ActionCable + Devise + Pundit + ApplicationController.render - ruby-on-rails

Question

I'm trying to render a template in a ActionJob to be broadcast via ActionCable.
ApplicationController.render(partial: "messages/message", locals: { message: message }, assigns: { current_user: user}).squish
In most instances, this works fine, however some of my templates use Punit for authorization in the view.
<% if policy(message).show? %>
<%= message.body %>
<% end %>
This raises an error when the job is ran.
ActionView::Template::Error: Devise could not find the `Warden::Proxy` instance on your request environment.
A quick Google search reveals this issue: https://github.com/plataformatec/devise/issues/4271
The mentioned in the ticket and links, there is no env['warden'] available because no middleware has executed to add it.
How can I work around this?

Answer 1

As a workaround, this is what I've done:
class ActiveJobController < ActionController::Base
end
In my partial, instead of using the policy helper, I'm doing this
<% if Pundit::PolicyFinder.new(message).policy.new(current_user, message).show? %>
<%= message.body %>
<% end %>
and from my ActiveJob
ActiveJobController.render(partial: "messages/message", locals: { message: message, current_user: user }).squish
This avoids any of the stock Devise and Pundit helpers which references env["warden"]. It isn't ideal but works for now both when rendered in a request and in a job.

Answer 2

Another scalable/maintainable approach is to use a helper or a view library like ViewComponents/cells. This way, you can extract your existing view into a component and parameterize any devise/warden methods called in the view. The advantage of this approach is
The view is easier to test
You can call it from anywhere in your code
There are no coupled dependencies
Example using view helpers
Say you have in app/views/messages/show.html.erb the following
<%= current_user.first_name %>
<%= #message %>
Calling MessagesController.render :show outside the controller will cause an error since access to the request object is not available. Using ViewComponents, we extract the view into its own component
in app/components/message_component.rb
class MessageComponent < ViewComponent::Base
def initialize(user:, message:)
#user = user
#message = message
end
end
in app/components/message_component.html.erb
<%= #user.first_name %>
<%= #message %>
Usage
In app/views/messages/show.html.erb just call
<%= render(MessageComponent.new(message: #message, user: current_user) %>
In ActionCable, call it like so
ApplicationController.render(MessageComponent.new(message: #message, user: current_user)
Since you have access to ActiveRecord models from anywhere in your code, you should be able to fetch #message