How can I customize the active admin layout?

The active admin layout is not actually defined as a layout file, but is generated programatically. Placing a custom layout in the layout directory will therefore not actually override the default layout.

You can, however, monkey-patch or duck-punch the active admin layout methods inside your application.

The following will add an ie-specific stylesheet to the header:

module ActiveAdmin  module Views    module Pages      class Base < Arbre::HTML::Document        alias_method :original_build_active_admin_head, :build_active_admin_head unless method_defined?(:original_build_active_admin_head)        def build_active_admin_head          within @head do            meta :"http-equiv" => "Content-type", :content => "text/html; charset=utf-8"            insert_tag Arbre::HTML::Title, [title, active_admin_application.site_title].join(" | ")            active_admin_application.stylesheets.each do |path|              link :href => stylesheet_path(path), :media => "screen", :rel => "stylesheet", :type => "text/css"            end            active_admin_application.javascripts.each do |path|              script :src => javascript_path(path), :type => "text/javascript"            end            text_node csrf_meta_tag            text_node "<!--[if lt IE 7]>            <link rel=\"stylesheet\" type=\"text/css\" media=\"all\" href=\"admin_ie7.css\ />            <![endif] -->".html_safe          end        end      end    end  endend

Clearly an ugly solution.

When a view is defined in a gem AND in the rails app, the one defined in the Rails app is served. It's a logic priority.

So if you need to override all or some active admin views, you'll have to copy these in your app and change them as you desire.

Maybe ActiveAdmin does provide a nicer way to do this by now? I don't know.However here would be an example for a bit cleaner patch for that situation, in my example to add the webpacker gems javascript_pack_tag to my admin area.

module MyApp  module ActiveAdmin    module Views      module Pages        module BaseExtension          def build_active_admin_head            super            within @head do              text_node(javascript_pack_tag('application'))            end          end        end      end    end  endendclass ActiveAdmin::Views::Pages::Base < Arbre::HTML::Document  prepend MyApp::ActiveAdmin::Views::Pages::BaseExtensionend