Updating JSON file NodeJS - json

Question

This is my code:
const Discord = require('discord.js');
const client = new Discord.Client();
const TOKEN = "***********";
const PREFIX = "!";
client.on("ready", function () {
console.log("Ready!");
});
client.on("message", function (message) {
if (message.author.equals(client.user)) return;
if (!message.content.startsWith(PREFIX)) return;
var args = message.content.substring(PREFIX.length).split(" ");
switch (args[0]) {
case "rules":
var _embed = new Discord.RichEmbed()
.setTitle("Ruleset")
.addField("Where is my order?", "Theres only one proper way to recive an order and help. Its a command .ticket")
.addField("Why AZATEJ is such a bitch?", "If my status is 'dont disturb' and hue is way more red than green it means I have a reason to do so, im not a dick, but i recive a shitload of messages on daily route with stupid quiestions.")
.addField("Dont ask stupid questions", "Stupid doesnt mean basic, we are up to help you but before you'll contact anyone read twice explanation documents and use a ticket.")
.setColor(0x00FFFF)
.setFooter("This message is coool !")
.setThumbnail(message.author.avatarURL);
message.channel.send(_embed);
break;
case "spotify":
var uID = message.author.id;
for (let i = 0; i < ftpr.buyers.length; i++) {
if (uID === ftpr.buyers[i].id) {
var _embed = new Discord.RichEmbed()
.setTitle("Spotify")
.addField("Username", "testsda#yahoo.com")
.addField("Password", "ithastobe8")
.setColor(0x00FFFF)
.setFooter("Sincerely, LajgaardMoneyService")
.setThumbnail(message.author.avatarURL);
message.author.send(_embed);
console.log(message.author.username + "(" + JSON.stringify(ftpr.buyers[i].id) + ") Just used the command !spotify");
break;
}
else {
message.channel.send(message.author + "You haven't got a valid subscription. This command is locked until a new one is obtained!");
break;
}
}
break;
}
});
client.on('guildMemberAdd', function(member) {
console.log("User " + member.id + " has joined the server!");
//var role = member.guild.roles.find("name", "Google!");
var myRole = member.guild.roles.find("name", "Google!");
member.addRole(myRole);
});
client.login(TOKEN);
This is the JSON file:
{
"buyers": [
{
"id": "1331499609509724162"
},
{
"id": "181336616164392960"
},
{
"id": "266389854122672128"
}
]
}
When the bot is running and im changing one of the ID's the check function in case "spotify": is still using the old id. I do not want to restart the program every time the json file updates as it should be running 24/7. I have tried const fs = require("fs"); method but it gave me this error: TypeError: Cannot read property 'buyers' of undefined json
Sincerely, Oscar

Answer 1

const fs = require("fs"); just loads the module. Put that at the top of your file.
To read the json file each time you need to check user IDs (inefficient, but should get things working), put this at the top of your spotify case:
case "spotify":
var yourjsonfile = fs.readFileSync("yourjsonfile.json");
var ftpr = JSON.parse(yourjsonfile);
var uID = message.author.id;
for (let i = 0; i < ftpr.buyers.length; i++) {
if (uID === ftpr.buyers[i].id) {
Again, this is very inefficient - you are reloading the file every time you need to check it, and it uses readFileSync(), which blocks until the file is read (it is better to utilize node's asynchronous features). So as the JSON file grows larger, this will run slower. But at that point you probably need a database or some other mechanism for persisting and querying your data.