com.damanzano.mongohw2_2.MongoHW2_2.java Source code

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Here is the source code for com.damanzano.mongohw2_2.MongoHW2_2.java

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package com.damanzano.mongohw2_2;

import com.mongodb.BasicDBList;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
import java.net.UnknownHostException;

/**
 *
 * @author David Andrs Maznzano Herrera <damanzano>
 */
public class MongoHW2_2 {

    public static void main(String[] args) throws UnknownHostException {
        MongoClient client = new MongoClient();
        DB db = client.getDB("students");
        DBCollection collection = db.getCollection("grades");

        DBCursor allGrades = collection.find(new BasicDBObject("type", "homework"))
                .sort(new BasicDBObject("student_id", 1).append("score", 1));
        try {
            String studentId = "";
            while (allGrades.hasNext()) {
                DBObject grade = allGrades.next();
                System.out.println(grade);
                if (!studentId.equalsIgnoreCase(((Integer) grade.get("student_id")).toString())) {
                    System.out.println("Deleting grade " + grade.get("_id").toString() + " for student "
                            + grade.get("student_id").toString());
                    collection.remove(grade);
                }
                studentId = ((Integer) grade.get("student_id")).toString();
            }
        } finally {
            allGrades.close();
        }
    }

}