Cache warmer for Jbuilder-based JSON views

_partial.jbuilder

json.cache! model.cache_key do
  json.(model, *%i(id name description created_at super_long_running_helper_method))
  json.foo foo # 'bar'
  # ...
end

cache_warmer.rb

# Get about a 16-layer stack trace without this. Yes, there's probably a right way, but inheritance!
class WarmerView < ActionView::Base
  def view_cache_dependencies
    []
  end
end

# A little less secret sauce next time. If you've properly set up caching, the sending the `warm` method will either render your view from the cache, or warm the cache. Add any variables/objects used in your view to the :locals option.
class CacheWarmer
  def warm(models)
    models.each do |model|
      view.render(file: path_to_partial, locals: {model: model, foo: 'bar'})
    end
  end

  private
    def path_to_partial
      @path_to_partial ||= 'path_to/_partial.jbuilder'
    end

    def view
      return @view if @view
      @view = WarmerView.new(view_paths, {})
      @view.controller = controller
      @view
    end

    def view_paths
      controller.view_paths
    end

    def controller
      @controller ||= ApplicationController
    end

    def controller_instance
      @controller_instance ||= controller.new
    end
end

development.rb

DemoApp::Application.configure do
  # ...
  config.action_controller.perform_caching = true
  config.cache_store = :dalli_store
  # ...
end