Database integration in Express

Database integration in Express.js

Let us look at how we can integrate a database in a server working upon the Express.js framework. The steps can be divided as creating the application, running the server and finally integrating the database.

Step 1: Create an Express Application 

Here we will create an Express application because all of our work will be going to execute inside Express. 

Running the following command in your terminal gets you to start a node app and install Express.

npm init
npm install express

 

Now create an empty .js file (let’s name it Ninja.js).

This is how your folder would look like now.

Folder structure

 

Now let's write Express code in our Ninja.js file.

Code:

// Importing the express module
const express = require('express');
const app = express();
const port = 3000;
app.listen(port, (error) =>{
if(!error)
console.log("Server is Running "
+ "| App listening on port: "+ port)
else
console.log("Error occurred, cannot start the server", error);
}
);

 

Step 2: Running the server

Now run the server by giving the following command in your terminal.

 

Command:

node Ninja.js

 

 

Output

Step 3: Integrating with database

There are a lot of databases available to integrate with Express. The choice depends on the requirements of the project you are working on. For now, let us choose MySQL and see how we can integrate it with Express.

Integrating with a database can be divided into 3 steps.

Step 1: Downloading MySQL driver for the Express application

Run the following command to download the driver.

npm install mysql

 

Step 2: Installing MySQL locally

To use MySQL, you should have it downloaded locally. You can visit their official website to download them. 

Step 3: Integrating with Express

For this, edit the Ninja.js file and insert the following code.

Code:

// Importing the express module
const express = require('express');
const app = express();
const port = 3000;

// Create a connection to the database
const mysql = require('mysql');
const PORT = 4000;
const connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: '',
database: "test" 
});
// Open the MySQL connection
connection.connect(error => {
if (error){
console.log("A error has been occurred "
+ "while connecting to database."); 
throw error;
}
// If Everything goes correct, Then start Express Server
app.listen(PORT, ()=>{
console.log("Database connection is Ready and "
+ "Server is Listening on Port ", PORT);
})
});

 

Save the file. Start your web server and once again run the following command.

node Ninja.js

 

If there are no errors present, then you should get the following output..

Output

Integrating with popular databases

Database integration in Express refers to connecting Express with databases like MySQL, MongoDB, Cassandra etc. It is quite easy to do database integration in Express as we only have to load the appropriate Node.js drivers of the database in our application. Let us see how we can install drivers of various databases to do database integration in Express and example codes for the same.

MongoDB

MongoDB is a source-available cross-platform document-oriented database program. It uses JSON-like documents.

Installation:

$ npm install mongodb

 

Example:

const MongoClient = require('mongodb').MongoClient
const url = 'mongodb://127.0.0.1:27017'
const dbName = 'CodingNinjas'

const db

MongoClient.connect(url, { useNewUrlParser: true }, (err, client) => {
 if (err) return console.log(err)

 // Storing a reference to the database so you can use it later
 db = client.db(dbName)
 console.log(`Connected MongoDB: ${url}`)
 console.log(`Database: ${dbName}`)
})

PostgreSQL

PostgreSQL is a free and open-source relational database management system focusing on extensibility and SQL compliance.

Installation:

$ npm install pg-promise

Example:

var pg = require('pg');
var conString = "postgres://YourUserName:YourPassword@localhost:5432/YourDatabase";
var client = new pg.Client(conString);
client.connect();

Cassandra

Apache Cassandra is a free and open-source, NoSQL database management system designed to handle very large amounts of data.

Installation:

$ npm install cassandra-driver

Example:

var cassandraDB = require('cassandra-driver')
var client = new cassandraDB.Client({ contactPoints: ['localhost'] })
client.execute('select key from system.local', function (err, result) {
 if (err) throw err
 console.log(result.rows[0])
})

Elasticsearch

Elasticsearch is a search engine based on the Lucene library. 

Installation:

$ npm install elasticsearch

Example:

var ES = require('elasticsearch')
var client = ES.Client({
 host: 'localhost:9200'
})

SQLite

SQLite is a relational database management system contained in a C library.

Installation:

$ npm install sqlite3

Example:

var SQLite3 = require('sqlite3').verbose()
var db = new SQLite3.Database(':memory:')
// Enter your code here
// Close connection after use
db.close()

SQL Server

Microsoft SQL Server is a relational database management system made by Microsoft.

Installation:

$ npm install tedious

 

Example:

var Connection = require('tedious').Connection
var Request = require('tedious').Request
var config = {
 server: 'localhost',
 authentication: {
   type: 'default',
   options: {
     userName: 'username', // Update this value
     password: 'pwd' // Update this value
   }
 }
}
var connection = new Connection(config)

Redis

Redis is an in-memory database that persists on a disk. 

Installation:

$ npm install redis

 

Example:

var redis = require('redis')
var client = redis.createClient()
client.on('error', function (err) {
 console.log('Error ' + err)
})
// Enter your code here

// Close connection after use
client.quit()

Oracle

Oracle Database is a multi-model database management system produced and marketed by Oracle Corporation.

Installation:

$ npm install oracledb

 

Example:

const oracleDatabase = require('oracledb')
const config = {
 user: 'your-username',
 password: 'your-password',
 connectString: 'localhost:1521/orcl'
}

// Create connection
connection = oracledb.getConnection(config)

// Close connection
connection.close()

Neo4j

Neo4j is a graph database management system. It was developed by Neo4j, Inc.

Installation:

$ npm install neo4j-driver

 

Example:

var neo4j = require('neo4j-driver')
var driver = neo4j.driver('neo4j://localhost:7687', neo4j.auth.basic('neo4j', 'letmein'))
var session = driver.session()

LevelDB

LevelDB is an open-source on-disk key-value store.

Installation:

$ npm install level levelup leveldown

 

Example:

var levelup = require('levelup')
var database = levelup('./mydb')

CouchDB

Apache CouchDB is an open-source document-oriented NoSQL database.

Installation:

$ npm install nano

 

Example:

var couch = require('nano')('http://localhost:5984')
// Creating a database named books
couch.db.create('books')
var books = couch.db.use('books')

Couchbase

Couchbase is an open-source, distributed multi-model NoSQL document-oriented database.

Installation:

$ npm install couchbase

 

Example:

var couchbase = require('couchbase')
var bucket = (new couchbase.Cluster('http://localhost:8091')).openBucket('bucketName')

Frequently Asked Questions

How can I do database integration in Express?

It is easy to do database integration in Express. You only have to load the appropriate Node.js drivers of the database in your application.

2. Can I use some other package managers other than npm to install the drivers?

Yes, you can use other package managers. Yarn is one popular choice after npm. 

Key Takeaways

We have looked into Database integration in Express and understood that it refers to connecting Express with databases like MySQL, MongoDB, Cassandra, etc. We also saw that It is quite easy to do database integration in Express as we only have to load the appropriate Node.js drivers of the database in our application. 

If you enjoyed reading this article about Database integration in Express, check out Free JavaScript Tutorial By Coding Ninjas and 10 Best JavaScript Certifications In 2021.