如何从NodeJs调用python脚本

Question

我需要在NodeJs中调用这个python脚本.

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"

我使用了python-shell,这里是NodeJs代码

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);
});

但是,当我运行此代码时,我没有在Node端看到任何内容.我认为当python脚本达到这个级别时会出现问题.

   (status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)

因为我只使用while循环运行只有print语句然后它工作.之后我尝试了另一种方法来实现这一目标.但是我遇到了与上面相同的问题.这是另一种方法

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...");
 });

任何帮助,将不胜感激

Answer 1

有多种方法可以做到这一点.

• 第一种方式是做 npm install python-shell

这是代码

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

你可以使用发送消息到python shell pyshell.send('hello');

你可以在这里找到API参考 - https://github.com/extrabacon/python-shell

• 第二种方式 - 您可以参考的另一个包是节点python,您必须这样做 npm install node-python

• 第三种方式 - 您可以参考这个问题,在哪里可以找到使用子进程的示例 - 如何从node.js调用外部脚本/程序

还有一些参考文献 - https://www.npmjs.com/package/python

如果你想使用面向服务的架构 - http://ianhinsdale.com/code/2013/12/08/communicating-between-nodejs-and-python/

Answer 2

• 安装 python-shell :- npm install python-shell

  索引.js

  let {PythonShell} = require('python-shell')
  
  function runPy(){
      return new Promise(async function(resolve, reject){
            let options = {
            mode: 'text',
            pythonOptions: ['-u'],
            scriptPath: './test.py',//Path to your script
            args: [JSON.stringify({"name": ["xyz", "abc"], "age": ["28","26"]})]//Approach to send JSON as when I tried 'json' in mode I was getting error.
           };
  
            await PythonShell.run('test.py', options, function (err, results) {
            //On 'results' we get list of strings of all print done in your py scripts sequentially. 
            if (err) throw err;
            console.log('results: ');
            for(let i of results){
                  console.log(i, "---->", typeof i)
            }
        resolve(results[1])//I returned only JSON(Stringified) out of all string I got from py script
       });
     })
   } 
  
  function runMain(){
      return new Promise(async function(resolve, reject){
          let r =  await runPy()
          console.log(JSON.parse(JSON.stringify(r.toString())), "Done...!@")//Approach to parse string to JSON.
      })
   }
  
  runMain() //run main function
  

测试文件

    import sys #You will get input from node in sys.argv(list)
    import json
    import pandas as pd #Import just to check if you dont have pandas module you can comment it or install pandas using pip install pandas

    def add_two(a, b):
        sum = 0
        for i in range(a, b):
            sum += i
        print(sum)  

    if __name__ == "__main__":
        print("Here...!")
        # print(sys.argv)
        j = json.loads(sys.argv[1]) #sys.argv[0] is filename
        print(j)
        add_two(20000, 5000000) #I make this function just to check 
    # So for all print done here you will get a list for all print in node, here-> console.log(i, "---->", typeof i)

Answer 3

采用微服务方法。将 Python 脚本托管为 HTTP REST API 服务。使用 Node.js 中的 API - 您不需要集成技术；它不可扩展。