Allow users to globally opt out of automatic lookup

lib/action_controller/serialization.rb

@@ -21,6 +21,10 @@ module ActionController
     end
 
     def get_serializer(resource, options = {})
+      unless options[:serializer] || options[:each_serializer] || ActiveModel::Serializer.config.automatic_lookup
+        return resource
+      end
+
       if !use_adapter?
         warn 'ActionController::Serialization#use_adapter? has been removed. '\
           "Please pass 'adapter: false' or see ActiveSupport::SerializableResource.new"

lib/active_model/serializer/configuration.rb

@@ -20,6 +20,7 @@ module ActiveModel
 
         config.adapter = :attributes
         config.jsonapi_resource_type = :plural
+        config.automatic_lookup = true
       end
     end
   end