A simple example about how to connect to a PostgreSQL database using Node.js
Let’s create a folder to host our example. Open a terminal and type:
mkdir node-js-postgresql
Enter to the folder
cd node-js-postgresql
Use package.json generator. Follow the steps
npm init
npm install
Install pg module in our project
npm install pg --save
In case you have a database url connection you will have to parse it. There’s a module to parse such as url. Example url:
postgres://hfbwxykfdgkurg:a75568307daad4b1432b5d173719ba7ba908ea06e7d0ebe8bf7bd434eb655547@ec2-108-21-167-137.compute-1.amazonaws.com:5432/w5tftigeor6odh
Install the module
npm install parse-database-url --save
Create a file called db_helper.js
const parseDbUrl = require("parse-database-url");
//we have our connection url in an environment config variable. Each developer will have his own
//a connection url will look like this:
//postgres://hfbwxykfdgkurg:a75568307daad4b1432b5d173719ba7ba908ea06e7d0ebe8bf7bd434eb655547@ec2-108-21-167-137.compute-1.amazonaws.com:5432/w5tftigeor6odh
const dbConfig = parseDbUrl(process.env.DATABASE_URL);
const Pool = require("pg").Pool;
const pool = new Pool({
user: dbConfig.user,
host: dbConfig.host,
database: dbConfig.database,
password: dbConfig.password,
port: dbConfig.port,
ssl: true,
});
module.exports.execute = pool;
In the line number 6 we have a call to a configuration environment variable
process.env.DATABASE_URL
It’s a good way to avoid versioning sensitive data like a database connection or other credentials. To run this example you can just hard-code it
Create a file called index.js
const dbHelper = require("./db_helper");
//deal with the promise
findUserById(1234)
.then(user => {
console.info(user);
})
.catch(error => {
console.error(error);
});
/**
*
* @param userId
* @returns a Promise with the user row for the given id
* @throws error if there's a connection issue or if the user was not found by the id
*/
async function findUserById(userId) {
const query = "SELECT * FROM users WHERE id = $1 LIMIT 1";
const bindings = [userId];
const result = await dbHelper.execute.query(query, bindings);
if (result.rows.length > 0) {
return result.rows[0];
} else {
throw Error("User not found by id " + userId);
}
}
Run the example
node index.js
That’s it 🙂
Full source code:
https://github.com/andrescanavesi/node-js-postgresql
