Query for serialized fields

product_attribute.rb

class ProductAttribute < ActiveRecord::Base
  # ...

  serialize :value

  class << self
    def with_value(value)
      dumped_value = serialized_attributes['value'].dump(value)
      where(value: dumped_value)
    end

    def without_value(value)
      dumped_value = serialized_attributes['value'].dump(value)
      where('value != ?', dumped_value)
    end
  end
end