Rails helper method that determines if an asset exists

application.html.haml

- if asset_exists? "#{params[:controller]}.css"
  = stylesheet_link_tag params[:controller]

- if asset_exists? "#{params[:controller]}.js"
  = javascript_include_tag params[:controller]

application_helper.rb

# Returns true if an asset exists in the Asset Pipeline, false if not.
def asset_exists?(path)
  begin
    pathname = Rails.application.assets.resolve(path)
    return !!pathname # double-bang turns String into boolean
  rescue Sprockets::FileNotFound
    return false
  end
end

Asset Exists?

Helper method that returns true if an asset exists in the Rails asset pipeline, false if not.

Useful for...

If you want to include page specific CSS based on the current controller, but your don't want to include a CSS link if the asset file doesn't exist for the current controller.

Possibly more efficient: Rails.application.assets.find_asset(path).nil?

With Rails 5 / Sprockets 3.7 this works too:

def asset_exists?(path)
  Rails.application.assets.resolve(path).present? 
end

The resolve method will return nil, whereas resolve! will throw an exception.