how to use either email or login in Authlogic

I'm using Authlogic with my Ruby on Rails App. I would like user to enter either user name or password in one field to authenticate. How do I do this with Authlogic?

I know I can switch to usin开发者_如何学运维g email:

  acts_as_authentic do |c|
    c.login_field = :email
  end

I was sure if I can tell Authlogic to use either.

Cheers,

Tam

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Check this.