Question

My User model is pretty standard – it has an email:string column and I validate the uniqueness of this in the User model with validates :email, :unique => true.

In order to allow alternate email addresses for users, I created a new model:

AlternateAddress, with columns user_id:integer and email:string.

A User has_many AlternateAddresses, and an AlternateAddress belongs to a User.
This setup makes for a simple nested form, like this: http://railscasts.com/episodes/196-nested-model-form-part-1.

I realized that I need to validate the 2 email:string columns (one in User.rb, the other in AlternateAddress.rb) “together” – so there are no duplicate email addresses anywhere.

How would I do this? Or, is my entire methodology off?

Thanks in advance.

Answer 1

You can add a custom validator so that it checks the user table and then the alternate addresses table:

class User < ActiveRecord::Base
  validate :email_uniqueness # custom
  validates :email, :uniqueness => true

  def email_uniqueness
    if AlternateAddress.find_by_email(self.email)
      self.errors.add(:email, "is already in use by another account")
    end
  end
end

You can add something similar to the AlternateAddress field. The method is a custom validator to take care of alternate addresses, but you still want the normal rails validator for uniqueness amongst users.