Ruby on Rails how to convert ActiveRecord:Relation selection to hash?

Question

Ruby on Rails

Hello
Tell me how to convert such a selection to a hash where the key will be the external_key field, which is 100% unique.
Sample:

Customer.all
[#<Customer id: 1, name: "Рога", external_key: "00002256">,  #<Customer id: 1, name: "Копыта", external_key: "00002257">]

The hash you wanted to get?
{'00002256' => 1, '00002257' => 2}
I want to get a hash of such a plan in order to make it easier to search by the external_key field.

Answer 1

hash = {}
Customer.all.find_each { |c| hash[c.external_key] = c.id }

Answer 2

Customer.all.pluck(:external_key, :id).to_h