如何从 NodeJs 调用 python 脚本

IT技术 javascript python node.js python-2.7 raspberry-pi
2021-03-04 23:45:22

我需要在 NodeJs 中调用这个 python 脚本。

读取文件

#!/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

测试.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);
});

但是当我运行这段代码时,我在 Node 端没有看到任何东西。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)

因为我只是用 while 循环运行,它只有打印语句,然后它就可以工作了。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

测试工具

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

6个回答

有多种方法可以做到这一点。

  • 第一种方法是做 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

您可以使用 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 node 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,您可以在其中找到使用子进程的示例 - How to invoke external scripts/programs from node.js

还有一些参考资料 - 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/

你好@Tejus Prasad,我想使用第一种方式。但是我的 Node JS 代码是 AWS Lambda 函数,而我的 Python 代码保存在树莓派中。我的问题是我应该在哪里使用 Python shell。如果在 AWS 中该怎么做?
2021-05-19 23:45:22
  • 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)

采用微服务方法。将 Python 脚本作为 HTTP REST API 服务托管。从 node.js 使用 API - 您不需要集成这些技术;它不可扩展。

有时是的,这取决于上下文
2021-04-21 23:45:22
只有当 python 输出是可序列化的数据时,这才是正确的吗?是否可以使用 JS 代码以某种方式通知 python 更新 API,然后在完成后访问更新的 API?
2021-04-23 23:45:22

好吧,你可以像这样node.js运行python脚本使用child_process.spawn这是在 node.js 库中构建的

router.get('/', (req, res) => {
    const {spawn} = require('child_process');
    const path = require('path');
    function runScript(){
        return spawn('python', [
              path.join(__dirname, '../../scripts/myscript.py'),
              '-some_arg',
              '--another_arg',
        ]);
    }
    const subprocess = runScript();
    // print output of script
    subprocess.stdout.on('data', (data) => {
            console.log(`data:${data}`);
    });
    subprocess.stderr.on('data', (data) => {
           console.log(`error:${data}`);
    });
    subprocess.stderr.on('close', () => {
               console.log("Closed");
    });
    // const subprocess = runScript()
    res.set('Content-Type', 'text/plain');
    subprocess.stdout.pipe(res);
    subprocess.stderr.pipe(res);
});

如果您想避免包管理器/膨胀,请考虑编写一个 shell 脚本函数来运行 python,将结果本地流式传输到 txt 文件,收集并发送,例如使用 http:

    const { exec } = require("child_process");
    
    function runShellScript(script, callback) {
        exec(script, (error, stdOut, stderr) => {
            
            var result = {status: true};
            
            if (error) {
                result.status = false;
                result.error = error.message;
            }
            if (stderr) {
                result.status = false;
                result.stderr = stderr;
            }
    
            if(stdOut){
                result.result = stdOut;
            }
            
    
            callback(result);
        });
    }
    
    runShellScript("python3 myscript.py >> output.txt", function(res) {
        console.log(res);
fs.readFileSync('output.txt');
    });