Help in validates_uniqueness_of helper

Hello. In my rails app, the user has to create an account. There are two
fields email and alt_email. The both should be unique. I used
validates_uniqueness_of helper to validate the fields. Now my problem is
the same user can create a fake account by interchanging the values of
email and alt_email fields. Please help in solving this issue. Thanks in

Not sure in what sense interchanging the values of
email and alt_email fields would create a fake account.

If you mean with the same two emails you can have two valid accounts
yes that is right. You have to decide if that is a problem.

If it is i guess it is also a problem to associate the same email to
two accounts, whatever the other address is

An obvious solution may be (with any number of alternative emails)
to have a separate Email table

class User
# (with any number of alternative emails)
has_many :emails

# with two emails
has_one :email
has_one :alt_email, :class => 'Email'

class Email
belongs_to :user
acts_as_list :scope => user_id
validates_uniqueness_of :address

Alternatively, if email and alt_email are just text columns in your
user table, just write a validation function
that checks uniqueness on the two columns (both compulsary).

validates_each :email, :alt_email do |record,attr,value|
   if value.blank?
     record.errors.add attr, "cannot be blank"
    email_taken = find(:conditions => ['( = ? OR
users.alt_email = ?) AND != ?', value, value,])
    record.errors.add attr, "(#{value}) is already taken" if

Hope this helps