Async/Await in NodeJs and MySql connection - mysql

Question

I've two problems.
Async/Await in queries
Env variables in pool config
I use TypeScript with Node.js and Express and I install promise-mysql but I would not refuse the use of myslq or mysql2. Currently this is my code:
database.ts
import mysql, { PoolConfig } from 'promise-mysql';
import keys from './keys';
const pool = startConnection();
export default pool;
// Functions
function startConnection() {
const pool = mysql.createPool(dbOptions(true));
pool.get('getConnection').then(async () => {
await (await pool).releaseConnection;
console.log('DB is connected.');
});
return pool;
}
function dbOptions(dev: boolean): PoolConfig {
var dbInfo: PoolConfig;
if (dev) {
dbInfo = {
database: process.env.DB || keys.DB.DB,
host: process.env.DB_HOST || keys.DB.DB_HOST,
user: process.env.DB_USER || keys.DB.DB_USER,
password: process.env.DB_U_PASS || keys.DB.DB_U_PASS
};
} else {
dbInfo = {
database: process.env.DB,
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_U_PASS
};
}
return dbInfo;
}
And a query looks like this:
import pool from 'database';
const books: Book[] = await (await pool).query('SELECT * FROM book WHERE pages => ?', [minPages]);
So, i don't want the second await when i use the pool (if it's possible), and the dbOptions() don't works because the startConnection() function starts before the dotenv.config() in index.ts then the procces.env.something returns undefined each time, so how can i fixed that?.
Thanks for help! 😁

Answer 1

So, I cannot view all your code to help with dotenv issue, but you can pass await pool as a paramter for a callback function that starts your app. Anyway, I would implement your code by using mysql2:
database.ts:
import { createPool, Pool, PoolOptions } from "mysql2";
import keys from "./keys";
function startConnection(): Pool {
const options: PoolOptions = dbOptions({ isDev: true });
const pool: Pool = createPool(options);
return pool;
}
function dbOptions({ isDev }: {
isDev: boolean;
}): PoolOptions {
let dbConfig: PoolOptions = {
database: process.env.DB ?? (isDev &&= keys.DB.DB),
host: process.env.DB_HOST ?? (isDev &&= keys.DB.DB_HOST),
user: process.env.DB_USER ?? (isDev &&= keys.DB.DB_USER),
password: process.env.DB_U_PASS ?? (isDev &&= keys.DB.DB_U_PASS),
};
return dbConfig;
}
export const connectionPool = startConnection();
query.ts
import { connectionPool } from "database";
const books: Book[] = await connectionPool.query("SELECT * FROM book WHERE pages => ?", [minPages]);