How to stay DRY using private methods?

Question

I'm on Rails 5.0. Creating new controllers and adding more and more code there I've discovered that I have quite a lot of identical methods in private sections of each class like

private

def find_post
  @post = Posts.find(params[:id])
end

def find_user
  @user = User.find(params[:id])
end

def find_group
  ...
end

and so on.

Is there any way to include a "standard" set of private methods to all the classes that need it?

Answer 1

You can use concerns in controllers just like you can in models.

Just define a concern called Finders or something in app/controllers/concerns/finders.rb and then include Finders to use it.

Also note that since Ruby 2.0 def actually returns a symbol with the method name, so it is possible to do something like the following:

private def find_post
  @post = Posts.find(params[:id])
end

private def find_user
  @user = User.find(params[:id])
end

While it's true that this leads to slightly more typing, it's more explicit and much less error prone than the class level access modifiers.