how to insert object in mongodb - mongodb

Question

I have a class as follows:
package mongo;
import com.mongodb.BasicDBObject;
public class tweet extends BasicDBObject{
private String name;
private Integer id;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
}
Now I am trying to insert the object of this class into mongodb:
public void connect() throws UnknownHostException
{
MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
DB db = mongoClient.getDB( "test" );
tweet t=new tweet();
t.setId(100);
t.setName("Gggggg");
DBCollection Collection = null ;
Collection = db.getCollection("test");
DBObject doc = new BasicDBObject();
doc.put("first", t);
Collection.save( doc);
System.err.println(Collection.findOne());
}
But when I run this code, the object t is not inserted to the db and the system.err.println return the following:
{ "_id" : { "$oid" : "546c00efbadcd42088c8fee3"}}
How can I add the object into mongodb? Is it possible to do that?

Answer 1

BasicDBObject is actually a LinkedHashMap. So when you extend it, you need to put and retrieve values as you do it in a map.
So simply setting the values as attributes doesn't make sense, those attributes need to be put inside the Tweet map.
You need to modify your Tweet Class as follows:
class Tweet extends BasicDBObject{
public String getName() {
return (String)this.get("name");
}
public void setName(String name) {
this.put("name", name);
}
public Integer getId() {
return (Integer)this.get("_id");
}
public void setId(Integer id) {
this.put("_id", id);
}
}
and your main method as:
MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
DB db = mongoClient.getDB( "test" );
Tweet t=new Tweet();
t.setId(100);
t.setName("Ghorbani");
DBCollection collection = null ;
collection = db.getCollection("test");
collection.save(t);
System.err.println(collection.findOne());
If you notice,collection.save(t);, the Tweet object is being directly saved. That is how it should work.
o/p:
{ "_id" : 100 , "name" : "Ghorbani"}

Answer 2

You seem to be trying to set an ID for your object. Usually that is something that is done automatically from Mongo. Try removing t.setId(100); and then run your code again.
Tip - try using Mongoose to manage your connection to Mongo.