NodeJS table children are undefined - node.js

Question

I've been working on a discord/roblox bot. I've gotten almost finished, but ran into a problem. I'm a noob at node, so please dont harp too much if the code is bad. What this does is I click a button in a roblox game, it sends a POST request to a heroku app, and then with the info provided it sends a message to a channel in my discord server.
Relevant bits of code:
const Discord = require('discord.js');
const request = require('request');
var express = require('express');
app = express();
bodyParser = require('body-parser');
path = require('path');
var bodyParser = require('body-parser');
var PORT = process.env.PORT || 5000;
const bot = new Discord.Client();
function GetData(id){
let url = "https://economy.roblox.com/v1/assets/"+id+"/resale-data";
let url2 = "https://thumbnails.roblox.com/v1/assets?assetIds="+id+"&size=150x150&format=Png";
let url3 = "http://api.roblox.com/marketplace/productinfo?assetId="+id
let options = {json: true};
var response = {};
request(url, options, (error, res, body) => {
if (error) {
return console.log(error)
};
if (!error && res.statusCode == 200) {
response.rap = body.recentAveragePrice
console.log(response)
};
});
request(url2, options, (error, res, body) => {
if (error) {
return console.log(error)
};
if(!error && res.statusCode == 200) {
response.thumbnail = body.data[0].imageUrl
console.log(response)
}
});
request(url3, options, (error, res, body) => {
if (error) {
return console.log(error)
};
if(!error && res.statusCode == 200) {
response.name = body.Name
console.log(response)
}
});
return response
};
app.post('/exec', function(req, res) {
res.setHeader('Content-Type', 'application/json')
res.send(JSON.stringify({
success: true
}));
console.log("working");
console.log(req.body)
var data = GetData(req.body.id)
if (req.body.state === true){
var state = "New Projected"
} else {
var state = "No longer projected"
}
const msg = new Discord.RichEmbed()
.setDescription(data.name)
.setAuthor(state)
.setColor(0x1c90d9)
.addField("RAP:", data.rap)
.setImage(data.thumbnail)
bot.channels.get("655196831835226133").send(msg);
});
However, this is the message that is sent in the discord server:
everything is undefined and there is no thumbnail
Help is greatly appreciated. Thanks a lot.

Answer 1

Some reading here: https://www.promisejs.org/
Asynchronous functions, like making a request to a server, take time to return and do so in a callback. You have to keep track of the paths of the callbacks to make sure you do not do the next step before a previous step has completed otherwise you will skip over it entirely. It is not like calling a regular function that does something in order.
When you do return response at the end of GetData, there is nothing in the object because you need to wait for the three responses to complete within their respective callbacks. You are seeing things logged to the console because they are happening after the fact in the background. If you were to put timestamps and additional logging, you would see that it is not all happening in the order of how you wrote it, but rather in order of when the requests themselves complete.
There are many different ways to write and use promises, but a very simple one here would be to nest the requests so they happen one after the other, and then finally resolve the promise at the very end when your response object has all the data. With Promises you resolve which is the same as returning, and reject when you want to raise an error.
Without going too deep into it, here is an example of what you can do. This is untested as I am not running your application or trying to rewrite it, that is not was StackOverflow is for, but hopefully it can send you in the right direction. Note that I call reject on the errors to tell the promise to stop running.
function GetData(id){
// declare the Promise
return new Promise((resolve, reject) => {
let url = "https://economy.roblox.com/v1/assets/"+id+"/resale-data";
let url2 = "https://thumbnails.roblox.com/v1/assets?assetIds="+id+"&size=150x150&format=Png";
let url3 = "http://api.roblox.com/marketplace/productinfo?assetId="+id
let options = {json: true};
var response = {};
// make request 1
request(url, options, (error1, res1, body1) => {
if (error1) {
console.log(error1)
// reject
reject(error1);
};
if (!error1 && res1.statusCode == 200) {
// all good, continue
response.rap = body1.recentAveragePrice
console.log(response)
// make request 2
request(url2, options, (error2, res2, body2) => {
if (error2) {
console.log(error2)
// reject
reject(error2);
};
if(!error2 && res2.statusCode == 200) {
// all good, continue
response.thumbnail = body2.data[0].imageUrl
console.log(response)
// make request 3
request(url3, options, (error3, res3, body3) => {
if (error3) {
console.log(error3)
// reject
reject(error3);
};
if(!error3 && res3.statusCode == 200) {
response.name = body3.Name
console.log(response)
// finally, resolve the final response object
resolve(response);
}
});
}
});
};
});
});
};
Now to the calling function. You still call GetData() but you use the then() function to get what was resolved, or catch() to catch any errors. I would also suggest putting your res.send() functions at the end, unless you absolutely need to return right away as your originally wrote it.
app.post('/exec', function(req, res) {
res.setHeader('Content-Type', 'application/json')
console.log("working");
console.log(req.body)
// get all the data as a Promise
GetData(req.body.id)
.then((data) => {
// now you have your data!
if (req.body.state === true){
var state = "New Projected"
} else {
var state = "No longer projected"
}
const msg = new Discord.RichEmbed()
.setDescription(data.name)
.setAuthor(state)
.setColor(0x1c90d9)
.addField("RAP:", data.rap)
.setImage(data.thumbnail)
bot.channels.get("655196831835226133").send(msg);
res.send(JSON.stringify({
success: true
}));
})
.catch((err) => {
// you can handle errors here that were rejected in the promise, if necessary
res.send(JSON.stringify({
success: false
}));
})
});