How to change default validation error messages on belongs_to field

Question

In Rails 5, belongs_to relation becomes required as default and gives Model must exist message on every failed validation. I want to localize default messages on every belongs_to occurrence at once. For example ...

In my model:

class Person < ApplicationRecord
  has_many :books
end

class Book < ApplicationRecord
  belongs_to :person
  validates :author_date, presence: true
end

In my localization file:

en:
     activerecord:
       errors:
         blank: "can't be blank" # not showing on book.errors[:person]

In console:

book = Book.new
book.save
puts book.errors.to_json
>> {person: ["must exist"], :author_date: ["can't be blank"]}

How can I localize must exist messages in YML file.

Answer 1

It has key required, try:

en:
  activerecord:
    errors:
      messages:
        required: "custom required message"