How to gracefully perform a single sort in RoR ( AR )?

Question

Ruby on Rails

Evening in joy, seagulls in sweetness.
ENV: ruby ​​2.4.1 + ror 5.1.4 + postgresql
Model available:

create_table "phones", force: :cascade do |t|
    t.integer "id"
    t.string "type"
    t.datetime "created_at"
  end

The type field in the model can take only 3 values: ios, android, wp.
There are (for example) 12 records in the table - 4 of each type, created inconsistently (those. ios, ios, android, wp ... )
It is required to do sorting so that the ios type is displayed first, sorted by created_at, then android is the same by created_at, and wp for dessert.
You can actually solve it like this:

ordering_by_id = []
ordering_by_id << Phone.where(type: 'ios').order(created_at: :desc).select(:id) ....
ordering_by_id << Phone.where(type: 'android').order(created_at: :desc).select(:id) ....
@phones = Phone.where(id: ordering_by_id).order_as_specified(id: ordering_by_id)

But I think there is a more elegant way.
Thanks in advance and plus to you in karma!

Answer 1

Store the type like a rails enum. The field in base will be integer. Specify the desired order in the model.

Answer 2

Theoretically it should work like this

SELECT *
FROM phones
ORDER BY idx(array['ios','android','wp'], phones.type)

But this is not accurate :)
In general, here you need to look at how to do this at the base level, and not at the AR level