Adding the capability to connect databases 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.js modules for database systems in your Express app:
- Cassandra
- CouchDB
- LevelDB
- MySQL
- MongoDB
- Neo4j
- PostgreSQL
- Redis
- SQLite
- ElasticSearch
These database drivers are among many that are available. For other options, search on the npm site.
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 levelup leveldown
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: mongodb Installation
$ npm install mongodb
Example
var MongoClient = require('mongodb').MongoClient; MongoClient.connect('mongodb://localhost:27017/animals', function(err, db) { if (err) { throw err; } db.collection('mammals').find().toArray(function(err, result) { if (err) { throw err; } console.log(result); }); });
If you want an object model driver for MongoDB, look at 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-promise Installation
$ npm install pg-promise
Example
var pgp = require("pg-promise")(/*options*/); var db = pgp("postgres://username:password@host:port/database"); db.one("SELECT $1 AS value", 123) .then(function (data) { console.log("DATA:", data.value); }) .catch(function (error) { console.log("ERROR:", error); });
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();
ElasticSearch
Module: elasticsearch Installation
$ npm install elasticsearch
Example
var elasticsearch = require('elasticsearch'); var client = elasticsearch.Client({ host: 'localhost:9200' }); client.search({ index: 'books', type: 'book', body: { query: { multi_match: { query: 'express js', fields: ['title', 'description'] } } } }).then(function(response) { var hits = response.hits.hits; }, function(error) { console.trace(error.message); });
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