class FooController
  def index
    # The controller is responsible for gathering the things needed
    # to make the response. This should be a single line of code
    @things = Foo.things 
    
    # The controller is responsible for sending the view back to the user.
    # the view uses our instance variable above to render @things
    render :some_view
  end
end

# in an ideal controller those are the only two things that the action does
# 1. gathers the data
# 2. renders the view
#
# ideally each of these things is 1 line of code, but it might end up being
# more to deal with validation errors etc