node.js formidable make variable with uploaded file URL - node.js

Question

Hi Im using node and formidable to submit a file in a form, this file's URL I need to save in a global variable to later use it with WATSON IBM image recognition api.
I'm new with node so I'm stuck, the variable name is newpath, I'm able to print it after the form is submitted, but can't access the variable later.
I must be doing something wrong, I really appreciate if you can point me out my mistake.
const http = require('http');
var formidable = require('formidable');
const hostname = '127.0.0.1';
const port = 3500;
var fs = require('fs');
/// WATSON
var VisualRecognitionV3 = require('watson-developer-cloud/visual-recognition/v3');
var visualRecognition = new VisualRecognitionV3({
version: '2018-03-19',
iam_apikey: 'xxxxxxx'
});
// SERVER AND FORM
const server = http.createServer((req, res) => {
if (req.url == '/fileupload') {
var form = new formidable.IncomingForm();
form.parse(req, function (err, fields, files) {
var oldpath = files.filetoupload.path;
var newpath = '/users/myuser/coding/visualr/' + files.filetoupload.name;
fs.rename(oldpath, newpath, function (err) {
if (err) throw err;
res.write('File uploaded and moved!');
// this is the path, variable newpath, but can't be accessed
// outside this function, tried to make it global but didn't work either
res.write('newpath');
res.end();
});
});
} else {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
res.write('<input type="file" name="filetoupload"><br>');
res.write('<input type="submit">');
res.write('</form>');
return res.end();
}
});
var images_file = fs.createReadStream(newpath);
// I want to put the variable newpath in this function: but it doesn't work...
var params = {
images_file: images_file,
};
visualRecognition.classify(params, function(err, response) {
if (err)
console.log(err);
else
console.log(JSON.stringify(response, null, 2))
});
// ENDS
server.listen(port, hostname, () => {
console.log(`Server running at http://${hostname}:${port}/`);
});

Answer 1

The variable is defined within the context of the if (req.url == '/fileupload') {...} block, so it won't be available outside of that block.
To use the variable everywhere in the code, define it outside of the createServer block:
var newpath; // this variable will have global context for this file
const server = http.createServer((req, res) => {
if (req.url == '/fileupload') {
var form = new formidable.IncomingForm();
form.parse(req, function (err, fields, files) {
var oldpath = files.filetoupload.path;
// set the variable to its intended value here
newpath = '/users/myuser/coding/visualr/' + files.filetoupload.name;
fs.rename(oldpath, newpath, function (err) {
if (err) throw err;
res.write('File uploaded and moved!');
res.write('newpath');
res.end();
});
});
} else {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
res.write('<input type="file" name="filetoupload"><br>');
res.write('<input type="submit">');
res.write('</form>');
return res.end();
}
});
console.log(newpath); // the variable should be available here, because of its context