如何在Rails中访问模型上的当前主机和端口？

Question

I am facing the following problem:

I am doing a Rails 4 webapp and we are using paperclip for profile images. If the user does not upload an image we provide a default one (like the facebook silhouette placeholder). So as paperclip eases handling default images, we are doing the following in the Profile model:

class Profile < ActiveRecord::Base
  belongs_to :user
  has_attached_file :image, :styles => { :medium => "300x300", :thumb => "100x100" }, :default_url => "assets/profiles/:style/placeholder.gif"
end

The big problem is that I need the complete URL of the image and NOT only the path so I am struggling to get the host and port before that path. Using action view helpers there did not help ( asset_url helper)

I was thinking in initializing some constant or configuration or environment variable per environment. Will it be correct? Any other suggestions?

EDIT: I forgot to mention this: The resource (Profile) may have a custom picture or a default one. When it has a custom image, we store it in Amazon S3 and in that case profile.image.url returns full URL. In the other case, when it has not a custom picture it has a default image stored in app/assets/images and in that case profile.image.url returns just the path. I would like that the method image.url consistently return full URLs. – flyer88 just now edit

Answer 1

If, as you mention in your comment, you are providing an API endpoint, it might make more sense to determine the host, port, etc. in the controller. Something like this:

# routes.rb
get "/profile/:id" => "api#profile"

# profile.rb
def image_url_or_default request
  if image
    "#{request.protocol}#{request.host_with_port}#{image.url}"
  else
    "http://s3.amazon.com/my_bucket/default.jpg"
  end
end

# api_controller.rb
def profile
  profile = Profile.find params[:id]
  render text:profile.image_url_or_default(request)
end

profile.image.url will be the full URL of the image.