3

Using child_process.spawn in node.js to execute a python script via an electron app (node.js). If I run the python script on terminal (macOS) there are no problems, but, using node.js and:

const spawn = require('child_process').spawn
let ls = spawn('python', ['runserver.py','--help'], {
  cwd: __dirname,
  detached: true
})

I get errors from python of failed module imports, such as:

Traceback (most recent call last):
  File "runserver.py", line 17, in <module>
    from queue import Queue
ImportError: No module named queue

I've already tried setting different environments with no luck.

Edit:

Here are the logs of sys.path:

  • from code execution via child_process

    [
  '/Users/xAlien95/Desktop/test.app/Contents/Resources/app',
  '/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
  '/Library/Python/2.7/site-packages',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python',
  '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC'
]

  • from code execution via terminal

    [
  '/Users/xAlien95/Desktop/test.app/Contents/Resources/app',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
  '/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
  '/usr/local/lib/python2.7/site-packages',
  '/usr/local/Cellar/protobuf/3.1.0/libexec/lib/python2.7/site-packages'
]

So, in terminal it's using the homebrew downloaded Python framework. How could I ensure the same will happen in the node.js app?

Stephen Rauch
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xAlien95
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  • Have the python script print/log sys.path. Make sure the python install is present. http://stackoverflow.com/questions/897792/where-is-pythons-sys-path-initialized-from – Stephen Rauch Jan 04 '17 at 15:10
  • @StephenRauch, thanks for your suggestion, I edited the question. Is there a way to easily set that environment in nodejs? – xAlien95 Jan 04 '17 at 15:52

1 Answers1

3

One way to have python find different libraries is to use the environment variable PYTHONPATH. You can set this in node.js using process.env.PYTHONPATH

(DOCS) (SOURCE)

For the specific case of wanting to run the homebrew installed python, the python executable should be available at:

let ls = spawn(process.env.HOMEBREW_PREFIX + '/bin/python', ['runserver.py','--help'], {
    ...

If HOMEBREW_PREFIX is not available inprocess.env, and the path to the desired python is known, it can be hard-coded into the spawn:

let ls = spawn(/*<Where my python lives>*/ + '/bin/python', ['runserver.py','--help'], {
    ...
Community
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Stephen Rauch
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  • Unfortunately there's no `PYTHONPATH` or `HOMEBREW_PREFIX` in my `process.env` Object. But it works if I put `'/usr/local/Cellar/python/2.7.13/bin/python'`. Just edit your answer with "if process.env.HOMEBREW_PREFIX isn't available, just put the full string path before" and I'll mark it as answered. Thank you! – xAlien95 Jan 04 '17 at 17:10
  • Hey, so in my case too, there are no PYTHONPATH or HOMEBREW_PREFIX and even with the absolute path, I got the same problem. I am not sure I have the right path although. Sometimes I got : spawn ENOTDIR Error ! @xAlien95 please help – AsmaG Nov 09 '17 at 20:39