"respond_with" via responders ignores JavaScript redirections

[glennfu]

When rendering a form with remote: true, one can replace the form with an error-rendered state via AJAX. However, using the very popular "responders" conventions, like Devise does, you find that the success response looks like:

respond_with resource, location: after_sign_up_path_for(resource)

while the error response looks like

respond_with resource

The problem here being that the turbolinks-rails handling of the redirection in the success case never happens. In fact, no attempt at redirection is made. It simply tries to render a JS template for the action.

I'm not sure if a fix really belongs inside turbolinks-rails, but this issue is of course specific to turbolinks-rails. So if anyone else is pondering about the same problem, here's a simple fix:

# config/initializers/responders.rb
module ActionController
  class Responder

    # Default implementation of `to_js` is just `default_render` but if there's no errors and
    # we pass a location then I expect to be redirected via Turbolinks JS
    def to_js
      if !has_errors? && options[:location].present?
        redirect_to options[:location]
      else
        default_render
      end
    end

  end
end