Using async function to make await call

[dawadam]

Feature Proposal

Using async function to make await call.

Feature Use Case

const fs = require('fs');
const csv = require('csv-parser');

fs.createReadStream('file.csv')
  .pipe(csv())
  .on('data', async (data) => {
    await myAsyncFunction(data);
  })
  .on('end', async () => {
    await myAsyncFunctionEndOfRead();
  });

[dawadam]

Alternative can be (thanks ChatGPT) :

const fs = require('fs');
const csv = require('csv-parser');

async function processLine(line) {
  return new Promise((resolve, reject) => {
    // Votre traitement asynchrone des données de la ligne
    setTimeout(() => {
      console.log(line);
      resolve();
    }, 1000);
  });
}

async function processCsvFile(filePath) {
  return new Promise((resolve, reject) => {
    const stream = fs.createReadStream(filePath).pipe(csv());
    stream.pause();
    stream.on('data', (line) => {
      stream.pause();
      processLine(line)
        .then(() => {
          stream.resume();
        })
        .catch((err) => {
          reject(err);
        });
    });
    stream.on('end', () => {
      console.log('Fin du traitement du fichier CSV.');
      resolve();
    });
    stream.on('error', reject);
    stream.resume();
  });
}

processCsvFile('path/to/file.csv')
  .then(() => {
    console.log('Traitement terminé.');
  })
  .catch((err) => {
    console.error('Une erreur est survenue :', err);
  });

[agustinv]

@dawadam you want to modify the promise to:

processLine(line)
        .then(() => {
           if(stream.readableEnded) {
                console.log('Fin du traitement du fichier CSV.')
                resolve();
              } else {
                stream.resume();
              } 
        })
        .catch((err) => {
          reject(err);
        });

Otherwise you return before the last row's promise resolves!

[ChuckJonas]

Would it be better to use a stream Transform?

https://stackoverflow.com/questions/36662113/node-js-can-you-use-asynchronous-functions-from-within-streams

[markg85]

I have spend SO MUCH TIME getting this to work and pulling my hair out when it didn't work.. Then finding this thread with the (AI geerated code.. for f**** sake). Yeah, now it works.

Another place said that csv-parser is a bit naughty here causing the whole issue to begin with.

Anyhow, i'm happy i found this solution. Can i have my wasted hours back now? 😉