The most common case of this is having:

• a user model with an email
• a profile model with a username

I want a way to easily add an alternate login method (i.e. a profile's username)

similar to:

• User Info in separate table or removed #53
• Would it be useful to integrate login with username ? #127
• Username register login #128
• Implement login auth key according to Devise wiki #395
• I want to use a different column for provider instead of defalut "email" #485