Express – Cannot access 'Database' before initialization

August 11, 2022

const express = require('express');
const upload = require("express-fileupload");
const editJsonFile = require("edit-json-file");
const fs = require('fs');
const app = express();
app.use(upload())
app.use(express.urlencoded({ extended: true }))
const playlist = editJsonFile(`${__dirname}/playlist.json`);

app.post("/upload", (req, res) => {
    //Save file from the html form to ./mp3
    var file = req.files.file;
    req.pipe(fs.createWriteStream("./mp3/" + file.name));
    res.send("File uploaded");
    playlist.append("playlist", file.name)
    playlist.save()
}),

app.get("/playlist", (req, res) => {
    console.log(playlist.get("playlist"))
    let playlist = playlist.get("playlist")
    let html = "";
    for (let i = 0; i < playlist.length; i++) {
        html += `<br>${playlist[i]}`;
    }
    res.send(html);
}),

Hey,
Im trying to make a music player, but somehow I get the error:

ReferenceError: Cannot access 'playlist' before initialization
    at C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\index.js:20:17
    at Layer.handle [as handle_request] (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\route.js:144:13)
    at Route.dispatch (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\route.js:114:3)
    at Layer.handle [as handle_request] (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\index.js:284:15
    at Function.process_params (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\index.js:346:12)
    at next (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\index.js:280:10)
    at urlencodedParser (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\body-parser\lib\types\urlencoded.js:91:7)
    at Layer.handle [as handle_request] (C:\Users\Jakob\Documents\Bots\API\PiMusicPlayerV2\node_modules\express\lib\router\layer.js:95:5)

I can write to the Database without any issues, but when I try to read from it I get the error above, what can I do?

>Solution :

app.get("/playlist", (req, res) => {
console.log(playlist.get("playlist"))
let playlist = playlist.get("playlist")

The second line console.log(playlist.get("playlist")) is trying to print the playlist variable but its declared in the next line, hence no access to that particular variable ergo the error. You can only access something after it has been initialized.