JavaScript 不等到 python 执行完成

Question

I have installed python shell npm and using it to call the python script from node.js. At the end of the python script execution a json file will be written to the local system.

The thing is my javascript is not waiting for the python execution to be completed and trying to read the file that is not yet written. So i am not getting the expected result or getting error. Any help would be very much appreciated. Thanks!

Here is my code:

import * as filePaths from './filePaths';
import * as scriptParameters from './pythonScriptParameters';
import * as constantmessages from './constantMessages';
import * as logger from '../Utilities/logger';
import fs from 'fs';
​
const { PythonShell } = require('python-shell');
​
export async function runManufacturingTest(){
​

PythonShell.run(scriptParameters.scriptFileName, scriptParameters.options, function(err, results) {
    if (err) {
          logger.error(err, '[ config - runManufacturingTest() ]');
      }
      const provisioningresultjson = fs.readFileSync(filePaths.provisioningresults);
      const parsedResult = JSON.parse(provisioningresultjson);
      \\ Rest of the code
​​​}
}

Answer 1

you should Convert callbacks to promise. So you can await the js thread till promise is resolved/rejected.

You can give a try to this.

 export async function runManufacturingTest() { const { success, err = '', results } = await new Promise((resolve, reject) => { PythonShell.run(scriptParameters.scriptFileName, scriptParameters.options, function( err, results ) { if (err) { logger.error(err, '[ config - runManufacturingTest() ]'); reject({ success: false, err }); } resolve({ success: true, results }); }); if (success) { const provisioningresultjson = fs.readFileSync(filePaths.provisioningresults); const parsedResult = JSON.parse(provisioningresultjson); // rest of your Code } }); }