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Cannot set headers after they are sent to the client, how do I stop Express from setting headers that have already been set?

I'm using Express, Node, and EJS to fetch data from Spotify Web API. Without EJS, I'm able to send a request from browser and fetch data no problem. With EJS, code crashes with code: 'ERR_HTTP_HEADERS_SENT' once I send a request in the browser. I'm lost on how to stop express from sending headers that have already been set.
const express = require("express");
const request = require("request");
const app = express();
const secret = require("./secret");
const redirect_uri = "http://localhost:8888/callback";
const client_id = secret.client_id;
const client_secret = secret.client_secret;
const querystring = require("querystring");
let state = "abc123";
let scope =
"user-read-private user-read-email user-read-recently-played user-top-read";
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.set("view engine", "ejs");
// Request User Authorization
app.get("/login", function (req, res) {
return res.redirect(
"https://accounts.spotify.com/authorize?" +
querystring.stringify({
response_type: "code",
client_id: client_id,
scope: scope,
redirect_uri: redirect_uri,
state: state,
})
);
});
// Request Access Token
app.get("/callback", function (req, res) {
let code = req.query.code || null;
state = req.query.state || null;
if (state === null) {
return res.redirect(
"/#" +
querystring.stringify({
error: "state_mismatch",
})
);
} else {
authOptions = {
url: "https://accounts.spotify.com/api/token",
form: {
code: code,
redirect_uri: redirect_uri,
grant_type: "authorization_code",
},
headers: {
Authorization:
"Basic " +
new Buffer(client_id + ":" + client_secret).toString("base64"),
},
json: true,
};
}
// User Recently Played Tracks
request.post(authOptions, function (error, response, body) {
if (!error && response.statusCode === 200) {
let access_token = body.access_token;
let refresh_token = body.refresh_token;
let options = {
url: "https://api.spotify.com/v1/me/player/recently-played",
headers: { Authorization: "Bearer " + access_token },
json: true,
};
// use the access token to access the Spotify Web API
request.get(options, function (error, response, body) {
let items = body.items;
// Track Names
for (let i = 0; i < items.length; i++) {
let trackName = items[i].track.name;
console.log(trackName);
}
// Artist Names
for (let i = 0; i < items.length; i++) {
let artistName = items[i].track.artists[0].name;
console.log(artistName);
}
});
// we can also pass the token to the browser to make requests from there
return res.redirect(
"/#" +
querystring.stringify({
access_token: access_token,
refresh_token: refresh_token,
})
);
} else {
return res.redirect(
"/#" +
querystring.stringify({
error: "invalid_token",
})
);
}
});
return res.render("index");
});
// Refresh Token
app.get("/refresh_token", function (req, res) {
let refresh_token = req.query.refresh_token;
let authOptions = {
url: "https://accounts.spotify.com/api/token",
headers: {
Authorization:
"Basic " +
new Buffer(client_id + ":" + client_secret).toString("base64"),
},
form: {
grant_type: "refresh_token",
refresh_token: refresh_token,
},
json: true,
};
request.post(authOptions, function (error, response, body) {
if (!error && response.statusCode === 200) {
let access_token = body.access_token;
return res.send({
access_token: access_token,
});
}
});
});
app.listen(8888, () => console.log("Server started on port 8888"));

Can't access /playlists using express and app.get

I'm trying to access the app.get('/playlists') but it keeps coming up a 404 status code error and the browser is displaying cannot GET /playlists
I'm unsure what I'm doing tthat is isn't accessible here's the code:
var express = require('express'); // Express web server framework
var stateKey = 'spotify_auth_state';
var app = express();
app.use(express.static(__dirname + '/public'))
.use(cors())
.use(cookieParser());
app.get('/callback', function(req, res) {
// your application requests refresh and access tokens
// after checking the state parameter
var code = req.query.code || null;
var state = req.query.state || null;
var storedState = req.cookies ? req.cookies[stateKey] : null;
if (state === null || state !== storedState) {
res.redirect('/#' +
querystring.stringify({
error: 'state_mismatch'
}));
} else {
res.clearCookie(stateKey);
var authOptions = {
url: 'https://accounts.spotify.com/api/token',
form: {
code: code,
redirect_uri: redirect_uri,
grant_type: 'authorization_code'
},
headers: {
'Authorization': 'Basic ' + (new Buffer(client_id + ':' +
client_secret).toString('base64'))
},
json: true
};
request.post(authOptions, function(error, response, body) {
if (!error && response.statusCode === 200) {
var access_token = body.access_token,
refresh_token = body.refresh_token;
var options = {
url: 'https://api.spotify.com/v1/me',
headers: { 'Authorization': 'Bearer ' + access_token },
json: true
};
// use the access token to access the Spotify Web API
request.get(options, function(error, response, body) {
console.log(body);
});
// we can also pass the token to the browser to make requests from there
res.redirect('/#' +
querystring.stringify({
access_token: access_token,
refresh_token: refresh_token
}));
} else {
res.redirect('/#' +
querystring.stringify({
error: 'invalid_token'
}));
}
});
}
});
app.get('/refresh_token', function(req, res) {
// requesting access token from refresh token
var refresh_token = req.query.refresh_token;
var authOptions = {
url: 'https://accounts.spotify.com/api/token',
headers: { 'Authorization': 'Basic ' + (new Buffer(client_id + ':' + client_secret).toString('base64')) },
form: {
grant_type: 'refresh_token',
refresh_token: refresh_token
},
json: true
};
request.post(authOptions, function(error, response, body) {
if (!error && response.statusCode === 200) {
var access_token = body.access_token;
res.send({
'access_token': access_token
});
}
});
app.get('/playlists', (req, res) => {
console.log(request.url);
response.send('Hello, /');
});
});
console.log('Listening on 8888');
app.listen(8888);
I can't figure out why the route won't work

Your /playlists endpoint is declared inside of the /refresh_token endpoint. Moving it outside of that should work.

Refresh access token express js

I have an express server that gets a list of podcasts, from an endpoint.
This apart works fine, but there is a token that I use in requests to authorize entry to the endpoints.
the response when gaining an access token looks like:
{ access_token: '8c9d31761cbd32da25f1f1b988b527cde01c9d8a',
expires_in: 604800,
token_type: 'Bearer',
scope: 'podcast_read episode_read podcast_update episode_publish' }
I have a refresh token that I use when refreshing the token and works well.
The way I'm doing it at the moment is, I have a text file that holds the token, the app reads from this when making a request, I have set up a function, that is called every time the podcasts route is called router.get('/podcasts', checkIfTokenValid, (req, res, next) => { to check if the token is valid or expired if so, refresh the token and write the new token to the file.
The only thing about this is; the write to file function is executed after the podcasts route connects to the endpoint, so the old access token is used.
Logging to the console, the functions are executed before the podcasts route gets all the podcasts, except for the writeAccessTokenToFile() function.
Just wondering, is there a better way to do this?
var express = require('express');
var router = express.Router();
var app = express();
var path = require('path');
var fs = require('fs');
const request = require('request');
var refreshToken = '425153ed4ddb4aee5sjsjsfaeffc46ab9944aece0400f';
var clientId = 'myId';
var client_secret = 'secret';
var isAccessTokenValid;
var access_token_file = path.join(__dirname, 'access_token.txt');
function refreshAccessToken() {
console.log('refreshAccessToken')
var body = { 'grant_type': 'refresh_token', 'refresh_token': refreshToken }
var options = {
url: `https://api.podbean.com/v1/oauth/token`,
headers: { 'Authorization': 'Basic ' + new Buffer(clientId + ":" + client_secret).toString('base64') },
json: body
}
request.post(options, (err, response, body) => {
// console.log(body.expires_in*1000)
if (err) {
return response.status(500).json({
title: 'An error has occured',
error: err
})
}
console.log(body)
writeAccessTokenToFile(body.access_token);
})
}
function getAccessToken() {
return fs.readFileSync(access_token_file, 'utf8');
}
function writeAccessTokenToFile(token) {
console.log('writeAccessTokenToFile = '+ token)
var data = getAccessToken();
var result = data.replace(data, token);
fs.writeFileSync(access_token_file, result, 'utf8');
}
function checkIfTokenValid (req, res, next) {
console.log('checkIfTokenValid')
var options = {
url: `https://api.podbean.com/v1/oauth/debugToken?access_token=${getAccessToken()}`,
headers: { 'Authorization': 'Basic ' + new Buffer(clientId + ":" + client_secret).toString('base64') }
}
request(options, (err, response, body) => {
if (err) {
return res.status(500).json({
title: 'An error has occured',
error: err
})
}
// console.log(JSON.parse(body))
isAccessTokenValid = JSON.parse(body).is_valid;
if (isAccessTokenValid) {
refreshAccessToken();
}
next();
})
};
router.get('/podcasts', checkIfTokenValid, (req, res, next) => {
var options = {
url: `https://api.podbean.com/v1/podcasts?access_token=${getAccessToken()}`
}
request(options, (err, response, body) => {
if (err) {
return res.status(500).json({
title: 'An error has occured',
error: err
})
}
res.json(JSON.parse(body));
next();
})
});
module.exports = router;

NodeJS Http Post JSON Data

How do I properly send JSON data over Http Post on NodeJS? I have checked that the data I'm sending is definitely JSON but every time I try sending over http post, it would receive an error. I cant exactly see the error as it's returning from terminal and even if I output, it's too messy, not properly formatted
var options = {
hostname: 'www.postcatcher.in',
port: 80,
path: '/catchers/5531b7faacde130300002495',
method: 'POST',
headers: {
'Content-Type': 'application/json',
}
};
var req = http.request(options, function(res) {
console.log('Status: ' + res.statusCode);
console.log('Headers: ' + JSON.stringify(res.headers));
res.setEncoding('utf8');
res.on('data', function (body) {
console.log('Body: ' + body);
fs.writeFile("/var/www/node/test.txt", body, function(err) {
if(err) {
return console.log(err);
}
console.log("The file was saved!");
});
});
});
req.on('error', function(e) {
console.log('problem with request: ' + e.message);
});
// write data to request body
req.write('{"string": result}'); ///RESULT HERE IS A JSON
req.end();
Also tried this
// request.post(
// '',
// { form: { key: result } },
// function (error, response, body) {
// if (!error && response.statusCode == 200) {
// console.log(body);
// }
// }
// );
// console.log(result);

result is not being interpolated.
this seems to work correctly..
http = require('http');
fs = require('fs');
var options = {
hostname: 'www.postcatcher.in',
port: 80,
path: '/catchers/5531b7faacde130300002495',
method: 'POST',
headers: {
'Content-Type': 'application/json',
}
};
var req = http.request(options, function(res) {
console.log('Status: ' + res.statusCode);
console.log('Headers: ' + JSON.stringify(res.headers));
res.setEncoding('utf8');
res.on('data', function (body) {
console.log('Body: ' + body);
fs.writeFile("test.txt", body, function(err) {
if(err) {
return console.log(err);
}
console.log("The file was saved!");
});
});
});
req.on('error', function(e) {
console.log('problem with request: ' + e.message);
});
// write data to request body
// req.write('{"string": result}'); ///RESULT HERE IS A JSON
result = '{ "hello": "json" }';
req.write('{"string": '+result+'}');
req.end();
result:
$ node 29712051.js
Status: 201
Headers: {"server":"Cowboy","date":"Sat, 18 Apr 2015 04:23:52 GMT","connection":"keep-alive","x-powered-by":"Express","content-type":"text/plain","content-length":"7","set-cookie":["connect.sid=0eGSTYI2RWf5ZTkpDZ0IumOD.OrcIJ53vFcOiQSdEbWz0ETQ9n50JBnXyZRjrSyFIdwE; path=/; expires=Sat, 18 Apr 2015 08:23:53 GMT; httpOnly"],"x-response-time":"6ms","via":"1.1 vegur"}
Body: Created
The file was saved!
$ cat test.txt
Created

actually, u can use JSON.stringify(result) to instead '{"string": '+result+'}':
http = require('http');
fs = require('fs');
var options = {
hostname: 'www.postcatcher.in',
port: 80,
path: '/catchers/5531b7faacde130300002495',
method: 'POST',
headers: {
'Content-Type': 'application/json',
}
};
var req = http.request(options, function(res) {
console.log('Status: ' + res.statusCode);
console.log('Headers: ' + JSON.stringify(res.headers));
res.setEncoding('utf8');
res.on('data', function (body) {
console.log('Body: ' + body);
fs.writeFile("test.txt", body, function(err) {
if(err) {
return console.log(err);
}
console.log("The file was saved!");
});
});
});
req.on('error', function(e) {
console.log('problem with request: ' + e.message);
});
// write data to request body
// req.write('{"string": result}'); ///RESULT HERE IS A JSON
//
result = JSON.stringify({ hello: "json" });
req.write('{"string": '+result+'}');
//
req.end();

Http get multiple json files from different API endpoints using node express

I'm looking into the most efficient way to get multiple JSON files from different API endpoints using node.
Basically i'd like to store each JSON object in a variable, and send them all to Jade template files for parsing.
I've got it setup working for getting one single JSON file (jsonFile1) by doing the following:
httpOptions = {
host: 'api.test123.com',
path : '/content/food/?api_key=1231241412',
headers: {
"Accept": "application/json",
'Content-Type': 'application/json'
},
method: "GET",
port: 80
}
var jsonFile1;
http.get(httpOptions, function(res) {
var body = '';
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
jsonFile1= JSON.parse(body)
console.log("Got response: " + jsonFile1);
});
}).on('error', function(e) {
console.log("Got error: " + e.message);
});
app.set('views', __dirname);
app.get('/', function(req, res) {
res.render('home', {
data: jsonFile1
});
});
But i don't really want to have to repeat all of this to get multiple json endpoints and send them to home jade template.
Any ideas to do this efficiently?

Based on your code, this is a quick example using the excellent async library.
var async = require('async'),
// Array of apis
httpOptions = [
{
host: 'api.test123.com',
path : '/content/food/?api_key=1231241412',
headers: {
"Accept": "application/json",
'Content-Type': 'application/json'
},
method: "GET",
port: 80
},
host: 'api.test234.com',
path : '/content/food/?api_key=1231241412',
headers: {
"Accept": "application/json",
'Content-Type': 'application/json'
},
method: "GET",
port: 80
}
];
// Put the logic for fetching data in its own function
function getFile(options, done) {
http.get(options, function(res) {
var body = '';
res.on('data', function(chunk) {
body += chunk;
});
res.on('end', function() {
done(null, JSON.parse(body));
console.log("Got response: " + jsonFile1);
});
}).on('error', function(e) {
done(e);
console.log("Got error: " + e.message);
});
}
app.get('/', function(req, res) {
// Map the options through the getFile function, resulting in an array of each response
async.map(httpOptions, getFile, function (err, jsonFiles) {
// You should probably check for any errors here
res.render('home', {
data: jsonFiles
});
});
});