I use the following aggregation to count "alertsources" on document "alert" that has a specifique "alertsources.date_creation" but I don't know why it counts all the alertsources instead of those who has the criteria :
final Aggregation aggregation = Aggregation.newAggregation(
                Aggregation.match(Criteria.where("alertsources.date_creation").regex(date)),
                Aggregation.match(Criteria.where("descA").is(alertName)),
                //regex(".*"+date+".*")
                Aggregation.unwind("alertsources"),
                Aggregation.unwind("descA"),
                Aggregation.group().count().as("count"));
        //System.out.println("----------"+mongoTemplate.aggregate(aggregation, Alert.class, MentionCount.class).getRawResults()+"-----");
        List<MentionCount> agregResult = mongoTemplate.aggregate(aggregation, Alert.class, MentionCount.class).getMappedResults();