Nodejs and postgresql and promises and ES6 - node.js

Question

I'm pretty new to nodejs, I use just ES6 and I massively use generators.
I'm trying to promisfy the "connect" and "query" function of pg module.
Why the following snippet doesn't release the main execution context and keeps the script running from shell? It works correctly but it hangs after printing the result.
Disclaimer: I'm not interested in Bluebird.promisfy function nor pg-promise, knex and bookshelf modules. None of these fits my needs.
'use strict';
let co = require('co');
let pg = require('pg').native;
function connect(hostname, username, password, database) {
let connectionString = `postgres://${username}:${password}#${hostname}/${database}`;
return new Promise((resolve, reject) => {
pg.connect(connectionString, function(error, result, done) {
if(error)
return reject(error);
else
return resolve({ connection: result, release: done });
});
});
}
function query(connection, text, values) {
return new Promise((resolve, reject) => {
connection.query(text, values, (error, result) => {
if(error)
return reject(error);
else
return resolve(result);
});
});
}
co(function*(){
try {
let hostname = 'localhost';
let username = 'damiano';
let password = 'damiano';
let database = 'graph';
let client = yield connect('localhost', 'user', 'pass', 'graph');
let result = yield query(client.connection, `select * from vertices v1, vertices v2 limit 1`);
client.release();
return result;
}
catch(error) {
console.log(error);
}
}).then((result) => {
console.log(result.rows);
return;
});
Edit:
Ok the connection was hanging. The done method doesn't seem to do nothing, there is a hidden method .end on the connection itself.

Answer 1

Even since it is not answer for exact question, I'm still gonna recommend something different. I successfully use for this sequilizejs with koa and co. Sequilize's methods return promises, so I yielding them directly let rows = yield table.findAll({ where: { age: 18 }, raw: true }); And I dont have to worry about connections.