Mongo DB Java 3.x Driver - Group By Query

Question

I\'d like to learn how to implement group by query using Mongo DB Java 3.x Driver. I want to group my collection through the usernames

Answer 1

You should try not to use old object (BasicDBObject) types with Mongo 3.x. You can try something like this.

import static com.mongodb.client.model.Accumulators.*;
import static com.mongodb.client.model.Aggregates.*;
import static java.util.Arrays.asList;

Bson group = group("$username", sum("tweetCount", 1));
Bson sort = sort(new Document("tweetCount", -1));
AggregateIterable <Document> output = collection.aggregate(asList(group, sort));