It has to be something like this
class Settings
settings column: 'config' do
key :users do
key :mails_for_errors do
validates_presence
before_save do |value|
value.split(/\s*,\s*/)
end
default ['a@mail.es']
end
key :mails_for_warinings, type: :array, default: User.first.email
key :max_logins do
validates_length in: 10..20
default 6
end
end
end
end