使用循环生成不同的签名 url (S3)

Question

im having an issue trying to create a list of urls for multipart upload to S3 using lamba, im trying to generate the URLs using a loop in the lambda function, but it only generates 1 and keeps returning that one across all the loop, so at the end i have an array of urls with the same url repeated, it doesnt happen if i call the generateSignedUrl() method multiple times in the code, i mean if instead of calling the for loop to loop 3 times, i use the generateSignedUrl() method 3 times it actually generates 3 different URLs, while the loop generates 1 repeated 3 times.

async function getSignedUrl(key){
    return new Promise((resolve,reject) => {
      let params = { Bucket: bucketName, Key: key };
      s3.getSignedUrl('getObject', params, (err, url) => {
        if (err) reject(err)
        resolve(url);
      })
});
}

async function process(items) {
  for (let item of items) {
    const signedUrl = await getSignedUrl(item.fileName);
    item.url = signedUrl;
  }
  return items;
}


process(result).then(res => {
  console.log(res);
});

Answer 1

Inside your for loop you are declaring signedUrl as a const. This is why the value of the signedUrl is not changing for the items in the for loop and why it is working when you are calling your getSignedURL method explicitly.

Try changing signedUrl to a var.