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Multiple HTTP async request

I try to fetch data from different HTTP sources but I wasn't able to handle the asynchronous mode even with async...
var express = require('express');
var app = express();
var https = require("https");
var timer = require("./my_modules/timer/timer.js");
var http = require('http');
var bodyParser = require('body-parser');
var async = require('async');
var request = require('request');
//These are my source from API.
//Output is a Json file
var sources = {
cnn: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc',
bbc: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc',
guardian: 'https://newsapi.org/v1/articles?source=cnn&sortBy?&apiKey=c6b3fe2e86d54cae8dcb10dc77d5c5fc',
othersource: "otherurls..."
};
//I want to push the JSON object in this array
var resultArray = [];
//I setup a https GET request
var getJson = function(url) {
https.get(url, (res) => {
var body = '';
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
result = JSON.parse(body);
//push isn't working...
resultArray.push(result);
});
}).on('error', function(e) {
console.log('Got an error', e);
});
}
app.set('port', (process.env.PORT || 5000));
app.listen(
app.get('port'), () => {
console.log('We are live on port: ', app.get('port'));
getJson(sources.cnn);
});
app.use(bodyParser.urlencoded({
extended: true
}));
app.use(bodyParser.json());
app.use(function(req, res, next) {
res.setHeader('Content-Type', 'text/plain');
res.status(404).send('Page not found !');
res.status(503).send('Page not found, error 503');
});
console.log("resultArray:" + resultArray);
//resultArray = empty...
What should I do to push the result into my Array?
I couldn't find a way to set up a working callback function to push results into the Array.

Since you're already using the request package, have you tried something as simple as:
request({
url: sources.cnn,
json: true
}, function(error, response, body) {
var articles = body.articles;
// or by case, depending on what you want
// resultArray = resultArray.concat(articles);
resultArray.push({
cnn: articles
});
console.log(resultArray);
});
instead of writing your own getJson function?

Thanks Roby, your request is much clearer !
I have carefully read this really clear and helpful article : https://github.com/maxogden/art-of-node#callbacks
I think I got the logic :
//main function
function getJson(url, callback){
request({
url: url,
json: true,
callback:callback //added this
}, function(error, response, body) {
var articles = body.articles;
callback(articles);
});
}
//this callback function will be passed to the main function as the 2nd parameter
//it's possible to access "resultArray" ONLY from this function
var result = function(e){
resultArray.push(e);
console.log(resultArray);
};
//url and callback are passed as parameter
getJson(sources.cnn, result);
Thanks for the help

Node.js - jQuery. Get PDF from server and display on front-end

I'm bit stuck here. My intent is to first get all files (filenames) from a static folder + subfolders and list all on front-end.
When user clicks one of the filenames (mostly pdf's), the server returns the selected items content.
I'm able to send the pdf data as binary to front-end, but how could I display the data in a new tab with js/jQuery?
so far..
Server.js -
// Importing and initializing npm/node plugins
var app = require('express')();
var server = require('http').createServer(app);
var logger = require('morgan');
var bodyParser = require('body-parser');
var pdf = require('express-pdf');
var cors = require('cors');
var fs = require('fs');
// Import config settings
var config = require('./config.json');
app.use(logger('dev'));
// Allow application/x-www-form-urlencoded and application/json
app.use(bodyParser.urlencoded({
extended: false
}));
app.use(bodyParser.json({
limit: '50mb'
}));
app.use(cors());
app.use(pdf);
app.get('/getfiles', function (req, res) {
var dir = config.sourceDir;
var foundFiles = [];
fs.readdir(dir, function (err, files) {
if (err) {
console.log('Error reading ' + dir);
process.exit(1);
}
console.log('Listing files in Directory ' + dir);
files.forEach(function (f) {
foundFiles.push(f);
});
res.json(foundFiles);
});
});
app.post('/showfiles', function (req, res) {
var file = req.body.filename;
var dir = config.sourceDir;
fs.readFile(dir + file, function (err, data) {
res.contentType('application/pdf');
res.send(data);
});
});
// Open server in port
server.listen(config.port, function () {
console.log('Server listening on port: ' + config.port);
});
module.exports = app;
On front-end -
$(function () {
getFiles();
});
function getFiles() {
$.ajax({
type: "GET",
url: "http://localhost:3000/getfiles",
contentType: "application/json; charset=utf-8",
crossDomain: true,
dataType: "json",
success: function (data, status, jqXHR) {
if (data) {
$.each(data, function (index, value) {
$("#listContainer1").append("<li><a href='#' onclick='showFile(this)'>" + value + "</a></li>");
});
}
},
error: function (jqXHR, status) {
console.log("Error fetching data");
}
});
}
function showFile(file) {
$.ajax({
type: "POST",
data: JSON.stringify({
"filename": $(file).text()
}),
url: "http://localhost:3000/showfiles",
contentType: "application/json; charset=utf-8",
crossDomain: true,
dataType: "application/pdf",
success: function (data, status, jqXHR) {
if (data) {
var file = new Blob([data], {
type: 'application/pdf'
});
var fileURL = URL.createObjectURL(file);
window.open(fileURL);
}
},
error: function (jqXHR, status) {
console.log("Error showing file");
}
});
}
But this keeps falling into the "Error showing file" pit. :(
EDIT:
The first error was corrected by removing the "application/pdf" from post, but now its opening an empty pdf with correct page limit

On the server, change the file fetch code to this:
app.get('/showfiles/:filename', function (req, res) {
var options = {
root: config.sourceDir
};
var fileName = req.params.filename;
res.sendFile(fileName, options, function (err) {
if (err) {
// Handle error
} else {
// Handle success
}
});
});
So I switched the method to GET and used the built-in sendFile method in Express. Then on the front end it's much easier. You can get rid of the showFile function and just update the getFiles function:
function getFiles() {
$.ajax({
type: "GET",
url: "http://localhost:3000/getfiles",
contentType: "application/json; charset=utf-8",
crossDomain: true,
dataType: "json",
success: function (data, status, jqXHR) {
if (data) {
$.each(data, function (index, value) {
$("#listContainer1").append('<li>' + value + '</li>');
});
}
},
error: function (jqXHR, status) {
console.log("Error fetching data");
}
});
}
Code has not been tested and most likely has mistakes, but should give you a gist of another way you can tackle the problem.

ExpressJS does not seem to work with ajax calls

I'm trying to figure out Node.js to use as an api to do GET, POST, etc. I've been stuck trying to figure out why this post is not working.
My ajax call:
$.ajax({
method: "POST",
contentType: 'application/json',
dataType: 'json',
url: "localhost:8000/login",
data: JSON.stringify({user:"john", pass:"123"}),
error: function () {
alert('error');
},
success: function (data) {
alert('success');
}
});
In my express:
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.post('/login', function (req, res) {
var user = req.body.user;
var password = req.body.pass;
if(user == 'john' && password == '123') {
res.status(200);
} else {
res.status(401);
}
});
app.listen(8000, function () {
console.log('Example app listening on port 8000!');
});
Any help is greatly appreciated.

you should return some response from your express code, also response should be ended especially in case of just sending only the status code like res.status(401);
app.post('/login', function (req, res) {
var user = req.body.user;
var password = req.body.pass;
if(user == 'john' && password == '123') {
res.status(200).json({t:1});
} else {
res.status(401);
}
res.end();
});

This work for me:
$.ajax({
type: "POST",
contentType: 'application/json',
dataType: 'json',
url: "/login",
data: JSON.stringify({user:"john", pass:"123"}),
error: function (err) {
console.log(err);
alert('error');
},
success: function (data) {
alert('success');
}
});
app.post('/login', function (req, res, next) {
var user = req.body.user;
var password = req.body.pass;
if(user == 'john' && password == '123') {
res.status(200).json({s: 1});
} else {
res.status(401).json({e: 2});
}
});

var json = JSON.stringify({user:"john", pass:"123"});
$.ajax({
dataType: 'json',
type: "POST",
url: "/login",
data: json
}).done(function(data){
console.log("works fine");
});
Should work for an Ajax post function, sending the data to the node server.
The url needs to match the url of the app.post in the node server file, you don't need localhost in front of it.
ContentType is also not necessary and I made the json object outside of the Ajax call instead of setting it inside the Ajax call.
var express = require('express');
var parser = require('body-parser');
var app = express();
var port = 8000;
app.use(parser.urlencoded({extended: false}));
app.use(parser.json());
app.use(express.static('public'));
app.post('/login', function (req, res) {
var user = req.body.user;
var password = req.body.pass;
if(user == "john" && password == "123") {
res.status(200);
} else {
res.status(401);
}
});
var server = app.listen(port, function () {
var host = server.address().address
var port = server.address().port
console.log("App listening at http://%s:%s", host, port);
});
And that should work for the node server itself.
I set the server running, so you can always keep track of what port it's listening on, so you don't need to bother scrolling down to change the port, just change the port at the top of your file.
Further the /login was looking fine to me.
Also, I edited the app.use statements and added an extra one.

I think you have to parse request to JSON.
your code is:-
$.ajax({
method: "POST",
contentType: 'application/json',
dataType: 'json',
url: "localhost:8000/login",
//here you used JSON.stringify and on server side you have to parse it to use 'user' and 'pass' as a key of json
data: JSON.stringify({user:"john", pass:"123"}),
error: function () {
alert('error');
},
success: function (data) {
alert('success');
}
});
on the server side
<br>
app.post('/login', function (req, res) {
//parse data to JSON for further use
var dataObj = JSON.parse(req.body.data);
if(dataObj.user == 'john' && dataObj.password == '123') {
res.status(200);
} else {
res.status(401);
}
});

How do I make a post request with a JSON payload to an external API using node?

I am trying to make a POST request with a JSON payload to an external API using node.
Here is my code:
var express = require('express');
var bodyParser = require('body-parser');
var cors = require('cors');
var url = require("url");
var http = require("http");
var app = express();
app.use(cors());
app.use(bodyParser.urlencoded({ extended: false }));
app.post('/api', function(req, res) {
var query = url.parse(req.url, true).query;
var key = query.key;
console.log('JSON PAYLOAD:');
console.log(req.body); **//PAYLOAD COMES THROUGH AS EXPECTED**
var options = {};
options = {
host: 'localhost',
port: 1234,
method: 'POST',
headers: {'Content-Type': 'application/json'},
path: '/api?key=1234'
};
var request = http.request(options, function(response) {
response.setEncoding('utf-8');
var responseString = '';
response.on('data', function(data) {
responseString += data;
});
response.on('end', function() {
var resultObject = JSON.parse(responseString);
res.json(resultObject);
});
});
request.on('error', function(e) {
});
request.write(req.body) **//THIS METHOD SHOULD BE FORWARDING THE PAYLOAD BUT THIS IS NOT THE CASE...**
request.end();
});
The JSON payload comes through as expected from the origin. However I am unable to forward this payload to the external API. 'request.write(req.body)' appears to be the way to do this, however the external API is still receiving a null payload.
Any help would be appreciated. Thanks.

Try this Inside the app.post block
var options = {
host: 'localhost',
path: '/api?key=1234',
port: 1234,
method: 'POST',
headers: {'Content-Type': 'application/json'}
};
callback = function(response) {
var str = ''
response.on('data', function (chunk) {
str += chunk;
});
response.on('end', function () {
console.log(str);
});
}
var req = http.request(options, callback);
req.write(JSON.stringify(req.body));
req.end();

variable is not defined inside http request in node and express

In my express action get('items') I'm calling an external JSON-API and would like to render the API response in my local response.
Currently I get an error that my items variable is not defined inside of the http request. It seems this is a scope issue but I didn't find a solution.
What is the best way to accomplish this?
var http = require('http');
router.get('/items', function (req, res, next) {
var items;
var RemoteRequest = http.request({
method: 'GET',
path: 'myurl'
}, function (response) {
response.on('data', function (data) {
items = JSON.parse(data);
});
});
RemoteRequest .end();
res.render('new', {items: items} );
// or res.json({items: items});
});

It looks like you are not waiting for the return from your http request, you need to move the res.render('new', {items: items} ); into the callback:
var http = require('http');
router.get('/items', function (req, res, next) {
var items;
var RemoteRequest = http.request({
method: 'GET',
path: 'myurl'
}, function (response) {
response.on('data', function (data) {
items = JSON.parse(data);
res.render('new', {items: items} );
// or res.json({items: items});
});
});
RemoteRequest .end();
});