Database integration

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
• Couchbase
• CouchDB
• LevelDB
• MySQL
• MongoDB
• Neo4j
• Oracle
• PostgreSQL
• Redis
• SQL Server
• SQLite
• Elasticsearch

Caution

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

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

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

Couchbase

Module: couchnode

Installation

npm install couchbase

Example

const couchbase = require("couchbase");
const bucket = new couchbase.Cluster("http://localhost:8091").openBucket(
  "bucketName"
);

// add a document to a bucket
bucket.insert("document-key", { name: "Matt", shoeSize: 13 }, (err, result) => {
  if (err) {
    console.log(err);
  } else {
    console.log(result);
  }
});

// get all documents with shoe size 13
const n1ql = "SELECT d.* FROM `bucketName` d WHERE shoeSize = $1";
const query = N1qlQuery.fromString(n1ql);
bucket.query(query, [13], (err, result) => {
  if (err) {
    console.log(err);
  } else {
    console.log(result);
  }
});

CouchDB

Module: nano

Installation

npm install nano

Example

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

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

// Get a list of all books
books.list((err, body) => {
  if (err) {
    console.log(err);
  } else {
    console.log(body.rows);
  }
});

LevelDB

Module: levelup

Installation

npm install level levelup leveldown

Example

const levelup = require("levelup");
const db = levelup("./mydb");

db.put("name", "LevelUP", (err) => {
  if (err) return console.log("Ooops!", err);

  db.get("name", (err, value) => {
    if (err) return console.log("Ooops!", err);

    console.log(`name=${value}`);
  });
});

MySQL

Module: mysql

Installation

npm install mysql

Example

const mysql = require("mysql");
const connection = mysql.createConnection({
  host: "localhost",
  user: "dbuser",
  password: "s3kreee7",
  database: "my_db"
});

connection.connect();

connection.query("SELECT 1 + 1 AS solution", (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 (v2.*)

const MongoClient = require("mongodb").MongoClient;

MongoClient.connect("mongodb://localhost:27017/animals", (err, db) => {
  if (err) throw err;

  db.collection("mammals")
    .find()
    .toArray((err, result) => {
      if (err) throw err;

      console.log(result);
    });
});

Example (v3.*)

const MongoClient = require("mongodb").MongoClient;

MongoClient.connect("mongodb://localhost:27017/animals", (err, client) => {
  if (err) throw err;

  const db = client.db("animals");

  db.collection("mammals")
    .find()
    .toArray((err, result) => {
      if (err) throw err;

      console.log(result);
    });
});

If you want an object model driver for MongoDB, look at Mongoose.

Neo4j

Module: neo4j-driver

Installation

npm install neo4j-driver

Example

const neo4j = require("neo4j-driver");
const driver = neo4j.driver(
  "neo4j://localhost:7687",
  neo4j.auth.basic("neo4j", "letmein")
);

const session = driver.session();

session.readTransaction((tx) => {
  return tx
    .run("MATCH (n) RETURN count(n) AS count")
    .then((res) => {
      console.log(res.records[0].get("count"));
    })
    .catch((error) => {
      console.log(error);
    });
});

Oracle

Module: oracledb

Installation

NOTE: See installation prerequisites.

npm install oracledb

Example

const oracledb = require("oracledb");
const config = {
  user: "<your db user>",
  password: "<your db password>",
  connectString: "localhost:1521/orcl"
};

async function getEmployee(empId) {
  let conn;

  try {
    conn = await oracledb.getConnection(config);

    const result = await conn.execute(
      "select * from employees where employee_id = :id",
      [empId]
    );

    console.log(result.rows[0]);
  } catch (err) {
    console.log("Ouch!", err);
  } finally {
    if (conn) {
      // conn assignment worked, need to close
      await conn.close();
    }
  }
}

getEmployee(101);

PostgreSQL

Module: pg-promise

Installation

npm install pg-promise

Example

const pgp = require("pg-promise")(/* options */);
const db = pgp("postgres://username:password@host:port/database");

db.one("SELECT $1 AS value", 123)
  .then((data) => {
    console.log("DATA:", data.value);
  })
  .catch((error) => {
    console.log("ERROR:", error);
  });

Redis

Module: redis

Installation

npm install redis

Example

const redis = require("redis");
const client = redis.createClient();

client.on("error", (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", (err, replies) => {
  console.log(`${replies.length} replies:`);

  replies.forEach((reply, i) => {
    console.log(`    ${i}: ${reply}`);
  });

  client.quit();
});

SQL Server

Module: tedious

Installation

npm install tedious

Example

const Connection = require("tedious").Connection;
const Request = require("tedious").Request;

const config = {
  server: "localhost",
  authentication: {
    type: "default",
    options: {
      userName: "your_username", // update me
      password: "your_password" // update me
    }
  }
};

const connection = new Connection(config);

connection.on("connect", (err) => {
  if (err) {
    console.log(err);
  } else {
    executeStatement();
  }
});

function executeStatement() {
  request = new Request("select 123, 'hello world'", (err, rowCount) => {
    if (err) {
      console.log(err);
    } else {
      console.log(`${rowCount} rows`);
    }
    connection.close();
  });

  request.on("row", (columns) => {
    columns.forEach((column) => {
      if (column.value === null) {
        console.log("NULL");
      } else {
        console.log(column.value);
      }
    });
  });

  connection.execSql(request);
}

SQLite

Module: sqlite3

Installation

npm install sqlite3

Example

const sqlite3 = require("sqlite3").verbose();
const db = new sqlite3.Database(":memory:");

db.serialize(() => {
  db.run("CREATE TABLE lorem (info TEXT)");
  const stmt = db.prepare("INSERT INTO lorem VALUES (?)");

  for (let i = 0; i < 10; i++) {
    stmt.run(`Ipsum ${i}`);
  }

  stmt.finalize();

  db.each("SELECT rowid AS id, info FROM lorem", (err, row) => {
    console.log(`${row.id}: ${row.info}`);
  });
});

db.close();

Elasticsearch

Module: elasticsearch

Installation

npm install elasticsearch

Example

const elasticsearch = require("elasticsearch");
const client = elasticsearch.Client({
  host: "localhost:9200"
});

client
  .search({
    index: "books",
    type: "book",
    body: {
      query: {
        multi_match: {
          query: "express js",
          fields: ["title", "description"]
        }
      }
    }
  })
  .then(
    (response) => {
      const hits = response.hits.hits;
    },
    (error) => {
      console.trace(error.message);
    }
  );