module ReadActivity module Readable class << self attr_accessor :klasses def register_klass(klass) @klasses ||= [] @klasses << klass end end module ClassMethods def find_read_by(reader) self.joins(:read_activity_marks).merge(ReadActivityMark.where(reader: reader)) end def find_unread_by(reader) self.joins(%Q( LEFT OUTER JOIN (SELECT * FROM read_activity_marks WHERE reader_id = #{reader.id}) AS readable_marks ON readable_marks.readable_id = #{self.table_name}.id )).where("readable_marks.readable_id IS NULL") end end module InstanceMethods def read_by!(reader) ReadActivityMark.transaction do mark = self.read_activity_marks.build(reader: reader) mark.save! end end def read_by?(reader) mark = self.read_activity_marks.where(reader: reader) mark.exists? end def read_by_at(reader) mark = ReadActivityMark.find_by(readable: self, reader: reader) return mark.created_at if mark return nil end def readers Reader.klass.send(:find_who_read, self) end def unreaders Reader.klass.send(:find_who_unread, self) end end end end