Rails - Validate Nested Attributes Uniqueness with scope parent of parent

Question

I have a problem with the scoped uniqueness validation in Rails for nested attributes with a parent of parent.

Background

I have a rails 4 appl

Answer 1

I'll supply one possible solution. Not tested, but it should work, with a custom validation and an extra association.

In your Account model:

has_many :email_addresses, through: :contacts

In your EmailAddress model:

validate :uniqueness_of_mail

private
def uniqueness_of_mail
    account = contact.account
    if account.email_addresses.map(&:email).includes? email
        errors.add(email, 'Contact already has this email address')
        false
    else
        true
    end
end