How to retrieve reference to AWS::S3::MultipartUpload with ruby - ruby-on-rails

Question

I have a rails app and in a controller action I am able to create a multipart upload like so:
def create
s3 = AWS::S3.new
bucket = s3.buckets["my_bucket"]
key = "some_new_file_name.ext"
obj = bucket.objects[key]
mpu = obj.multipart_upload
render json: {
:id => mpu.id
}
end
so now the client has the multipart upload id and she can upload parts to aws with her browser. I wish to create another action which will assemble the parts once they are done uploading. Something like:
def assemble
s3 = AWS::S3.new
bucket = s3.buckets["my_bucket"]
key = params['key']
bucket.objects[key].multipart_upload.complete
render json: { :status => "all good" }
end
This isn't working though. How do I retrieve a reference to the multipartUpload object or create a new one with the key or id so that I can call the "complete" method on it? Any insight is appreciated

Answer 1

I found this method in the documentation for the Client class and got it to work as follows:
client = AWS::S3::Client.new
# reassemble partsList
partsList = []
params[:partsList].each do |key, pair|
partsList.push pair
end
options = {
:bucket_name => 'my_bucket',
:key => params[:key],
:upload_id => params[:upload_id],
:parts => partsList
}
client.complete_multipart_upload(options)