Database integration

Adding database connectivity capability to Express apps is just a matter of loading an appropriate Node.js driver for the database in your app. This document briefly explains how to add and use some of the most popular Node modules for database systems in your Express app:

• Cassandra
• CouchDB
• LevelDB
• MySQL
• MongoDB
• Neo4j
• PostgreSQL
• Redis
• SQLite

Cassandra

Module: cassandra-driver Installation

$ npm install cassandra-driver

Example

var cassandra = require('cassandra-driver');
var client = new cassandra.Client({ contactPoints: ['localhost']});

client.execute('select key from system.local', function(err, result) {
  if (err) throw err;
  console.log(result.rows[0]);
});

CouchDB

Module: nano Installation

$ npm install nano

Example

var nano = require('nano')('http://localhost:5984');
nano.db.create('books');
var books = nano.db.use('books');

//Insert a book document in the books database
books.insert({name: 'The Art of war'}, null, function(err, body) {
  if (!err){
    console.log(body);
  }
});

//Get a list of all books
books.list(function(err, body){
  console.log(body.rows);
});

LevelDB

Module: levelup Installation

$ npm install level

Example

var levelup = require('levelup');
var db = levelup('./mydb');

db.put('name', 'LevelUP', function (err) {

  if (err) return console.log('Ooops!', err);
  db.get('name', function (err, value) {
    if (err) return console.log('Ooops!', err);
    console.log('name=' + value);
  });

});

MySQL

Module: mysql Installation

$ npm install mysql

Example

var mysql      = require('mysql');
var connection = mysql.createConnection({
  host     : 'localhost',
  user     : 'dbuser',
  password : 's3kreee7'
});

connection.connect();

connection.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
  if (err) throw err;
  console.log('The solution is: ', rows[0].solution);
});

connection.end();

MongoDB

Module: mongoskin Installation

$ npm install mongoskin

Example

var db = require('mongoskin').db('localhost:27017/animals');

db.collection('mamals').find().toArray(function(err, result) {
  if (err) throw err;
  console.log(result);
});

If you want a object model driver for MongoDB, checkout Mongoose.

Neo4j

Module: apoc Installation

$ npm install apoc

Example

var apoc = require('apoc');

apoc.query('match (n) return n').exec().then(
  function (response) {
    console.log(response);
  },
  function (fail) {
    console.log(fail);
  }
);

PostgreSQL

Module: pg Installation

$ npm install pg

Example

var pg = require('pg');
var conString = "postgres://username:password@localhost/database";

pg.connect(conString, function(err, client, done) {

  if (err) {
    return console.error('error fetching client from pool', err);
  }
  client.query('SELECT $1::int AS number', ['1'], function(err, result) {
    done();
    if (err) {
      return console.error('error running query', err);
    }
    console.log(result.rows[0].number);
  });

});

Redis

Module: redis Installation

$ npm install redis

Example

var client = require('redis').createClient();

client.on('error', function (err) {
  console.log('Error ' + err);
});

client.set('string key', 'string val', redis.print);
client.hset('hash key', 'hashtest 1', 'some value', redis.print);
client.hset(['hash key', 'hashtest 2', 'some other value'], redis.print);

client.hkeys('hash key', function (err, replies) {

  console.log(replies.length + ' replies:');
  replies.forEach(function (reply, i) {
    console.log('    ' + i + ': ' + reply);
  });

  client.quit();

});

SQLite

Module: sqlite3 Installation

$ npm install sqlite3

Example

var sqlite3 = require('sqlite3').verbose();
var db = new sqlite3.Database(':memory:');

db.serialize(function() {

  db.run('CREATE TABLE lorem (info TEXT)');
  var stmt = db.prepare('INSERT INTO lorem VALUES (?)');

  for (var i = 0; i < 10; i++) {
    stmt.run('Ipsum ' + i);
  }

  stmt.finalize();

  db.each('SELECT rowid AS id, info FROM lorem', function(err, row) {
    console.log(row.id + ': ' + row.info);
  });
});

db.close();