How to specify a prefix when uploading to S3 using activestorage's direct upload? - ruby-on-rails

Question

With a standard S3 configuration:
AWS_ACCESS_KEY_ID: [AWS ID]
AWS_BUCKET: [bucket name]
AWS_REGION: [region]
AWS_SECRET_ACCESS_KEY: [secret]
I can upload a file to S3 (using direct upload) with this Rails 5.2 code (only relevant code shown):
form.file_field :my_asset, direct_upload: true
This will effectively put my asset in the root of my S3 bucket, upon submitting the form.
How can I specify a prefix (e.g. "development/", so that I can mimic a folder on S3)?

Answer 1

2022 update: as of Rails 6.1 (check this commit), this is actually supported:
user.avatar.attach(key: "avatars/#{user.id}.jpg", io: io, content_type: "image/jpeg", filename: "avatar.jpg")

Answer 2

My current workaround (at least until ActiveStorage introduces the option to pass a path for the has_one_attached and has_many_attached macros) on S3 is to implement the move_to method.
So I'm letting ActiveStorage save the image to S3 as it normally does right now (at the top of the bucket), then moving the file into a folder structure.
The move_to method basically copies the file into the folder structure you pass then deletes the file that was put at the root of the bucket. This way your file ends up where you want it.
So for instance if we were storing driver details: name and drivers_license, save them as you're already doing it so that it's at the top of the bucket.
Then implement the following (I put mine in a helper):
module DriversHelper
def restructure_attachment(driver_object, new_structure)
old_key = driver_object.image.key
begin
# Passing S3 Configs
config = YAML.load_file(Rails.root.join('config', 'storage.yml'))
s3 = Aws::S3::Resource.new(region: config['amazon']['region'],
credentials: Aws::Credentials.new(config['amazon']['access_key_id'], config['amazon']['secret_access_key']))
# Fetching the licence's Aws::S3::Object
old_obj = s3.bucket(config['amazon']['bucket']).object(old_key)
# Moving the license into the new folder structure
old_obj.move_to(bucket: config['amazon']['bucket'], key: "#{new_structure}")
update_blob_key(driver_object, new_structure)
rescue => ex
driver_helper_logger.error("Error restructuring license belonging to driver with id #{driver_object.id}: #{ex.full_message}")
end
end
private
# The new structure becomes the new ActiveStorage Blob key
def update_blob_key(driver_object, new_key)
blob = driver_object.image_attachment.blob
begin
blob.key = new_key
blob.save!
rescue => ex
driver_helper_logger.error("Error reassigning the new key to the blob object of the driver with id #{driver_object.id}: #{ex.full_message}")
end
end
def driver_helper_logger
#driver_helper_logger ||= Logger.new("#{Rails.root}/log/driver_helper.log")
end
end
It's important to update the blob key so that references to the key don't return errors.
If the key is not updated any function attempting to reference the image will look for it in it's former location (at the top of the bucket) rather than in it's new location.
I'm calling this function from my controller as soon as the file is saved (that is, in the create action) so that it looks seamless even though it isn't.
While this may not be the best way, it works for now.
FYI: Based on the example you gave, the new_structure variable would be new_structure = "development/#{driver_object.image.key}".
I hope this helps! :)

Answer 3

Thank you, Sonia, for your answer.
I tried your solution and it works great, but I encountered problems with overwriting attachments. I often got IntegrityError while doing it. I think, that this and checksum handling may be the reason why the Rails core team don't want to add passing pathname feature. It would require changing the entire logic of the upload method.
ActiveStorage::Attached#create_from_blob method, could also accepts an ActiveStorage::Blob object. So I tried a different approach:
Create a Blob manually with a key that represents desired file structure and uploaded attachment.
Attach created Blob with the ActiveStorage method.
In my usage, the solution was something like that:
def attach file # method for attaching in the model
blob_key = destination_pathname(file)
blob = ActiveStorage::Blob.find_by(key: blob_key.to_s)
unless blob
blob = ActiveStorage::Blob.new.tap do |blob|
blob.filename = blob_key.basename.to_s
blob.key = blob_key
blob.upload file
blob.save!
end
end
# Attach method from ActiveStorage
self.file.attach blob
end
Thanks to passing a full pathname to Blob's key I received desired file structure on a server.

Answer 4

Sorry, that’s not currently possible. I’d suggest creating a bucket for Active Storage to use exclusively.

Answer 5

The above solution will still give IntegrityError, need to use File.open(file). Thank Though for idea.
class History < ApplicationRecord
has_one_attached :gs_history_file
def attach(file) # method for attaching in the model
blob_key = destination_pathname(file)
blob = ActiveStorage::Blob.find_by(key: blob_key.to_s)
unless blob
blob = ActiveStorage::Blob.new.tap do |blob|
blob.filename = blob_key.to_s
blob.key = blob_key
#blob.byte_size = 123123
#blob.checksum = Time.new.strftime("%Y%m%d-") + Faker::Alphanumeric.alpha(6)
blob.upload File.open(file)
blob.save!
end
end
# Attach method from ActiveStorage
self.gs_history_file.attach blob
end
def destination_pathname(file)
"testing/filename-#{Time.now}.xlsx"
end
end