easy-going-rails/app/controllers/strong_controller.rb

class StrongController < ApplicationController
  def index
    logger.info(Hot::Constants)
  end

  def update
    logger.info 'parameters', strong_params
    redirect_to strong_path, notice: 'form is ok'
  end

  private

  def strong_params
    # params.require(:strong).permit [:name, :surname, { birth: {} }] # implicit: any fields inside bith
    params.require(:strong).permit [:name, :surname, { birth: %i[date location] }] # explicit
  end
end