I need to call this python script in NodeJs.
Read.py
#!/usr/bin/env python # -*- coding: utf8 -*- import RPi.GPIO as GPIO import MFRC522 import signal continue_reading = True # Capture SIGINT for cleanup when the script is aborted def end_read(signal,frame): global continue_reading print "Ctrl+C captured, ending read." continue_reading = False GPIO.cleanup() # Hook the SIGINT signal.signal(signal.SIGINT, end_read) # Create an object of the class MFRC522 MIFAREReader = MFRC522.MFRC522() # Welcome message print "Welcome to the MFRC522 data read example" print "Press Ctrl-C to stop." # This loop keeps checking for chips. If one is near it will get the UID and authenticate while continue_reading: # Scan for cards (status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL) # If a card is found if status == MIFAREReader.MI_OK: # Get the UID of the card (status,uid) = MIFAREReader.MFRC522_Anticoll() # If we have the UID, continue if status == MIFAREReader.MI_OK: # Print UID print "Card read UID: "+str(uid[0])+","+str(uid[1])+","+str(uid[2])+","+str(uid[3]) # This is the default key for authentication key = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF] # Select the scanned tag MIFAREReader.MFRC522_SelectTag(uid) # Authenticate status = MIFAREReader.MFRC522_Auth(MIFAREReader.PICC_AUTHENT1A, 8, key, uid) # Check if authenticated if status == MIFAREReader.MI_OK: MIFAREReader.MFRC522_Read(8) MIFAREReader.MFRC522_StopCrypto1() else: print "Authentication error"
I used python-shell, here is the NodeJs code for that
Test.js
var PythonShell = require('python-shell'); var options = { scriptPath: '/home/pi/gpio-admin/MFRC522-python/' }; var pyshell = new PythonShell('Read.py',options); pyshell.on('message', function (message) { console.log(message); });
But when I ran this code I didn’t see anything in Node side. I think problem occurs when python script comes to this level.
(status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)
Because I just ran with while loop which has only print statement then it works. After that I tried another way to achieve this. But I got same problem which I have with above.Here is another method
AltTest.js
var python = require('child_process').spawn( 'python', // second argument is array of parameters, e.g.: ["/home/pi/gpio-admin/MFRC522-python/Read.py"] ); var output = ""; python.stdout.on('data', function(){ output += data ; console.log(data); }); python.on('close', function(code){ console.log("Here you are there..."); });
Any help would be appreciated
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Answer
There are multiple ways of doing this.
- first way is by doing
npm install python-shell
and here’s the code
var PythonShell = require('python-shell'); //you can use error handling to see if there are any errors PythonShell.run('my_script.py', options, function (err, results) { //your code
you can send a message to python shell using
pyshell.send('hello');
you can find the API reference here- https://github.com/extrabacon/python-shell
second way – another package you can refer to is node python , you have to do
npm install node-python
third way – you can refer to this question where you can find an example of using a child process- How to invoke external scripts/programs from node.js
a few more references – https://www.npmjs.com/package/python
if you want to use service-oriented architecture – http://ianhinsdale.com/code/2013/12/08/communicating-between-nodejs-and-python/