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

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

1. Check if key exists before reading it.
2. 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.

You need to listen for the emitted error earlier. Your error handler is only looking for errors during the unzip part.

A simplified version of your script.

s3.getObject(params).createReadStream().on('error', (e) => {  // handle aws s3 error from createReadStream}).pipe(unzip).on('data', (data) => {  // retrieve data}).on('end', () => {  // stream has ended}).on('error', (e) => {  // handle error from unzip});

This way, you do not need to make an additional call to AWS to find out if out if it exists.

You can listen to events (like error, data, finish) in the stream you are receiving back. Read more on events

function getObjectStream (filePath) {  return s3.getObject({    Bucket: bucket,    Key: filePath  }).createReadStream()}let readStream = getObjectStream('/path/to/file.zip')readStream.on('error', function (error) {  // Handle your error here.})

Tested for "No Key" error.

it('should not be able to get stream of unavailable object', function (done) {  let filePath = 'file_not_available.zip'  let readStream = s3.getObjectStream(filePath)  readStream.on('error', function (error) {    expect(error instanceof Error).to.equal(true)    expect(error.message).to.equal('The specified key does not exist.')    done()  })})

Tested for success.

it('should be able to get stream of available object', function (done) {  let filePath = 'test.zip'  let receivedBytes = 0  let readStream = s3.getObjectStream(filePath)  readStream.on('error', function (error) {    expect(error).to.equal(undefined)  })  readStream.on('data', function (data) {    receivedBytes += data.length  })  readStream.on('finish', function () {    expect(receivedBytes).to.equal(3774)    done()  })})