Rails%203%20In%20Action

500 CHAPTER 17 Engines
17.7.2 A fake User model
Your engine has been deliberately designed to have no concept of authentication.
This is so it can be used with any application, independent of whatever authentication
system the application uses, be it Devise (which is what your main application uses) or
something else. In this section and the ones following, you’re going to be associating
topics and posts to users so that you know who’s been posting what. In order to this,
you’re going to need to generate a dummy User model.
When you have this model correctly set up, you’ll use it to restrict access to the new
topic and new post actions to only logged-in users, as well as using it to assign ownership
to posts and topics. You’ll be able to do this using the current_user made available
by the host application. It will be accessible in your engine’s controllers, as
Forem::ApplicationController inherits from ApplicationController.
To generate this new User model, you’re going to have to run the generator from
within the spec/dummy directory. This is so the generator will place the model code
within the dummy application and not your engine. You don’t need anything on this
User model besides a login field, which you’ll be using as the display value a little
later on by defining a to_s method inside this class. Within the spec/dummy directory,
run this command:
rails g model user login:string
To run the migration for this model, run rake db:migrate inside the spec/dummy
directory as well.
In this fake model, you’re going to need to define the to_s method your engine
will use to display the user’s name. Right now your users table only has a login field,
and so you’ll return that:
class User < ActiveRecord::Base
def to_s
login
end
end
With the fake model generated and the to_s method defined in it correctly, the only
thing left to do is to set up the initializer in your dummy application. Create a new file
at spec/dummy/config/initializers/forem.rb with this simple line:
Forem::Engine.user_class = User
That is all the preparation you need to do to notify your engine of this class. To make
your engine use this class, you’ll put this line in both the class definitions of app/
models/forem/post.rb and app/models/forem/topic.rb:
belongs_to :user, :class_name => Forem::Engine.user_class.to_s
This line will now reference the setting that’s configured by config/initializers/
forem.rb, thereby relating your posts and topics from your engine to the User class
within the application, forming a lovely bridge between the two.