404 未找到記錄時

從記錄未找到錯誤中搶救而不是顯示異常或白頁：

class ApplicationController < ActionController::Base
  
  # ... your other stuff here 

  rescue_from ActiveRecord::RecordNotFound do |exception|
    redirect_to root_path, 404, alert: 'Record not found'
  end
end