Recursively removes key-value pairs from a Hash using lambda.

recursive_key_removal.rb

remove_id_attr = lambda do |obj|
  if obj.is_a?(Hash)
    obj.keys.each do |_k|
      if _k.to_s.eql?('_id')
        obj.delete(_k)
      elsif obj[_k].is_a?(Hash)
        remove_id_attr.call(obj[_k])
      elsif obj[_k].is_a?(Array)
        obj[_k].each{|o| remove_id_attr.call(o)}
      end
    end
  end
end

# remove _id attributes on sub-documents
remove_id_attr.call(demo_profile_doc)