Devise login with membership id

I am currently working on another small project, where Devise is used for authentication. The project requires that users log in with a membership id instead of an email and a password (these are default Devise settings). The project is set up in such a way that an admin creates users using their membership id, and then the users log in with the membership id. The users can't delete their account; only an admin can.

Based on Devise documentation and other research, it appeared that several things needed to be done. First, one needs to create a membership id in the User table, and to add this parameter to the list of permitted parameters. Second, the log in form needs to be modified so that it includes the membership id only.

However, adding the membership id to the list of permitted parameters was only a partial solution. It would allow me to register the user using the membership id but when I would try to log the user in, I would get an authorization error.

Since Devise uses Warden for authorization and the default settings include email and password, the solution was to add another Warden strategy, so that the membership id would be recognized as a legitimate choice.

In initializers directory I created a file named membership_strategy.rb:

require 'devise/strategies/authenticatable'

module Devise
  module Strategies
   class Membershipid < Authenticatable

     def valid?
       true
     end

     def authenticate!
       if !params[:user].nil?
         auth_params = {}
         auth_params[:membershipid] = params[:user][:membershipid]
         resource = mapping.to.find_for_authentication(auth_params)

         if validate(resource){ resource.find_for_database_authentication(auth_params) }
            success!(resource)
         else
            fail!(:invalid)
         end
       end
     end
   end
  end
end
Warden::Strategies.add(:membershipid, Devise::Strategies::Membershipid) 

In initializers/devise.rb the following line needs to be appended to the beginning:

config.warden do |manager|
   manager.default_strategies(:scope => :user).unshift :membershipid
end