Du kan omgå dette problem ved at angive dit eget AggregationExpression
.
ProjectionOperation agg = Aggregation.project() //
.and(new AggregationExpression() {
@Override
public DBObject toDbObject(AggregationOperationContext context) {
DBObject filterExpression = new BasicDBObject();
filterExpression.put("input", "$answer_list");
filterExpression.put("as", "answer");
filterExpression.put("cond", new BasicDBObject("$eq2", Arrays.<Object> asList("$$answer.question", 2)));
return new BasicDBObject("$filter", filterExpression);
}
}).as("profile");