你的需求和这个差不多https://github.com/plataformatec/devise/wiki/How-To:-Allow-users-to-sign-in-using-their-username-or-email-address 其实就是重写 find_for_database_authentication

==> Configuration for any authentication mechanism # Configure which keys are used when authenticating a user. The default is # just :email. You can configure it to use [:username, :subdomain], so for # authenticating a user, both parameters are required.