Query records through its belongs_to relation in Rails

Question

I have an Activities model, and they belong_to a Location

How do i select all the activities whose location.country = Australia? (for example)

Can I do this

Answer 1

Yes, a scope can be used. Something like this ought to work on the Activities model:

scope :down_under, 
    joins(:locations).
    where("locations.country = 'Australia')