How to access 'layout' of parent controller?

Question

In one of my controllers I want to change the layout given some condition, and otherwise keep the default layout used by the parent ApplicationController (was "application" initially, but I'm trying some others now). Tried accessing the "layout" using alias_method but it doesn't seem to work. My code:

class SomeController < ApplicationController
  alias_method :parent_layout, :layout
  layout :some_layout

  def some_layout
    if some_condition
      "new_layout"
    else
      :parent_layout
    end
  end
end

This gives an error:

ActionController::RoutingError (undefined method `layout' for class `SomeController'):
  app/controllers/some_controller.rb:6:in `alias_method'
  app/controllers/some_controller.rb:6:in `<class:SomeController>'
  app/controllers/some_controller.rb:3:in `<top (required)>'

Answer 1

It looks like you have a bunch of options. Check out the docs here (search for "finding layouts") http://guides.rubyonrails.org/layouts_and_rendering.html

Some possibilities, depending on just how complex you need it to be:

# Proc-based
class ProductsController < ApplicationController
  layout Proc.new { |controller| controller.request.xhr? ? "popup" : "application" }
end

# Route based, :except and :only
class ProductsController < ApplicationController
  layout "product", except: [:index, :rss]
end

# Method-based
class OldArticlesController < SpecialArticlesController
  layout false

  def show
    @article = Article.find(params[:id])
  end

  def index
    @old_articles = Article.older
    render layout: "old"
  end
  # ...
end

I'm not sure how your code is structured but it looks like the first could work for you:

class SomeController < ApplicationController
  layout Proc.new { |controller| controller.some_condition? ? "new_layout" : "application" }
end