def bytes
      return 0 if member_object_ids.empty?

      raise "Collection must be saved to query for bytes" if new_record?

      # One query per member_id because Solr is not a relational database
      member_object_ids.collect { |work_id| size_for_work(work_id) }.sum
    end
def bytes
      return 0 if member_object_ids.empty?

      raise "Collection must be saved to query for bytes" if new_record?

      # One query per member_id because Solr is not a relational database
      member_object_ids.collect { |work_id| size_for_work(work_id) }.sum
    end
Compute the sum of each file in the collection using Solr to
 avoid having to access Fedora

 @return [Fixnum] size of collection in bytes
 @raise [RuntimeError] unsaved record does not exist in solr