set env variable in node js and use in python scripts

Question

I am setting an env variable in node js app: process.env.data = "data-env";
Acessing the same env variable in my python script using : print(os.environ["data"])

but getting error throw err;
        ^

Error: KeyError: 'data'
    at PythonShell.parseError (H:\NodeJS\node_modules\python-shell\index.js:184:17)
    at terminateIfNeeded (H:\NodeJS\node_modules\python-shell\index.js:98:28)
    at ChildProcess.<anonymous> (H:\NodeJS\node_modules\python-shell\index.js:89:9)
    at emitTwo (events.js:126:13)
    at ChildProcess.emit (events.js:214:7)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:198:12)
    ----- Python Traceback -----
    File "script.py", line 5, in <module>
      print(os.environ["data"])
    File "C:\Program Files\Anaconda3\lib\os.py", line 725, in __getitem__
      raise KeyError(key) from None

Using below code from nodeJs to run py script

var PythonShell = require('python-shell');
var myPythonScriptPath = './script.py';
var pyshell = new PythonShell(myPythonScriptPath);


pyshell.on('message', function (message) {
    // received a message sent from the Python script (a simple "print" statement)
    console.log(message);
});

// end the input stream and allow the process to exit
pyshell.end(function (err) {
    if (err){
        throw err;
    };

    console.log('finished');
});

am i doing something wrong?

laika · Accepted Answer · 2018-06-03 19:28:25Z

3

Modifying process.env alters environment variables for the current process and (optionally) child processes.

So, unless you are starting your Python script from the Node.js app, environment variables set in the Node.js app wouldn't be accessible from Python script.

EDIT:

PythonShell accepts second parameter options, which you can use to propagate environment variables down to the child process.

var pyshell = new PythonShell(myPythonScriptPath, {
  env: process.env,
});

edited Jun 3, 2018 at 19:28

answered Jun 3, 2018 at 19:16

laika

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1 Comment

Prabhat Mishra Over a year ago

i am running py script from nodejs module only...please check the updated code in the question...

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