This is the best serialization that I've been able to come up with after dealing with all kinds of gems and frustration

easy_serialization_example.rb

module EasySerialization
  extend ActiveSupport::Concern

  included do
    self.class_attribute :serialization_config
    self.serialization_config = Hash.new { |h, k| h[k] = [] }
  end

  def serializable_hash(opts={})
    opts ||= {}
    set = opts.fetch(:set, :default)
    set = :default unless self.serialization_config[set].present?

    result = {}
    self.serialization_config[set].each do |key|
      value = self.send(key)
      result[key] =
        if value.is_a?(ActiveRecord::Base)
          value.serializable_hash(opts)
        else
          value
        end
    end
    result
  end

  module ClassMethods
    def configure_for_serialization(*keys)
      set = :default
      if keys.last.respond_to?(:each_pair)
        set = keys.last.fetch(:set, :default)
        keys = keys[0..-2]
      end

      self.serialization_config[set].concat(keys)
    end
  end
end

### USAGE ###

class Foo < ActiveRecord::Base
  ...
  
  configure_for_serialization :id, :name, :url
  configure_for_serialization :id, :name, :contacts, set: :compact
  configure_for_serialization :id, :url, :whatever_else, set: :api

  ...
end