Run python script from Node.js (child_process) with named arguments

Question

I have a python script which can be run with this argument on the command line:

python2 arg1 --infile abc.csv --encrypt true --keyfile xyz.bin 1234 WOW path

However, if I try to do the same thing from Node.js child process, I get an error:

const spawn = require("child_process").spawn;

const process = spawn("python2", [
  path.join(rootDir, "public", "python", "script.py"),
  "arg1",
  "--infile abc.csv",
  "--encrypt true",
  "--keyfile xyz.bin",
  "1234",
  "WOW",
  "path",
]);

It is not running and giving an error. But, If I run without the NAMED ARGUMENTS (--encrypt true) etc, it runs successfully:

const process = spawn("python2", [
  path.join(rootDir, "public", "python", "script.py"),
  "arg1",
  "1234",
  "WOW",
  "path",
]);

I think my way of passing the NAMED args might be incorrect. Please help!

Answer 1

You need to split each part of the argument:

const process = spawn("python2", [
  path.join(rootDir, "public", "python", "script.py"),
  "arg1",
  "--infile",
      "abc.csv", // indentation for clarity, it's not necessary
  "--encrypt",
      "true",
  "--keyfile",
      "xyz.bin",
  "1234",
  "WOW",
  "path",
]);

Your original script is similar to running this on the command prompt:

python script.py arg1 "--infile abc.csv" "--encrypt true" "--keyfile xyz.bin" 1234 WOW path

Basically you are passing the argument named --infile abc.csv with the value --encrypt true. Which is not what you intend to run. What you want is:

python script.py arg1 --infile abc.csv --encrypt true --keyfile xyz.bin 1234 WOW path