Nodejs - running external process

Question

Need to build a back-end service using node-js which does the following.

1. Accepts file-upload from client (browser)
2. Save the file on disk and update DB ( mongodb ) with new filename and status as saved
3. Starts an long running process to parse the file ( written in python) and get feedback ( progress, error, success) , update DB with status feedback

How do we call # 3 from node.js - it could be system call like python parse_file.py filename

app.post('/upload',function(req,res, next){

       // what should go here to call the process

        res.writeHead(201, {'Content-type': 'text/plain'});
        res.end("File uploaded.");
    }
});

Answer 1

You can use require('child_process').spawn() or require('child_process').exec() to spawn a child process. The docs for those can be found at https://nodejs.org/dist/latest-v6.x/docs/api/child_process.html#child_process_child_process_spawn_command_args_options