch[TDocument](RawBsonArray batch, IBsonSerializer`1 documentSerializer, MessageEncoderSettings messageEncoderSettings)
  at MongoDB.Driver.Core.Operations.FindCommandOperation`1.CreateFirstCursorBatch(BsonDocument cursorDocument)
  at MongoDB.Driver.Core.Operations.FindCommandOperation`1.CreateCursor(IChannelSourceHandle channelSource, IChannelHandle channel, BsonDocument commandResult)
  at MongoDB.Driver.Core.Operations.FindCommandOperation`1.ExecuteAsync(RetryableReadContext context, CancellationToken cancellationToken)
  at MongoDB.Driver.Core.Operations.FindOperation`1.ExecuteAsync(RetryableReadContext context, CancellationToken cancellationToken)
  at MongoDB.Driver.Core.Operations.FindOperation`1.ExecuteAsync(IReadBinding binding, CancellationToken cancellationToken)
  at MongoDB.Driver.OperationExecutor.ExecuteReadOperationAsync[TResult](IReadBinding binding, IReadOperation`1 operation, CancellationToken cancellationToken)
  at MongoDB.Driver.MongoCollectionImpl`1.ExecuteReadOperationAsync[TResult](IClientSessionHandle session, IReadOperation`1 operation, ReadPreference readPreference, CancellationToken cancellationToken)
  at MongoDB.Driver.MongoCollectionImpl`1.UsingImplicitSessionAsync[TResult](Func`2 funcAsync, CancellationToken cancellationToken)
  at MongoDB.Driver.IAsyncCursorSourceExtensions.ToListAsync[TDocument](IAsyncCursorSource`1 source, CancellationToken cancellationToken)
  at
MyMethod()
3

I think a more straightforward explanation of what is happening is that you actually have some documents where the CountDiff element is null in the database.

Perhaps you only get this error sometimes because it depends on which documents match your filter.

If null is a valid value for CountDiff you can declare the CountDiff property of be of type int? instead of int.

4

Its not valid case where CountDiff is null. Its retriction on write-side code. So I guess this is caused by TTL