Node.js async - build object from loop, then do something with object - node.js

Question

I'm trying to run a function and once that function is complete, then run another function. The first function reads a CSV file, makes a GET request, and builds an object. The second function uses that newly created object to create a new CSV file.
The problem I'm having is that the new CSV file is being created prior to the GET requests finishing.
I'm using async.parallel to set the flow, but not able to get the logic right.
I'd love to know what I'm doing wrong and better understand how node thinks about these tasks.
// Require
var request = require('request');
var fs = require('fs');
var json2csv = require('json2csv');
var csv = require('csv');
var async = require('async');
// Params
var emailHunter_apiKey = '0000';
var emails = [];
var fields = ['email'];
var i = 0;
// Start
async.parallel([
function(callback){
setTimeout(function(){
var file = fs.readFileSync('file.csv');
csv.parse(file, {delimiter: ','}, function (err, data) {
for (var key in data) {
if (i < 5) {
if (data.hasOwnProperty(key)) {
var h = data[key];
if (h[5] != '') {
var url = h[5];
url = url.replace('//', '');
url = url.replace('www.', '');
request('https://api.emailhunter.co/v1/search?domain=' + url + '&api_key=' + emailHunter_apiKey + '', function (error, response, body) {
if (!error && response.statusCode == 200) {
var json = JSON.parse(body);
for (var subObj in json) {
if (json.hasOwnProperty(subObj) && subObj == 'emails') {
var emailObj = json[subObj];
for (var key in emailObj) {
var email = {
'email': emailObj[key]['value']
};
emails.push(email);
}
}
}
}
});
}
}
}
i++;
}
});
callback(null, emails);
}, 200);
console.log(emails);
}
],
function(err, results){
json2csv({data: results, fields: fields}, function (err, csv) {
if (err) console.log(err);
fs.writeFile('export.csv', csv, function (err) {
if (err) throw err;
console.log('file saved');
});
});
console.log(results);
});

Answer 1

As laggingreflex mentioned, you're using async incorrectly.
First you should build a an array of functions that you want to execute in parallel. And then use async to execute them.
Furthermore, your callback was getting executed immediately because csv.parse() is an async function. Therefore node fires it immediately and then executes callback(). You need to move the callback inside of parse().
Try this...
// Params
var emailHunter_apiKey = '0000';
var emails = [];
var fields = ['email'];
var i = 0;
var functionsToRunAsync = [];
var file = fs.readFileSync('file.csv');
csv.parse(file, {delimiter: ','}, function (err, data) {
for (var key in data) {
if (i < 5) {
if (data.hasOwnProperty(key)) {
var h = data[key];
if (h[5] != '') {
var url = h[5];
url = url.replace('//', '');
url = url.replace('www.', '');
// add a new function to an array, to be executed later
functionsToRunAsync.push(function(callback) {
request('https://api.emailhunter.co/v1/search?domain=' + url + '&api_key=' + emailHunter_apiKey + '', function (error, response, body) {
if (!error && response.statusCode == 200) {
var json = JSON.parse(body);
for (var subObj in json) {
if (json.hasOwnProperty(subObj) && subObj == 'emails') {
var emailObj = json[subObj];
for (var key in emailObj) {
var email = {
'email': emailObj[key]['value']
};
emails.push(email);
// callback to tell async this function is complete
callback()
}
}
}
} else {
// callback to tell async this function is complete
callback
}
});
});
}
}
}
i++;
}
// now that we have all of the functions in an array, we run them in parallel
async.parallel(
functionsToRunAsync,
function(err, results) { // all async functions complete
json2csv({data: results, fields: fields}, function (err, csv) {
if (err) console.log(err);
fs.writeFile('export.csv', csv, function (err) {
if (err) throw err;
console.log('file saved');
});
});
console.log(results);
});
});