Shameless writing

write_rate.rb

# All index fields are required,
# the rest is the schemaless content
rate = Rate.put(hotel_id: 1,
  room_type: '1 bed',
  check_in_date: Date.today,
  discount_type: 'geo',
  net_price: 120.0) # potentially ~20 fields

rate[:hotel_id] # => 1
rate[:net_price] # => 120.0
rate.ref_key # => 0 # that's the version

rate[:net_price] = 130.0
rate.save
rate.ref_key # => 1

# Or:
rate.update(net_price: 140.0)
rate.ref_key # => 2