sharedlists/app/controllers/sessions_controller.rb

class SessionsController < ApplicationController

  skip_before_action :login_required!

  def new
  end

  def create
    user = User.find_by(email: params[:email])
    if user && user.authenticate(params[:password])
      session[:user_id] = user.id
      flash[:notice] = "Logged in!"
      redirect_to root_url
    else
      flash.now[:error] = "Invalid email or password"
      render :new
    end
  end

  def destroy
    session[:user_id] = nil
    redirect_to root_url, :notice => "Logged out!"
  end
end