How to find a devise user by user_id?

So as im following along in this tutorial. I have made some changes because I have already taken a course prior to this and I wanted to challenge myself.However, I have come to a problem that has me scratching my head.

What I would like to do is get the user_id of a user's show page. What the tutorial has done is create a new field for devise, profile_name. (I understand the importance of this because we would not want duplicate routes for two different users)

I skipped this step, because i did not want my users to be identified that way. I wanted them to be identified by their user_id/ + first_name + last_name. In doing what the tutorial did, what he achieved was that he created custom routes for each individual user signed up to his site by the use of their unique profile_name. In my case it would be user_id/ + first_name + last_name. If someone could shed some light on this and hopefully also point me to a resource I could potentially learn more on this subject I would really appreciate it. What really appealed to me was the fact that you were able to create custom routes for each individual on your site. I did think of using

@user = User.find(current_user) but that didnt work so well. It shows on the page but did not create custom routes like i thought it would. For instance in my case it would be http://localhost:3000/105/edwardlim.

Thanks for reading and have a nice day! :D

This is what you guys had in the tutorial.

class ProfileController < ApplicationController
    before_filter :authenticate_user!, only: [:show]

  def show
    @user = User.find_by_profile_name(params[:id])
    //@user = User.find_by_user_id(params[:id]) //my code that I thought would work
    if @user
        @statuses = @user.statuses.all
        render action: :show
    else
        render file: 'public/404', status: 404, formats: [:html]
    end
  end
end

ROUTES FILE

Rails.application.routes.draw do
  get '/:id', to: 'profile#show'