Change Login [Gem Devise Ruby On Rails]

Create a migration to add the username:

$ rails generate migration add_username_to_users username:string

Run a migration:

$ rake db:migrate

Change the file /config/initializers/devise.rb by exchanging: email by: username

config.authentication_keys = [ :username ]

Finally, change your view:

<li><%= f.label :username %> <%= f.text_field :username %></li>

Reference: railscasts

I have not yet had to do this, but there is this devise wiki that demonstrates how to use username (or code) to log in.

link