Call python script from express

Question

I am trying to run a python script with child_process, I am testing with a simple script that prints hello but the output I am getting back is undefinedhello

script.py

#!/usr/bin/python3

print ('hello')

app.js

router.get('/hello', (req, res) => {
    const spawn = require('child_process').spawn;
    const py = spawn('/usr/bin/python3', ['./python/script.py']);
    
    let output;
    py.stdout.on("data", (data) => {
          output += data;
    });
    py.stdout.on("close", () => {
        console.log(output);
        res.sendStatus(200);
    });
});

I have tried several suggestions but none have worked

Ashutosh Patole · Accepted Answer · 2021-03-28 13:34:17Z

1

const spawn = require('child_process').spawn;     // this should be out of the router

router.get('/hello', (req, res) => {
    
    const py = spawn('/usr/bin/python3', ['./python/script.py']);
    
    let output;
    py.stdout.on("data", (data) => {
          output += data.toString();
    });
    py.on("close", () => {                     // this differs 
        console.log(output);
        res.sendStatus(200);
    });
});

Reference child_process

answered Mar 28, 2021 at 13:34

Ashutosh Patole

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1 Comment

Gary Over a year ago

Just to add I need to do let output = ""; to remove undefined.

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