BE THE CODER > No SQL > Mongo DB Examples > How to Save or Update Document

MongoDB is a scalable, high-performance, open source NoSQL database. It offers Ad hoc queries, Indexing, Replication, Load balancing, File storage (GridFS), Aggregation, MapReduce and Server-side JavaScript execution. This requires the library mongo-2.8.0.jar to be present in the classpath. The following example shows how to save or update a document in Mongo database.

File Name :	com/bethecoder/tutorials/mongodb/tests/SaveOrUpdateCollectionTest.java
Author :	Sudhakar KV
Email :	[email protected]


package com.bethecoder.tutorials.mongodb.tests;



import java.net.UnknownHostException;



import com.mongodb.BasicDBObject;

import com.mongodb.DB;

import com.mongodb.DBCollection;

import com.mongodb.DBCursor;

import com.mongodb.DBObject;

import com.mongodb.Mongo;

import com.mongodb.MongoException;



public class SaveOrUpdateCollectionTest {



  /**

   * @param args

   */

  public static void main(String[] args) {



    try {

      //Connect to mongoDB with given IP and PORT

      Mongo mongo = new Mongo("localhost", 27017);

      

      //Get the database object

      DB database = mongo.getDB("mytestdb");

      

      //Gets a collection with a given name.

        //If the collection does not exist, a new collection is created.

      DBCollection collection = database.getCollection("students");

      collection.drop();

      

      //List collection before update

      System.out.println("--- Before Update ---");

      listAll(collection);

      

      System.out.println("--- After First Update ---");



      //Update the old document with new document

      DBObject query = new BasicDBObject().append("name", "Sudhakar");

      DBObject newDocument = new BasicDBObject();

      newDocument.put("name", "Sudhakar");

      newDocument.put("mobile", "987654321");

      

      //This method creates a new document if it doesn't exist

      collection.update(query, newDocument, true, false);

      listAll(collection);

      

      System.out.println("--- After Second Update ---");

      newDocument = new BasicDBObject();

      newDocument.put("name", "Sudhakar");

      newDocument.put("mobile", "100000001");

      

      //This method creates a new document if it doesn't exist

      collection.update(query, newDocument, true, false);

      listAll(collection);

      

    } catch (UnknownHostException e) {

      e.printStackTrace();

    } catch (MongoException e) {

      e.printStackTrace();

    }

  }

  

  private static void listAll(DBCollection collection) {

    //Queries for all objects in this collection

    DBCursor dbCursor = collection.find();

    DBObject record = null;

    

    while (dbCursor.hasNext()) {

      record = dbCursor.next();

      System.out.println(record);

    }

  }

}