19

I want to set a class attribute when my Rails app starts up. It requires inspecting some routes, so the routes need to be loaded before my custom code runs. I am having trouble finding a reliable place to hook in.

This works PERFECTLY in the "test" environment:

config.after_initialize do
  Rails.logger.info "#{Rails.application.routes.routes.map(&:path)}"
end

But it doesn't work in the "development" environment (the routes are empty)

For now I seem to have things working in development mode by running the same code in config.to_prepare which I understand happens before every request. Unfortunately using to_prepare alone doesn't seem to work in test mode, hence the duplication.

I'm curious why the routes are loaded before after_initialize in test mode, but not in development mode. And really, what is the best hook for this? Is there a single hook that will work for all environments?

*EDIT*

mu's suggestion of reloading the routes was great. It gave me consistent access to the routes within after_initialize in all environments. For my use case though, I think I still need to run the code from to_prepare as well, since I'm setting a class attribute on a model and the models are reloaded before each request.

So here's what I ended up doing.

[:after_initialize, :to_prepare].each do |hook|
  config.send(hook) do
    User.invalid_usernames += Rails.application.routes.routes.map(&:path).join("\n").scan(/\s\/(\w+)/).flatten.compact.uniq
  end 
end

It seems a bit messy to me. I think I'd rather do something like:

config.after_initialize do
  User.exclude_routes_from_usernames!
end

config.to_prepare do
  User.exclude_routes_from_usernames!
end

But I'm not sure if User is the right place to be examining Rails.application.routes. I guess I could do the same thing with code in lib/ but I'm not sure if that's right either.

Another option is to just apply mu's suggestion on to_prepare. That works but there seems to be a noticeable delay reloading the routes on every request in my dev environment, so I'm not sure if this is a good call, although it's DRY, at least.

config.to_prepare do
  Rails.application.reload_routes!
  User.invalid_usernames += Rails.application.routes.routes.map(&:path).join("\n").scan(/\s\/(\w+)/).flatten.compact.uniq
end
poochenza
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2 Answers2

28

You can force the routes to be loaded before looking at Rails.application.routes with this:

Rails.application.reload_routes!

So try this in your config/application.rb:

config.after_initialize do
  Rails.application.reload_routes!
  Rails.logger.info "#{Rails.application.routes.routes.map(&:path)}"
end

I've done similar things that needed to check the routes (for conflicts with /:slug routes) and I ended up putting the reload_routes! and the checking in a config.after_initialize like you're doing.

mu is too short
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  • Great idea! Turns out we're actually using this for the same thing (I'm updating a `class_attribute` called `User.invalid_usernames` that is used as an exclusion list with `validates_exclusion_of`). I think I still need the to_prepare for development mode though. Without it, it works fine on the first request (now that I'm using your suggestion), but after that I think my `User.invalid_usernames = Set.new` is clobbering it. It sounds like you're only using after_initialize though, so I'm wondering if there is some clever way you got around that? – poochenza Jan 03 '12 at 12:18
  • This answer helped a lot so I'm accepting it although I didn't end up using it (open to criticism if you think I should though!) Here is my full solution, would love your feedback if you have time: http://stackoverflow.com/a/8713207/1126857 – poochenza Jan 03 '12 at 14:32
  • @poochenza: I used `after_initialize` to make sure no new conflicts appeared between releases: if you add a `/pancakes` route and publish two weeks later, you want to know if someone created a "pancakes" user on the production system in the mean time. Then I compare new usernames against the routes as the usernames are created or updated. – mu is too short Jan 04 '12 at 06:40
3

If you're trying to run code in an initializer after the routes have loaded, you can try using the after: option:

initializer "name_of_initializer", after: :add_routing_paths do |app|
  # do custom logic here
end

You can find initialization events here: http://guides.rubyonrails.org/configuring.html#initialization-events

Mieczysław Daniel Dyba
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