CODEWITHSUNDEEP
javascriptnode.jsamazon-web-servicesamazon-s3promise
Nicolas
Nicolas

Reputation: 4756

node.js - Combining 2 Promises

I have to create a file upload which stores files in an amazon S3 bucket, and then writes info into a database.

  router.post('/report', upload.single('file'), function(req, res, next) {
    reportService
      .uploadReport(req.body, req.file)
      .then(data => {
        res.send(data);
      })
      .catch(err => {
        res.send(err);
      });
  });

This piece of code handles the call. It triggers the following code.

function uploadReport(report, file) {
  var objectParams = { Bucket: bucketName, Key: file.filename, Body: '' };
  var fs = require('fs');
  var fileStream = fs.createReadStream(file.path);
  fileStream.on('error', function(err) {
    console.log('File Error', err);
  });
  objectParams.Body = fileStream;
  return new Promise((resolve, reject) => {
    s3.putObject(objectParams)
    .promise()
    .then(
      data => {
        resolve(this.addReport(report, data.Location)
          .then(response => resolve(response))
          .catch(err => {
            reject(err);
          })
        );
      },
      err => {
        reject(err);
      }
    );
  });
}

This piece of code uploads the file to my s3 bucket, after the upload is finished, it calls the save report function which writes into the database.

function addReport(report, url) {
  return new Promise((resolve, reject) => {
    reportModel
      .addReport(report, url)
      .then(report => {
        resolve(report);
      })
      .catch(err => {
        reject(err);
      });
  });
}

I know my 2 promises work separately, but combining them into 1 promise doesn't trigger any function.

How can I correctly combine them into 1 promise?

Upvotes: 0

Views: 83

Answers (2)

mr.G
mr.G

Reputation: 19

You will have to return the addReport promise and then resolve/reject the original promise inside the then callback.

Upvotes: 0

zero298
zero298

Reputation: 26878

It looks like you are violating the What is the explicit promise construction antipattern and how do I avoid it?. You are resolving a Promise with a Promise. Instead, you want to just return the Promise:

return s3
    .putObject(objectParams)
    .promise()
    .then(data => this.addReport(report, data.location));

Upvotes: 1

Related Questions