Epic debugging thread and metaprogramming madness in rails_admin

glebm · November 15, 2016, 5:40am

“Magic” is officially a swear word.

github.com/thredded/thredded

Thredded doesn't work alongside rails_admin

opened 10:26AM - 04 May 16 UTC

closed 07:00PM - 15 Nov 16 UTC

StefanDorresteijn

bug

Hey guys, I'm using Thredded alongside [Rails_admin](https://github.com/sferik/…rails_admin) and there are a couple issues. First of all, the thredded policies don't have a rails_admin? function so you can't manage the forum's data from the admin panel. It's pretty easy to copy over the policies and overwrite them but it'd be easier for the policies to already have this functionality. Then if you've decided to simply exclude the policies from rails_admin, the Thredded initializer settings get reset whenever you open rails_admin. The only fix I've found for that is making sure that every single model that Thredded uses is being ignored by RailsAdmin. Not the cleanest option. Thanks, Stefan

TLDR version:

github.com/railsadminteam/rails_admin

Rails Admin loads every single file in autoload paths!

opened 05:28AM - 15 Nov 16 UTC

closed 03:01AM - 20 Mar 17 UTC

glebm

Every single file in `autoload_paths` is eagerly loaded by Rails admin. Below, I…'ll explain how this happens, why this shouldn't happen, and will propose a solution. I came across this when trying to figure a bizarre issue in Thredded + rails_admin compatibility: https://github.com/thredded/thredded/issues/280. ## How does this happen? Here is what RailsAdmin tries to load, [lib/rails_admin/config.rb#L322](https://github.com/sferik/rails_admin/blob/ffa30e0563e86a91bf88a312911b77d1bfffc2dc/lib/rails_admin/config.rb#L322): ```ruby def viable_models included_models.collect(&:to_s).presence || begin @@system_models ||= # memoization for tests ([Rails.application] + Rails::Engine.subclasses.collect(&:instance)).flat_map do |app| (app.paths['app/models'].to_a + app.config.autoload_paths).collect do |load_path| Dir.glob(app.root.join(load_path)).collect do |load_dir| Dir.glob(load_dir + '/**/*.rb').collect do |filename| # app/models/module/class.rb => module/class.rb => module/class => Module::Class lchomp(filename, "#{app.root.join(load_dir)}/").chomp('.rb').camelize end end end end.flatten.reject { |m| m.starts_with?('Concerns::') } # rubocop:disable MultilineBlockChain end end ``` It loads these by calling constantize in [lib/rails_admin/abstract_model.rb#L13-L25](https://github.com/sferik/rails_admin/blob/9e1c66ee036c640ac1b65aab35947c2ebd2671ef/lib/rails_admin/abstract_model.rb#L13-L25): ```ruby def all(adapter = nil) @@all ||= Config.models_pool.collect { |m| new(m) }.compact adapter ? @@all.select { |m| m.adapter == adapter } : @@all end alias_method :old_new, :new def new(m) m = m.constantize unless m.is_a?(Class) (am = old_new(m)).model && am.adapter ? am : nil rescue LoadError, NameError puts "[RailsAdmin] Could not load model #{m}, assuming model is non existing. (#{$ERROR_INFO})" unless Rails.env.test? nil end ``` ### Why this shouldn't happen? If something is in `autoload_paths`, it doesn't mean it can or should *always* be loaded. Rails explicitly makes this distinction with `eager_load`. E.g. if I'm developing a Rails engine, I might want to add `lib` to autoload paths (to ease the development of the engine), but that doesn't mean I want to eagerly load ruby files in `lib/generators/templates`! ### Proposed solution There are a few options here: 1. Remove `app.config.autoload_paths` from the files RailsAdmin tries to autoload. Only load things from `app/models` directories. 2. Replace `app.config.autoload_paths` with `app.paths.eager_load`. 3. Stop messing with the loading system! Just include a module into the base class! 3 is ideal but is also the most effort and I don't have the time. 1 breaks backwards compatibility. So I'll send a PR for 2 for now. Perhaps one day somebody can do 3. @mshibuya @bbenezech @sferik