how do we use variables outside of process.stdout.on(....)? - node.js

Question

i'm receiving a variable from python script in node.js.
I read this variable with :
subprocess.stdout.on('data', (data) => {
dataString += data.toString();
})
but i can't use "dataString" outside of "subprocess.stdout.on", it's just empty.
I need the data received from python to use it elsewhere.
any solution for this one please?

Answer 1

node.js file :
const path = require('path')
const {spawn} = require('child_process')
const fs = require('fs')
var img = "./img/facture1.jpg"
const data64 = fs.readFileSync(img, 'base64')
const fetch = require("node-fetch")
var dataString = '';
var r = spawn('python', [
"-u",
path.join(__dirname, 'my_script.py'),
img,
]);
r.stdin.write(data64);
r.stdin.end();
function runScript(){
return r
}
const subprocess = runScript()
subprocess.stdout.on('data', (data) => {
dataString += data.toString();
})
subprocess.stdout.on('end', () =>{
dataStr = dataString;
console.log("\n i'm from python",dataString);
});
python file :
#!/usr/bin/python
import io
import os
import sys, json
import base64
from typing import IO
from PIL import Image
import cv2
import numpy as np
import PIL.Image
import pytesseract
from pytesseract import image_to_string
def read_in():
lines = sys.stdin.readlines()
return lines
def stringToRGB(base64_string):
imgdata = base64.b64decode(str(base64_string))
image = Image.open(io.BytesIO(imgdata))
return cv2.cvtColor(np.array(image), cv2.COLOR_BGR2RGB)
def search_string_in_file(file_name, string_to_search1,string_to_search2):
line_number = 0
list_of_results = []
with open(file_name, 'r') as read_obj:
for line in read_obj:
line_number += 1
if string_to_search1 in line:
list_of_results.append(line.rstrip())
if string_to_search2 in line:
list_of_results.append(line.rstrip())
return list_of_results
def main():
lines = read_in()
window_name = 'Image'
image = stringToRGB(lines)
imS = cv2.resize(image, (960, 700))
pytesseract.pytesseract.tesseract_cmd = r"./Tesseract-OCR/tesseract.exe"
image_to_text = pytesseract.image_to_string(image, lang='eng')
name = sys.argv[1]
name = name[2:-4]
f = open('%s.txt' % name, "w")
f.write(image_to_text)
f.close()
matched_lines = search_string_in_file('%s.txt' % name, 'Total', 'A PAYER')
for elem in matched_lines:
elem = elem[14:18]
print("\n",elem)
if __name__ == "__main__":
main()