Mongodb – can‚Äôt login via -u root -p bitnami

Are you trying to login like this?

mongo admin --username root --password YOUR_PASSWORD

where YOUR_PASSWORD is the one you can see in your AWS system log:

Setting Bitnami application password to 'YOUR_PASSWORD'

If this doesn’t work, you can also try resetting MongoDB password:

MongoDb : Case in-sensative search using pymongo

As we all know Json is case sensitive and so is MongoDB, hence searching same name which got save in different case might not return any result. The solution is to do case in-sensative search.

Below is the example of pymongo

db.users.find_one({'name': re.compile(username, re.IGNORECASE)})

MongoDB : Java program to do basic crud operation

Sample Java program to connect MongoDb and perform Crud Operations.

Copy paste, run and learn ūüėČ

note :- Please ensure you have installed mongo dependency using jar, github or mvn


package com.premaseem.core;

import com.mongodb.*;

import java.util.Date;

 * Java + MongoDB Crud operation example
public class App {
    public static void main(String[] args) {

        try {

            /**** Connect to MongoDB ****/
            // Since 2.10.0, uses MongoClient
            MongoClient mongo = new MongoClient("localhost", 27017);

            // or, to connect to a replica set, with auto-discovery of the primary, supply a seed list of members
//            MongoClient mongoClient = new MongoClient(Arrays.asList(new ServerAddress("localhost", 27017),
//                    new ServerAddress("localhost", 27018),
//                    new ServerAddress("localhost", 27019)));

            /**** Get database ****/
            // if database doesn't exists, MongoDB will create it for you
            DB db = mongo.getDB("testdb");

            /**** Get collection / table from 'testdb' ****/
            // if collection doesn't exists, MongoDB will create it for you
            DBCollection table = db.getCollection("user");

            /**** Insert ****/
            // create a document to store key and value
            BasicDBObject document = new BasicDBObject();
            document.put("name", "premaseem");
            document.put("age", 30);
            document.put("createdDate", new Date());

            /**** Find and display ****/
            BasicDBObject searchQuery = new BasicDBObject();
            searchQuery.put("name", "premaseem");

            DBCursor cursor = table.find(searchQuery);

            while (cursor.hasNext()) {

            /**** Update ****/
            // search document where name="premaseem" and update it with new values
            BasicDBObject query = new BasicDBObject();
            query.put("name", "premaseem");

            BasicDBObject newDocument = new BasicDBObject();
            newDocument.put("name", "premaseem-updated");

            BasicDBObject updateObj = new BasicDBObject();
            updateObj.put("$set", newDocument);

            table.update(query, updateObj);

            /**** Find and display ****/
            BasicDBObject searchQuery2
                    = new BasicDBObject().append("name", "premaseem-updated");

            DBCursor cursor2 = table.find(searchQuery2);

            while (cursor2.hasNext()) {

            /**** Done ****/

        }  catch (MongoException e) {


MongoDB : Exporting JSON with mongoexport

This will export a JSON representation of the database. Note that as a rule – particularly for backing up or moving data – MongoDB recommends the “dump and restore” approach as BSON can contain more rich data than JSON. Nevertheless, mongoexport still has its uses, sometimes a JSON representation of the data is very useful – it’s what we’ve been using so far in the application development.

Basic output to console

Need to specify the name of the database –db and the collection –collection to export. Restoring dumped data with MongoRestore Inserts only, no updates Exporting JSON with mongoexport

Basic output to console

> mongoexport –db meantest –collection tech

Send to a file

> mongoexport –db meantest –collection tech –out MEAN/api/data/tech.json

Create as array

> mongoexport –db meantest –collection tech –out MEAN/api/data/tech.json –jsonArray

Make output pretty

> mongoexport –db meantest –collection tech –out MEAN/api/data/tech.json –jsonArray –pretty


MongoDB : How to take export a database using mongo dump

We need to take database backup or have to export specific database in  mongo

This command will export specific databases in mongo and export to home folder /dump

> mongodump –db testDatabase

# to compress in zip file and folder

> mongodump –db testDatabase ¬† –gzip

cd ~/dump



This command will restore or import specific db

>mongorestore –db testDatabase ¬† –gzip ¬†~/dump/testDatabase


With auth you can take dump as

mongodump -h¬†-p 27017 -d dbName -u “user” -p “password” –excludeCollectionsWithPrefix=system

and restore as

mongorestore -d dbName¬†–dir=dbDir

Note :

There command should be run from command prompt / shell and not from mongo sheel.

Mongo restroe does not update existing collections

MongoDB : Normalize Database reference (DBRefs)

The joy of a Document database is that it eliminates lots of Joins. Your first instinct should be to place as much in a single document as you can. Because MongoDB documents have structure, and because you can efficiently query within that structure there is no immediate need to normalize data like you would in SQL. In particular any data that is not useful apart from its parent document should be part of the same document.

This is not so much a “storage space” issue as it is a “data consistency” issue. If many records will refer to the same data it is more efficient and less error prone to update a single record and keep references to it in other places.

DBRef documents resemble the following document:

{ "$ref" : <value>, "$id" : <value>, "$db" : <value> }

Consider a document from a collection that stored a DBRef in a creator field:

  "_id" : ObjectId("5126bbf64aed4daf9e2ab771"),
  // .. application fields
  "creator" : {
                  "$ref" : "creators",
                  "$id" : ObjectId("5126bc054aed4daf9e2ab772"),
                  "$db" : "users"

The DBRef in this example points to a document in the creators collection of the users database that has ObjectId("5126bc054aed4daf9e2ab772") in its _id field.

Consider the following operation to insert two documents, using the _id field of the first document as a reference in the second document:

original_id = ObjectId()

    "_id": original_id,
    "name": "Broadway Center",
    "url": ""

    "name": "Erin",
    "places_id": original_id,
    "url":  ""

Then, when a query returns the document from the people collection you can, if needed, make a second query for the document referenced by the places_id field in the places collection.

Reference link for details :