TRB to the Max

gistfile1.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'trailblazer-operation'
end
# require "trailblazer-operation"

module Image
  module Operation
    class Attach < Trailblazer::Operation
      step :download
      step :save

      def download(ctx, url:, **)
        ctx[:file] = Object.new # TODO: implement HTTPS download.
      end

      def save(ctx, file:, model:, **)
        model.attach(file)
      end
    end

    class AttachFromAPI < Attach # I wouldn't name it like that, though.
      step :close_tmpfile, after: :save

      # You can simply override the downloading {#download}
      def download(ctx, api_url:, **)
        ctx[:file] = Tempfile.new # TODO: implement API download.
      end

      def close_tmpfile(ctx, file:, **)
        file.close
      end
    end
  end
end

class ARImage
  def attach(*)
    true
  end
end

class Tempfile
  def close
    true
  end
end

# in your controller/script

result = Image::Operation::Attach.call(model: ARImage.new, url: "https://railscasts.sexy/topless.jpg")

puts result.success?
puts result[:model]


result = Image::Operation::AttachFromAPI.call(model: ARImage.new, api_url: "https://api.railscasts.sexy/img/topless.jpg")

puts result.success?
puts result[:model]