Carrierwave upload and access file on S3 - ruby-on-rails

Question

I am struggling to access files on S3 with Carrierwave.
In my uploader file doc_uploader.rb I have the following code
storage :file
def store_dir
"uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
end
to uplooad "doc" model defined as follow
class Doc < ActiveRecord::Base
belongs_to :user
mount_uploader :doc, DocUploader
end
To access the uploaded file I have the following line of code in a controller
#doc = current_user.docs.order("created_at").last #last file uploaded by user
io = open("#{Rails.root}/public" + #doc.doc.url)
Everything works perfectly locally. Now I want to move my file to S3 in the uploader I use fog and replace
storage :file
by
storage :fog
I adjust my config file carrierwave.rb and uploading works perfectly. However, to access the file I try to use
#doc = current_user.docs.order("created_at").last
io = open("#{#doc.doc.url}")
and I get the following error
No such file or directory # rb_sysopen - /uploads/doc/doc/11/the_uploaded_file.pdf
Could anyone give me the right syntax to access the file on S3 please? Thanks.

Answer 1

When accessing the asset through the console, it gives you only the path, you might need to append the protocol & host to the #doc.doc.url, something like:
io = open("http://example.com#{#doc.doc.url}")
Or you can set the asset url on the environment you need to, but this is not really necessary:
config.asset_host = 'http://example.com'
This only applies if you are using the console, on any web view this will not apply, carrierwave seems to handle it