Rails.application.assets is Nil on Heroku after upgrade sprockets-rails to 3.0.0

问题

I check this command Rails.application.assets in local console it work but in heroku console it return Nil.

but when I rollback to use sprockets-rails 2.3.3 and check Rails.application.assets in heroku console it return value.

what happened?

回答1:

This was the result of a change in sprockets-rails 3. See the issue https://github.com/rails/sprockets-rails/issues/237

You can get around the issue for now by setting config.assets.compile = true in /config/environments/production.rb

回答2:

You might need to change some of your code to be compatible with sprockets-rails 3, please read https://github.com/rails/sprockets/blob/master/UPGRADING.md

回答3:

I solved this by adding an application helper like this:

def image_exists?(path)
    if Rails.env == "development" && Rails.application.assets.find_asset(path)
      return true
    elsif Rails.env == "production" && Rails.application.assets_manifest.assets[path]
      return true
    else
      return false
    end
 end

Then I could check if an image exists by finding the path and running

image_exists?(path)

In my app, usually the path is just the image file name, unless the image is in a subfolder within the images directory.

来源：https://stackoverflow.com/questions/34380753/rails-application-assets-is-nil-on-heroku-after-upgrade-sprockets-rails-to-3-0-0