Inserting Java Object to MongoDB Collection Using Java

Question

I am trying to insert a whole Java object into a MongoDB Collection using Java. I am getting following error:

Error :

Exception in t         


        

Answer 1

Hopefully this will work for you and you can get help from it. I performed database operations(insert,delete, update, get, getall) and used Person object for operations in MongoDB with java for demo purpose.

1. Database connection class

Connection.java

package test;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.codecs.pojo.PojoCodecProvider;
import static org.bson.codecs.configuration.CodecRegistries.fromProviders;
import static org.bson.codecs.configuration.CodecRegistries.fromRegistries;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.client.MongoDatabase;

public class Connection {
    public MongoClient mongo;
    private String db;
    public MongoDatabase database;
    private static Connection instance;

    private Connection() {
        db = "chatsystem";
        CodecRegistry pojoCodecRegistry = fromRegistries(MongoClient.getDefaultCodecRegistry(),
                fromProviders(PojoCodecProvider.builder().automatic(true).build()));
        mongo = new MongoClient("localhost", MongoClientOptions.builder().codecRegistry(pojoCodecRegistry).build());
        database = mongo.getDatabase(db);

    }

    public static Connection getInstance() {
        if (instance == null) {
            instance = new Connection();
            return instance;
        } else {
            return instance;
        }
    }

}

2. Model Class

Person.java

package test;

import org.bson.types.ObjectId;

public class Person {

    public Person() {
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getFname() {
        return fname;
    }

    public void setFname(String fname) {
        this.fname = fname;
    }

    public String getLname() {
        return lname;
    }

    public void setLname(String lname) {
        this.lname = lname;
    }

    private ObjectId id;

    public Person(String username, String email, String password, String fname, String lname) {
        super();
        this.username = username;
        this.email = email;
        this.password = password;
        this.fname = fname;
        this.lname = lname;
    }

    public ObjectId getId() {
        return id;
    }

    public void setId(ObjectId id) {
        this.id = id;
    }

    private String username;
    private String email;
    private String password;
    private String fname;
    private String lname;
}

3. Main class

test.java

package test;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import static com.mongodb.client.model.Filters.*;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;

public class test {
    private MongoCollection person;
    Connection conn;
    public void getCollection() {
        conn = Connection.getInstance();
        person = conn.database.getCollection("person", Person.class);
    }
    public static void main(String[] args) throws Exception {
        test t = new test();
        t.getCollection();
        Person p = new Person();
        p.setEmail("test@test.com");
        p.setFname("ftest");
        p.setLname("ltest");
        p.setPassword("testtest");
        p.setUsername("test123");


        // insert person type objects in database
        t.insertPerson(p);


        // get all persons from database
        List pp = t.getAllPersons();
        Person pt = pp.get(0);
        System.out.println(pt.getEmail());
        System.out.println(pt.getId());


        // get one person from database by username filter

                 // pass username of person in method argument
        Person ph = t.getOnePerson("test123");
        System.out.println(ph.getEmail());
        System.out.println(ph.getId());


        // update/edit person by username filter
                // pass username of person in method argument
        t.updatePerson("test123");


        // delete person by username filter
               // pass username of person in method argument
        t.removePerson("updatetest123");

    }

    public void insertPerson(Person p) {

        person.insertOne(p);
    }

    public List getAllPersons() {
        FindIterable iterable = person.find();
        Iterator it = iterable.iterator();
        List allPersons = new ArrayList<>();
        while (it.hasNext()) {
            Person per = (Person) it.next();
            allPersons.add(per);
        }
        return allPersons;
    }

    public Person getOnePerson(String username) {
        return person.find(eq("username", username)).first();
    }

    public void updatePerson(String username) {
        Person p = new Person();
        p.setEmail("update@test.com");
        p.setFname("updateftest");
        p.setLname("updateltest");
        p.setPassword("updatetesttest");
        p.setUsername("updatetest123");
        person.replaceOne(eq("username", username), p);

    }

    public void removePerson(String username) {
        person.deleteOne(eq("username", username));
    }



}