rails new my_app
cd my_app
Gemfile
gem 'friendly_id', '~> 5.1.0' # Note: You MUST use 5.0.0 or greater for Rails 4.0+
rails generate friendly_id
rails generate scaffold user name:string slug:string:uniq
rake db:migrate
edit app/models/user.rb
class User < ApplicationRecord
exten...
