ActiveStorage File Attachment Validation

Question

Is there a way to validate attachments with ActiveStorage? For example, if I want to validate the content type or the file size?

Something like Paperclip\'s approach wou

Answer 1

Copy contents of the ActiveStorage's DirectUploadsController in the app/controllers/active_storage/direct_uploads_controller.rb file and modify the create method. You can add authentication to this controller, add general validations on the file size or mime type, because create method of this controller creates the url for the file to be uploaded. So you can prevent any file upload by controlling size and mime type in this controller.

A simple validation could be:

# ...
def create
  raise SomeError if blob_args[:byte_size] > 10240 # 10 megabytes
  blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
  render json: direct_upload_json(blob)
end
# ...