ruby on rails 4 - How to query ActiveRecord with having and group -

i have simple appointment model storing start_time , user_id. i'd appointments starting in next 7 days in ascending order , grouped day. ideally result hash or multidimensional array such as

{   '30 march' =>       [appt1,appt12, appt3],   '31 march' =>      [appt5,appt2, appt7,appt8],   '1 april' =>       [appt10,appt11,appt9, appt6,appt4],   '2 april' =>      [appt15,appt21] } 

the query below gets desired results not in format want.

appointment.order(start_time: :asc).where("start_time <= ?", 7.days.from_now.end_of_day) 

is there way structure query or need format result separately?

one way group_by

appointments = appointment.order(start_time: :asc).   where("start_time <= ?", 7.days.from_now.end_of_day).   group_by { |a| a.start_time.to_date }