Redmine

Hi!

When I start a Rails console in development and at some point run a reload! to reload changes I have just made to the source code, I get a RuntimeError:

> rails console
Loading development environment (Rails 6.1.7)
irb(main):001:0> reload!
Reloading...
Traceback (most recent call last):
        7: from config/initializers/30-redmine.rb:11:in `block in <top (required)>'
        6: from lib/redmine/preparation.rb:163:in `prepare'
        5: from lib/redmine/menu_manager.rb:251:in `map'
        4: from lib/redmine/preparation.rb:164:in `block in prepare'
        3: from lib/redmine/menu_manager.rb:321:in `push'
        2: from lib/redmine/menu_manager.rb:403:in `add'
        1: from lib/redmine/menu_manager.rb:386:in `add_at'
RuntimeError (Child already added)

The source of the error is Redmine::Preparation.prepare, which is called in this to_prepare block in config/initializers/30-redmine.rb:

Rails.application.config.to_prepare do
  I18n.backend = Redmine::I18n::Backend.new
  # Forces I18n to load available locales from the backend
  I18n.config.available_locales = nil

  Redmine::Preparation.prepare
end

The reason for the error is that Rails.application.reloader.reload! correctly runs the prepare callbacks twice, but Redmine::Preparation.prepare does not support being called multiple times.

From https://github.com/rails/rails/pull/28111#issuecomment-285370954:

We already call prepare a thoroughly variable number of times -- if your prepare handler isn't idempotent, you're going to have a bad time.

So I changed the classes used in Redmine::Preparation to be idempotent. Please see the attached patch.

Now reloading works:

Reloading...
=> true

Best regards,
Thomas