Paperclip custom interpolation (aka custom path for AWS S3) - ruby-on-rails

Question

I have three questions related to paperclip and AWS S3.
1) In my model which has paperclip, I have following code:
has_attached_file :attachment,
:url => "/songs/:user_id/:basename.:extension",
:path => "/songs/:user_id/:basename.:extension"
What's the difference between URL and PATH?
2) What is :basename.:extension?
3) Let's say there are two models: User and File. User has many File. Paperclip path and url are configured in File model.
In config/initializers/paperclip.rb, I put below code:
Paperclip.interpolates :user_id do |attachment, style|
attachment.instance.criteria.user_id
end
I confirm that above code is working fine. My file gets saved at songs/5/song.mp3. I would like to save the mp3 file at songs/user_id_5/song.mp3. I tried doing below but it doesn't work.
Paperclip.interpolates :user_id do |attachment, style|
'user_id_' + attachment.instance.criteria.user_id
end
How do I make it as I want to ?

Answer 1

in S3 language path is the Key of your item and url is your s3 endpoint
From docs
url: There are four options for the S3 url. You can choose to have the bucket's name placed domain-style (bucket.s3.amazonaws.com) or
path-style (s3.amazonaws.com/bucket). You can also specify a CNAME
(which requires the CNAME to be specified as :s3_alias_url. You can
read more about CNAMEs and S3 at
docs.amazonwebservices.com/AmazonS3/latest/index.html?VirtualHosting.html
Normally, this won't matter in the slightest and you can leave the
default (which is path-style, or :s3_path_url). But in some cases
paths don't work and you need to use the domain-style
(:s3_domain_url). Anything else here will be treated like path-style.
path: This is the key under the bucket in which the file will be stored. The URL will be constructed from the bucket and the path. This is what you will want to interpolate. Keys should be unique, like filenames, and despite the fact that S3 (strictly speaking) does not support directories, you can still use a / to separate parts of your file name.
you can configure the bucket or url in your config and just pass the path (i.e. where to store the file) when you call the method
config.paperclip_defaults = {
storage: :s3,
s3_credentials: {
bucket: 'mybucket'),
access_key_id: ENV.fetch('AWS_ACCESS_KEY_ID'),
secret_access_key: ENV.fetch('AWS_SECRET_ACCESS_KEY'),
s3_region: 'aws_region_id',
}
}
I don't know
You need string interpolation
Paperclip.interpolates :user_id do |attachment, style|
"user_id_#{attachment.instance.criteria.user_id}"
end