mongodb-core

What is mongodb-core?

The mongodb-core package is a low-level driver for MongoDB that provides the core functionality for interacting with MongoDB databases. It is used internally by the higher-level mongodb package but can be used directly for more fine-grained control over MongoDB operations.

What are mongodb-core's main functionalities?

Connecting to MongoDB

This feature allows you to establish a connection to a MongoDB server. The code sample demonstrates how to create a new MongoClient instance and connect to a MongoDB server running on localhost.

const MongoClient = require('mongodb-core').MongoClient;
const client = new MongoClient('mongodb://localhost:27017');
client.connect((err) => {
  if (err) throw err;
  console.log('Connected to MongoDB');
  client.close();
});

Performing CRUD Operations

This feature allows you to perform CRUD (Create, Read, Update, Delete) operations on a MongoDB database. The code sample demonstrates how to insert a document into a collection.

const MongoClient = require('mongodb-core').MongoClient;
const client = new MongoClient('mongodb://localhost:27017');
client.connect((err) => {
  if (err) throw err;
  const db = client.db('test');
  const collection = db.collection('documents');
  collection.insertOne({ a: 1 }, (err, result) => {
    if (err) throw err;
    console.log('Document inserted');
    client.close();
  });
});

Handling Replication

This feature allows you to handle MongoDB replication. The code sample demonstrates how to connect to a MongoDB replica set.

const ReplSet = require('mongodb-core').ReplSet;
const replSet = new ReplSet([{ host: 'localhost', port: 27017 }], { setName: 'rs0' });
replSet.on('connect', () => {
  console.log('Connected to replica set');
  replSet.destroy();
});
replSet.connect();

Other packages similar to mongodb-core

mongodb

The mongodb package is a higher-level driver for MongoDB that builds on top of mongodb-core. It provides a more user-friendly API and additional features such as connection pooling, schema validation, and more. It is the recommended package for most users.

mongoose

Mongoose is an Object Data Modeling (ODM) library for MongoDB and Node.js. It provides a higher-level abstraction over the MongoDB driver, including schema-based data validation, middleware, and more. It is ideal for applications that require a structured data model.

monk

Monk is a minimalistic wrapper around the MongoDB driver that provides a simple and easy-to-use API for interacting with MongoDB. It is less feature-rich than mongoose but offers a more straightforward approach for basic CRUD operations.

README

Description

The MongoDB Core driver is the low level part of the 2.0 or higher MongoDB driver and is meant for library developers not end users. It does not contain any abstractions or helpers outside of the basic management of MongoDB topology connections, CRUD operations and authentication.

MongoDB Node.JS Core Driver

what	where
documentation	http://mongodb.github.io/node-mongodb-native/
apidoc	http://mongodb.github.io/node-mongodb-native/
source	https://github.com/mongodb-js/mongodb-core
mongodb	http://www.mongodb.org/

Blogs of Engineers involved in the driver

• Christian Kvalheim @christkv http://christiankvalheim.com

Bugs / Feature Requests

Think you’ve found a bug? Want to see a new feature in node-mongodb-native? Please open a case in our issue management tool, JIRA:

• Create an account and login https://jira.mongodb.org.
• Navigate to the NODE project https://jira.mongodb.org/browse/NODE.
• Click Create Issue - Please provide as much information as possible about the issue type and how to reproduce it.

Bug reports in JIRA for all driver projects (i.e. NODE, PYTHON, CSHARP, JAVA) and the Core Server (i.e. SERVER) project are public.

Questions and Bug Reports

• mailing list: https://groups.google.com/forum/#!forum/node-mongodb-native
• jira: http://jira.mongodb.org/

Change Log

http://jira.mongodb.org/browse/NODE

QuickStart

The quick start guide will show you how to set up a simple application using Core driver and MongoDB. It scope is only how to set up the driver and perform the simple crud operations. For more inn depth coverage we encourage reading the tutorials.

Create the package.json file

Let's create a directory where our application will live. In our case we will put this under our projects directory.

mkdir myproject
cd myproject

Create a package.json using your favorite text editor and fill it in.

{
  "name": "myproject",
  "version": "1.0.0",
  "description": "My first project",
  "main": "index.js",
  "repository": {
    "type": "git",
    "url": "git://github.com/christkv/myfirstproject.git"
  },
  "dependencies": {
    "mongodb-core": "~1.0"
  },
  "author": "Christian Kvalheim",
  "license": "Apache 2.0",
  "bugs": {
    "url": "https://github.com/christkv/myfirstproject/issues"
  },
  "homepage": "https://github.com/christkv/myfirstproject"
}

Save the file and return to the shell or command prompt and use NPM to install all the dependencies.

npm install

You should see NPM download a lot of files. Once it's done you'll find all the downloaded packages under the node_modules directory.

Booting up a MongoDB Server

Let's boot up a MongoDB server instance. Download the right MongoDB version from MongoDB, open a new shell or command line and ensure the mongod command is in the shell or command line path. Now let's create a database directory (in our case under /data).

mongod --dbpath=/data --port 27017

You should see the mongod process start up and print some status information.

Connecting to MongoDB

Let's create a new app.js file that we will use to show the basic CRUD operations using the MongoDB driver.

First let's add code to connect to the server. Notice that there is no concept of a database here and we use the topology directly to perform the connection.

var Server = require('mongodb-core').Server
  , assert = require('assert');

// Set up server connection
var server = new Server({
    host: 'localhost'
  , port: 27017
  , reconnect: true
  , reconnectInterval: 50
});

// Add event listeners
server.on('connect', function(_server) {
  console.log('connected');
  test.done();
});

server.on('close', function() {
  console.log('closed');
});

server.on('reconnect', function() {
  console.log('reconnect');
});

// Start connection
server.connect();

To connect to a replicaset we would use the ReplSet class and for a set of Mongos proxies we use the Mongos class. Each topology class offer the same CRUD operations and you operate on the topology directly. Let's look at an example exercising all the different available CRUD operations.

var Server = require('mongodb-core').Server
  , assert = require('assert');

// Set up server connection
var server = new Server({
    host: 'localhost'
  , port: 27017
  , reconnect: true
  , reconnectInterval: 50
});

// Add event listeners
server.on('connect', function(_server) {
  console.log('connected');

  // Execute the ismaster command
  _server.command('system.$cmd', {ismaster: true}, function(err, result) {

    // Perform a document insert
    _server.insert('myproject.inserts1', [{a:1}, {a:2}], {
      writeConcern: {w:1}, ordered:true
    }, function(err, results) {
      assert.equal(null, err);
      assert.equal(2, results.result.n);      

      // Perform a document update
      _server.update('myproject.inserts1', [{
        q: {a: 1}, u: {'$set': {b:1}}
      }], {
        writeConcern: {w:1}, ordered:true
      }, function(err, results) {
        assert.equal(null, err);
        assert.equal(1, results.result.n);

        // Remove a document
        _server.remove('myproject.inserts1', [{
          q: {a: 1}, limit: 1
        }], {
          writeConcern: {w:1}, ordered:true
        }, function(err, results) {
          assert.equal(null, err);
          assert.equal(1, results.result.n);

          // Get a document
          var cursor = _server.cursor('integration_tests.inserts_example4', {
              find: 'integration_tests.example4'
            , query: {a:1}
          });

          // Get the first document
          cursor.next(function(err, doc) {
            assert.equal(null, err);
            assert.equal(2, doc.a);

            // Execute the ismaster command
            _server.command("system.$cmd"
              , {ismaster: true}, function(err, result) {
                assert.equal(null, err)
                _server.destroy();              
            });
          });
      });
    });

    test.done();
  });
});

server.on('close', function() {
  console.log('closed');
});

server.on('reconnect', function() {
  console.log('reconnect');
});

// Start connection
server.connect();

The core driver does not contain any helpers or abstractions only the core crud operations. These consist of the following commands.

• insert, Insert takes an array of 1 or more documents to be inserted against the topology and allows you to specify a write concern and if you wish to execute the inserts in order or out of order.
• update, Update takes an array of 1 or more update commands to be executed against the server topology and also allows you to specify a write concern and if you wish to execute the updates in order or out of order.
• remove, Remove takes an array of 1 or more remove commands to be executed against the server topology and also allows you to specify a write concern and if you wish to execute the removes in order or out of order.
• cursor, Returns you a cursor for either the 'virtual' find command, a command that returns a cursor id or a plain cursor id. Read the cursor tutorial for more inn depth coverage.
• command, Executes a command against MongoDB and returns the result.
• auth, Authenticates the current topology using a supported authentication scheme.

The Core Driver is a building block for library builders and is not meant for usage by end users as it lacks a lot of features the end user might need such as automatic buffering of operations when a primary is changing in a replicaset or the db and collections abstraction.

Next steps

The next step is to get more in depth information about how the different aspects of the core driver works and how to leverage them to extend the functionality of the cursors. Please view the tutorials for more detailed information.