-- set generic with date and uid combined
-- don't use with set_generic/set_uid together

CREATE OR REPLACE FUNCTION set_generic()
RETURNS TRIGGER AS
$$
DECLARE
    random_length INT = 32; -- long for massive data
BEGIN
    IF TG_OP = 'INSERT' THEN
        NEW.date_created := 'now';
        IF NEW.uid IS NULL THEN
            NEW.uid := random_string(random_length);
        END IF;
    ELSIF TG_OP = 'UPDATE' THEN
        NEW.date_updated := 'now';
    END IF;
    RETURN NEW;
END;
$$
LANGUAGE 'plpgsql';