today_ai_weather/app/controllers/cities_controller.rb

class CitiesController < ApplicationController
  def index
    @regions = Region.includes(:countries).order(:name)
    @cities = City.includes(:country, country: :region).active.order(:name)

    if params[:region]
      @current_region = Region.friendly.find(params[:region])
      @cities = @cities.by_region(@current_region.id)
    end

    if params[:country]
      @current_country = Country.friendly.find(params[:country])
      @cities = @cities.by_country(@current_country.id)
    end

    @cities = @cities.page(params[:page]).per(10)
  end

  def show
    @city = City.friendly.find(params[:id])
  end
end