How to connect PostgreSQL to NodeJS right way?

Question

I can't understand how to connect PostgreSQL pool in NodeJS and do it correctly. I am using Express with Router, all handlers are placed in different files. Everyone advises to make a separate file with a DB connection and then "require" it in each source code file. Is it possible to connect this pool through app.use or something else? All my handlers always use DB connection, for each user request.

Answer 1

I'm pretty sure the example below is what others are telling you to do, this utilizes the postgres' pooling.

If there's another method that would be as simple as a require and technically 2 loc per file, I'd love to hear it.

Example of a required querydb file:

"use strict";

const pg = require('pg');

const config = {
  connectionString: 'postgres://username:password@server/database'
};

const pool = new pg.Pool(config);

const DB = {
    query: function(query, callback) {
        pool.connect((err, client, done) => {
            if(err) return callback(err)
            client.query(query, (err, results) => {
                done()
                if(err) { console.error("ERROR: ", err) }
                if(err) { return callback(err) }
                callback(null, results.rows)
            })
        });
    }
}

Then anywhere when you want to query the database you just use the few lines below instead of copy/pasting the entire connection pooling method.

Example usage

const queryDB = require("../queryDB.js");

... 
let query = "SELECT * FROM table;"
queryDB.query(query, (err, results) => {
    // Handle err/results
})