如何在 Node.js 中同步运行 Python 脚本？

Question

我通过python-shell在 Node.js 中运行以下 Python 脚本：

import sys
import time
 x=0
 completeData = "";
 while x<800:
  crgb =  ""+x;
  print crgb
  completeData = completeData + crgb + "@";
  time.sleep(.0001)
  x = x+1
  file = open("sensorData.txt", "w")
  file.write(completeData)
  file.close()
  sys.stdout.flush()
else:
 print "Device not found\n"

我对应的 Node.js 代码是：

var PythonShell = require('python-shell');

PythonShell.run('sensor.py', function (err) {
    if (err) throw err;
    console.log('finished');
});
console.log ("Now reading data");

输出是：

Now reading data
finished

但预期输出是：

finished 
Now reading data

Node.js 无法同步执行我的 Python 脚本，它首先执行PythonShell.run函数之后的所有代码，然后执行PythonShell.run 。 如何先执行PythonShell.run然后执行以下代码？ 任何帮助将不胜感激...这是紧急情况，请！

Answer 1

由于这是异步的，添加一个结束回调（在文档中找到）而不是顶层的指令

// end the input stream and allow the process to exit 
pyshell.end(function (err) {
  if (err) throw err;
  console.log ("Now reading data");
});

Answer 2

我遇到了同样的问题，并通过在其中使用PythonShell.run方法做出承诺来解决它。 然后，您只需等待该承诺，您的代码就会同步运行。

承诺方法：

RunPythonScript: function(scriptPath, args, pythonFile){
  let options = {
    mode: 'text',
    pythonPath: 'python',
    pythonOptions: [], 
    scriptPath: scriptPath,
    args: args,
  };

  return new Promise((resolve,reject) =>{
    try{
      PythonShell.run(pythonFile, options, function(err, results) {
        if (err) {console.log(err);}
        // results is an array consisting of messages collected during execution
        console.log('results', results);
        resolve();          
      }); 
    }
    catch{
      console.log('error running python code')
      reject();
    }
  })
},

然后，您等待承诺：

await RunPythonScript(YOURscriptPath,YOURargsScript,YOURpythonFile); 

Answer 3

它对我有用：

let {PythonShell} = require('python-shell');

var options = {
    mode:           'text',
    pythonPath:     'python',
    pythonOptions:  [],
    scriptPath:     '',
    args:           []
};

async function runTest()
{
    const { success, err = '', results } = await new Promise(
        (resolve, reject) =>
        {
            PythonShell.run('hello.py', options,
                function (err, results)
                {
                    if (err)
                    {
                        reject({ success: false, err });
                    }

                    console.log('PythonShell results: %j', results);

                    resolve({ success: true, results });
                }
            );
        }
    );

    console.log("python call ends");

    if (! success)
    {
        console.log("Test Error: " + err);
        return;
    }

    console.log("The result is: " + results);

    // My code here

    console.log("end runTest()");
}

console.log('start ...');

runTest();

console.log('... end main');

结果是：

start ...
... end main
PythonShell results: ["Hello World!"]
python call ends
The result is: Hello World!
end runTest()

Answer 4

 export default { data () { return { } }, method: { callfunction () { console.log ("Now reading data"); }, pyth (){ var PythonShell = require('python-shell'); var vm = this; //save the object (this) in variable vm to use inside pythonshell.run PythonShell.run('sensor.py', function (err) { if (err) throw err; console.log('finished'); vm.callfunction(); }); } } }