Notify function and trigger

migration.rb

create_function(:notify, <<-SQL, language: :plpgsql, returns: :trigger, replace: true)
      BEGIN
        IF (TG_OP = 'DELETE') THEN
          PERFORM pg_notify(TG_TABLE_NAME, '{ \"id\": \"' || OLD.id || '\", \"event\": \"' || TG_OP || '\" }');
          RETURN OLD;
        ELSE
          PERFORM pg_notify(TG_TABLE_NAME, '{ \"id\": \"' || NEW.id || '\", \"event\": \"' || TG_OP || '\" }');
          RETURN NEW;
        END IF;
      END;
    SQL
  end
  
create_trigger :table, :notify, :notify, each_row: true