How to connect to Oracle DB from Node.js with `createPool()` - node.js

Question

I tried to connect oracle database to my project. I used the createpool in order to call this function in the future for all the necessary requests from the database. my config.js file:
const oracledb = require('oracledb')
oracledb.outFormat = oracledb.OUT_FORMAT_OBJECT
const init = async function (query) {
try {
await oracledb.createPool({
user: 'almat',
password: 'almat789456123',
connectString: '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=xepdb1)))'
})
console.log('Connection pool started')
await dostuff(query)
} catch (err) {
console.error('init() error: ' + err.message)
} finally {
// await closePoolAndExit()
}
}
async function dostuff (query) {
let connection
try {
connection = await oracledb.getConnection()
const sql = query
const binds = [1]
const options = { outFormat: oracledb.OUT_FORMAT_OBJECT }
const result = await connection.execute(sql, binds, options)
console.log(result)
} catch (err) {
console.error(err)
} finally {
if (connection) {
try {
await connection.close()
} catch (err) {
console.error(err)
}
}
}
}
async function closePoolAndExit () {
console.log('\nTerminating')
try {
await oracledb.getPool().close(10)
console.log('Pool closed')
process.exit(0)
} catch (err) {
console.error(err.message)
process.exit(1)
}
}
process
.once('SIGTERM', closePoolAndExit)
.once('SIGINT', closePoolAndExit)
module.exports.init = init
My app.js file:
const express = require('express');
const config = require('./utils/config');
const app = express();
app.listen(3000, function () {
console.log('Server running at port 3000')
})
app.set('view engine', 'ejs')
app.get('/', function (req, res) {
return res.render('index')
})
app.get('/login', function (req, res) {
return res.render('login')
})
app.get('/getCustomerName', function (req, res) {
const query = 'SELECT firstname FROM customer WHERE :b = 1'
const result = config.init(query)
//console.log(typeof result)
return res.send(result)
})
module.exports = app
When I request http://localhost:3000/getCustomerName it returns empty json file and terminal throws this error: NJS-047: poolAlias "default" not found in the connection pool cache

Answer 1

The createPool() call should be run once during app initialization, eg around the time you call express(). From the createPool() doc:
This method creates a pool of connections with the specified user name, password and connection string. A pool is typically created once during application initialization.
init() shouldn't call doStuff(). Once the pool is created, then your web listener handlers can call dostuff().
Look at the basic example webapp.js.
Also see the Oracle Magazine series Build REST APIs for Node.js which has source code here.