【Rails】/users/:id ではなく/:username にする

理想

---

やり方

to_paramを使用する

user.rb

class User < ActiveRecord::Base
  validates_presence_of :username
  validates_uniqueness_of :username, case_sensitive: false

  def to_param
    username
  end

---

users_controller.rb

class UsersController < ApplicationController
  def show
    @user = User.find_by(username: params[:id])
  end
end

routes.rb

  resources: users, path: '/', only: [:show]