Promise.all is returning undefined

Question

When I asynchronously map an array, Promise.all was supposed to make the function wait until all the promises are resolved. However, Promise.all shows as undefined. Here is my code. Please can someone tell me what I am doing wrong? Thanks.

router.get("/vehicle_reports/interior-pictures", auth, async (req, res) => {

  const fileKeysObj = await Report.findOne({ orderId: req.params.jobId }, {
    "vehicleInterior": 1
  })
  const fileKeysArray = fileKeysObj.interior
  console.log("fileKeysArray: ", fileKeysArray);

  //Retrieve the files from S3
  const files = fileKeysArray.map(async (item) => {
    const params = {
      Bucket: process.env.AWS_BUCKET_NAME,
      Key: item.fileKey
    }
    await s3.getObject(params, async (err, data) => {
      if (err) {
        throw new Error()
      }
      else {
        const base64Data = base64Arraybuffer.encode(data.Body)
        const contentType = data.ContentType
        const fileName = item.fileName
        return { base64Data, contentType, fileName }
      }
    })
  })
  console.log( files) //Pending promise
  await Promise.all(files) 
  console.log( files) //Undefined
  res.send(files) //Sends empty array
})

Answer 1

Replace the inside of the map call to look like this.

const params = {
  Bucket: process.env.AWS_BUCKET_NAME,
  Key: item.fileKey
}
return new Promise((res, rej) => {
    s3.getObject(params, async (err, data) => {
      if (err) {
        rej('FAILED');
      } else {
        const base64Data = base64Arraybuffer.encode(data.Body)
        const contentType = data.ContentType
        const fileName = item.fileName
        res( { base64Data, contentType, fileName });
      }
    })

});