app/controllers/active_storage/variants_controller.rb
require "active_storage/variant"
# Take a signed permanent reference for a variant and turn it into an expiring service URL for download.
# Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
# security-through-obscurity factor of the signed blob and variation reference, you'll need to implement your own
# authenticated redirection controller.
class ActiveStorage::VariantsController < ActionController::Base
def show
if blob = find_signed_blob
redirect_to ActiveStorage::Variant.new(blob, decoded_variation).processed.service_url(disposition: disposition_param)
else
head :not_found
end
end
private
def find_signed_blob
ActiveStorage::Blob.find_signed(params[:signed_blob_id])
end
def decoded_variation
ActiveStorage::Variation.decode(params[:variation_key])
end
def disposition_param
params[:disposition].in?(%w(inline attachment)) ? params[:disposition] : 'inline'
end
end