s3.getObject().createReadStream() : How to catch the error?

Question

I am trying to write a program to get a zip file from s3, unzip it, then upload it to S3. But I found two exceptions that I can not catch. 1. `StreamContentLengthMismatch: Stream content length mismatch. Received 980323883 of 5770104761 bytes.` This occurs irregularly. 2. `NoSuchKey: The specified key does not exist.` This happens when I input the wrong key. When these two exceptions occur, this program crashes. I'd like to catch and handle these two exceptions correctly. I want to prevent a crash. ``` const unzipUpload = () => { return new Promise((resolve, reject) => { let rStream = s3.getObject({Bucket: 'bucket', Key: 'hoge/hoge.zip'}) .createReadStream() .pipe(unzip.Parse()) .on('entry', function (entry) { if(entry.path.match(/__MACOSX/) == null){ // pause if(currentFileCount - uploadedFileCount > 10) rStream.pause() currentFileCount += 1 var fileName = entry.path; let up = entry.pipe(uploadFromStream(s3,fileName)) up.on('uploaded', e => { uploadedFileCount += 1 console.log(curren…

Accepted Answer

If you'd like to catch the `NoSuchKey` error thrown by `createReadStream` you have 2 options:

- Check if key exists before reading it.

- Catch error from stream

First:

```
s3.getObjectMetadata(key)
  .promise()
  .then(() => {
    // This will not throw error anymore
    s3.getObject().createReadStream();
  })
  .catch(error => {
    if (error.statusCode === 404) {
      // Catching NoSuchKey
    }
  });
```

The only case when you won't catch error if file was deleted in a split second, between parsing response from `getObjectMetadata` and running `createReadStream`

Second:

```
s3.getObject().createReadStream().on('error', error => {
    // Catching NoSuchKey & StreamContentLengthMismatch
});
```

This is a more generic approach and will catch all other errors, like network problems.

s3.getObject().createReadStream() : How to catch the error?

Solution

Problem