searching belongs_to association via friendly_id slug

Question

An appointment belongs to a schedule. Without using friendly_id, the following code works, as expected, to build a list of appointments:

def show
    @appointments = Appointment.where(schedule_id: params[:id])
end

However, when I send the slug instead of the ID, things get more complicated. Something like Appointment.where(schedule.slug = "MYSLUG") is what I would love to do, but I ended up with this piece o' ugliness:

def show
    @appointments = Appointment.where(schedule_id: Schedule.where(slug: params[:id]))
end

It works, but it seems like I'm making it too complicated.

Suggestions to improve this code gratefully accepted.

Answer 1

I'd go with a pair of scopes. This helps keep your code readable and reusable (you get to use the same Schedule.for_slug method while searching for Schedules and Appointments).

# class Schedule
def self.for_slug(slug)
  where(slug: slug)
end

# class Appointment
def self.for_schedule_slug(slug)
  joins(:schedule).
    merge(Schedule.for_slug(slug))
end

Put them together like this

appointments = Appointment.for_schedule_slug(params[:id])