Allow User model to be reloaded in development

[derekprior]

When a user_model is configured in a Clearance initializer, a reference
to that class is immediately saved off. If that class is changed, Clearance
will not know to automatically reload the class as Rails does automatically
for classes in development.

This change introduces a to_prepare block to the Engine that is
responsible for forcing the configured user class to be reloaded.
to_prepare runs once per request in development and only at startup in
other environments.

[jessieay]

> ::User.to_s.constantize
=> User (call 'User.connection' to establish a connection)
>::User
=> User (call 'User.connection' to establish a connection)

since these return the same value, do we need to to_s and constantize?

[derekprior]

Yes, we basically have to force Ruby to re-look-up the constant, which is what we accomplish with constantize from a string. In an actual application running in development mode, if you make changes to the user class, the reference saved by clearance won't actually be the same class that you get with this constantize dance.

As an added benefit (perhaps) this also is more permissive in configuration as users could pass a string or symbol which would still be constantized properly.

[jessieay]

Thanks for the explanation.

[sanderhahn]

Nice! :)

Nitpicking: Rails::Railtie::Configuration#to_prepare defines generic callbacks to run before #after_initialize (not necessarily on every request). The ActionDispatch::Reloader#to_prepare callbacks are run before each request.

[derekprior]

The ActionDispatch::Reloader#to_prepare callbacks are run before each request.

That seems to be the context we're in inside that to_prepare block for the Engine.

[sanderhahn]

You are calling the config.to_prepare in a class extending the Railtie::Engine. That would be: http://api.rubyonrails.org/classes/Rails/Railtie/Configuration.html#method-i-to_prepare. When i was experimenting i found that the reload triggered on every model class change but not necessarily on every request.

[sanderhahn]

Was not sure how to test if reloading was working and looked over the engine. This spec tests if the callback has been configured, which might be enough if you can rely on Rails to properly call them:

  describe "#reload_user_model" do
    it "expect reload_user_model to be called on framework reload" do
      expect(Clearance::Engine.config.to_prepare_blocks).to include(&:reload_user_model)
    end
  end

[derekprior]

I thought about that too. At that point I'm just guarding against someone deleting the to_prepare block. I wouldn't be testing actual behavior. I'm hopeful people will read documentation or git history for the impacted lines and think that's higher value than this particularl test.

[derekprior]

It seems my tests for reload_user_model are non-deterministic, so I'll need to spend a bit more time here.