enterprise_assest_management_app/node_api/db/connection.js

// node_api/db/connection.js
const { Pool } = require('pg');

// Create a singleton pool instance
let pool = null;

const createPool = () => {
  if (!pool) {
    pool = new Pool({
      host: process.env.DB_HOST || 'localhost',
      port: process.env.DB_PORT || 5432,
      database: process.env.DB_NAME || 'directus',
      user: process.env.DB_USER || 'directus',
      password: process.env.DB_PASSWORD || 'directus',
      max: 20, // Maximum number of connections in the pool
      idleTimeoutMillis: 30000, // Close idle connections after 30 seconds
      connectionTimeoutMillis: 2000, // Return error after 2 seconds if no connection available
    });

    // Handle pool errors
    pool.on('error', (err) => {
      console.error('Unexpected error on idle client', err);
      process.exit(-1);
    });

    console.log('📊 Database connection pool created');
  }
  
  return pool;
};

const getPool = () => {
  if (!pool) {
    createPool();
  }
  return pool;
};

const query = async (text, params) => {
  const client = await getPool().connect();
  try {
    const result = await client.query(text, params);
    return result;
  } finally {
    client.release();
  }
};

const closePool = async () => {
  if (pool) {
    await pool.end();
    pool = null;
    console.log('📊 Database connection pool closed');
  }
};

module.exports = {
  createPool,
  getPool,
  query,
  closePool
};