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

Use BasicDBObjectBuilder to convert your POJO to an instance of DBObject which a DBCollection can save:

import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.DBObject;

public class Employee {
    private long no;
    private String name;

    // Getters and Setters

    public DBObject toDBObject() {
        BasicDBObjectBuilder builder = BasicDBObjectBuilder
                .start("no", no)
                .append("name", name);
        return builder.get();
    }
}

In order to save, just call toDBObject() on POJO instance and provide it to collection:

public class test {

    public static void main(String[] args) throws UnknownHostException,
            MongoException {
        ...
        DBCollection dbCollection = db.getCollection("NameColl");

        Employee employee = new Employee();
        employee.setNo(1L);
        employee.setName("yogesh");

        dbCollection.save(employee.toDBObject());
    }
}

Using this approach:

• You don't need to manually create a DBObject every time
• You don't need to mess up your POJO by extending Mongo classes (what if your POJO is already extending a class?)
• You don't need a Json mapper [and its annotations on POJO fields]
• You only have dependency to java-mongo-driver jar