com.mycompany.mongodb_exercise.MongoDBQueries.java Source code

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Here is the source code for com.mycompany.mongodb_exercise.MongoDBQueries.java

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package com.mycompany.mongodb_exercise;

import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.client.AggregateIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.bson.Document;

/**
 *
 * @author jonassimonsen
 */
public class MongoDBQueries {

    private String clientURI;
    private String dbName;
    private String collectionName;
    private MongoDatabase db;
    MongoCollection<Document> collection;

    public MongoDBQueries(String clientURI, String dbName, String collectionName) {
        this.clientURI = clientURI;
        this.dbName = dbName;
        this.collectionName = collectionName;
        MongoClientURI connStr = new MongoClientURI(clientURI);
        MongoClient mongoClient = new MongoClient(connStr);
        db = mongoClient.getDatabase(dbName);
        collection = db.getCollection(collectionName);
    }

    /**
     * How many users are there in our database?
     *
     * @return list of results
     */
    public int getNumberOfUsersInDatabase() {
        AggregateIterable<Document> output = collection
                .aggregate(Arrays.asList(new Document("$group", new Document("_id", "$user")), // Collects a group of all users.
                        new Document("$group", new Document("_id", null).append("count", new Document("$sum", 1))), // Calculating the sum for the retrieved group of users from the previous line, putting the result of $sum into a variable called "count".
                        new Document("$project", new Document("_id", 0).append("count", 1)) // Returns, with the append specifying the inclusion of the field "count" in the return result.
        ));

        int numberOfUsersInDatabase = 0;
        for (Document dbObject : output) {
            numberOfUsersInDatabase = (int) dbObject.get("count");
        }

        return numberOfUsersInDatabase;
    }

    /**
     * Which Twitter users link the most to other Twitter users? (Provide the
     * top ten.)
     *
     * @return list of results
     */
    public List<Object> getTopTenActiveUsers() {
        AggregateIterable<Document> output = collection.aggregate(Arrays.asList(
                // "user","$user" meaning that we are creating a variable called "user", and then we are inserting variables from every user by saying $user.
                // We could, for example, write '11' and we would create 'user' variables only for user number 11.
                new Document("$group",
                        new Document("_id", new Document("user", "$user").append("tweet_id", "$id"))), // Get sets of every user and tweet association.
                new Document("$group",
                        new Document("_id", "$_id.user").append("tweet_count", new Document("$sum", 1))), // Get the sum of every occurence of a unique user id.
                new Document("$project", new Document("_id", 0).append("user", "$_id").append("tweet_count", 1)), // Cuts off unnecessary data, leaving us with only the users and their tweet counts.
                new Document("$sort", new Document("tweet_count", -1)), //-1 sorts in descending order.
                new Document("$limit", 10) // Get the top 10 users.
        )).allowDiskUse(Boolean.TRUE);

        List<Object> topTenActiveUsers = new ArrayList<>();
        for (Document dbObject : output) {
            topTenActiveUsers.add(dbObject.get("user") + ", " + dbObject.get("tweet_count"));
        }

        return topTenActiveUsers;
    }

    /**
     * Who are the most active users? (Provide top ten.)
     *
     * @return list of results
     */
    public List<Object> getTopTenLinkedUsers() {
        AggregateIterable<Document> output = collection.aggregate(Arrays.asList(
                new Document("$match", new Document("text", new Document("$regex", ".*@.*"))),
                new Document("$group",
                        new Document("_id", new Document("user", "$user").append("tweet_id", "$id"))),
                new Document("$group",
                        new Document("_id", "$_id.user").append("tweet_count", new Document("$sum", 1))),
                new Document("$project", new Document("_id", 0).append("user", "$_id").append("tweet_count", 1)),
                new Document("$sort", new Document("tweet_count", -1)), new Document("$limit", 10)))
                .allowDiskUse(Boolean.TRUE);

        List<Object> topTenLinkedUsers = new ArrayList<>();
        for (Document dbObject : output) {
            topTenLinkedUsers.add(dbObject.get("user") + ", " + dbObject.get("tweet_count"));
        }

        return topTenLinkedUsers;
    }

    /**
     * Who are the most happy? (most positive tweets.)
     *
     * @return list of results
     */
    public List<Object> getHappyUsers() {
        AggregateIterable<Document> output = collection
                .aggregate(Arrays.asList(
                        new Document("$project",
                                new Document("_id", 0).append("user", "$_id").append("polarity", 1).append("user",
                                        1)),
                        new Document("$sort", new Document("polarity", -1)), new Document("$limit", 5)))
                .allowDiskUse(Boolean.TRUE);

        List<Object> topHappyUsers = new ArrayList<>();
        for (Document dbObject : output) {
            topHappyUsers.add(dbObject.get("user") + ", " + dbObject.get("polarity"));
        }

        return topHappyUsers;
    }

    /**
     * Who are the five most grumpy? (most negative tweets.)
     *
     * @return list of results
     */
    public List<Object> getGrumpyUsers() {
        AggregateIterable<Document> output = collection
                .aggregate(Arrays.asList(
                        new Document("$project",
                                new Document("_id", 0).append("user", "$_id").append("polarity", 1).append("user",
                                        1)),
                        new Document("$sort", new Document("polarity", 1)), new Document("$limit", 5)))
                .allowDiskUse(Boolean.TRUE);

        List<Object> topHappyUsers = new ArrayList<>();
        for (Document dbObject : output) {
            topHappyUsers.add(dbObject.get("user") + ", " + dbObject.get("polarity"));
        }

        return topHappyUsers;
    }

    /**
     * Who are the most mentioned Twitter users? (Provide top five.)
     *
     * @return list of results
     */
    public List<Object> getMostMentionedUsers() {
        MongoCollection<Document> mentionCollection = db.getCollection("most_mentioned");

        AggregateIterable<Document> output = mentionCollection
                .aggregate(
                        Arrays.asList(new Document("$sort", new Document("value", -1)), new Document("$limit", 5)))
                .allowDiskUse(Boolean.TRUE);

        List<Object> topFiveMentionedUsers = new ArrayList<>();

        for (Document dbObject : output) {

            topFiveMentionedUsers.add(dbObject.get("_id") + ", " + dbObject.get("value"));

        }

        return topFiveMentionedUsers;
    }

}