Ruby on rails user role always remains nil using enum - ruby-on-rails

Question

I am trying to add multiple user role functionality in devise. I am using enum for different roles, but somehow user role always remains nil after a new user signs up.
here is my implementation
user model
class User < ApplicationRecord
rolify
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
enum role: { student: 0, assistant: 1, teacher: 2}
end
I also added role in strong params of registration controller
registration_controller
class RegistrationsController < Devise::RegistrationsController
private
def sign_up_params
params.require(:user).permit(:username, :email, :password, :password_confirmation, keys: [:role])
end
def account_update_params
params.require(:user).permit(:username, :email, :password, :password_confirmation, :current_password, keys: [:role])
end
end
view
<%= f.select :role, User.roles %>
What I want is that role of new user should be whatever he/she selects from dropdown while registering
But its role is always set to nil after registering. Can someone please explain how to fix this
I have read many answers and added key: [:role] in strong params but still its not working
Thanks

Answer 1

If you intend on using Rolify you should remove that enum column.
class User < ApplicationRecord
rolify
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
end
Rolify uses two tables (roles and users_roles) to store the roles of a user. This allows a user to have many roles while a role can have many users.
While you can create your own primitive role system based on an enum column having both in tandem will certainly confusion as Rolify's methods such as .has_role? will not take your enum column into account.
If you want to let users select roles with rolify you would do:
<%= f.collection_select :role_ids,
Role.where(name: ['student', 'assistant', 'teacher']), :id, :name %>
class RegistrationsController < Devise::RegistrationsController
private
def sign_up_params
params.require(:user).permit(:username, :email, :password, :password_confirmation, role_ids: [])
end
def account_update_params
params.require(:user).permit(:username, :email, :password, :password_confirmation, :current_password, role_ids: [])
end
end