The situation: You use Devise, and want to make emails optional because you login via username and why bother with emails?

Or maybe you want to be able to re-use email addresses as logins, say across subdomains. Or even multiple email addresses?

Your problem: Devise validatable hates on this and laughs are your attempts.

Keep the sweet Devise format validations, and customize devise validations by rolling your own

First, remove the :validatable argument from the devise method

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devise :database_authenticatable, :token_authenticatable 

Then, you’ll need to implement your own validations. Depending on your intentions, either include or exclude validates_presence_of :email

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  validates_uniqueness_of    :email,     :case_sensitive => false, :allow_blank => true, :if => :email_changed?
  validates_format_of :email, :with  => Devise.email_regexp, :allow_blank => true, :if => :email_changed?
  validates_presence_of   :password, :on=>:create
  validates_confirmation_of   :password, :on=>:create
  validates_length_of :password, :within => Devise.password_length, :allow_blank => true

I know the above looks vaguely familiar… say: what you used to write all the time before Devise kicked in. But look at the devise validatable source – this is all it’s doing anyway.

To allow email re-use across accounts, add :scope=>:accont_id on the uniqueness validation.

Also cool: use the Devise.email_regexp and Devise.password_length to get good email validations.

Version Disclosure: This post was valid with Devise 1.4.6 and Rails 2.3/3.0/3.1.