golang Flow流程添加element时间轴

type DocEventsHistory struct {
	FromState string
	DocAction string
	ToState   string
	Group     string
	Data      string
	Ctime     time.Time
}

// DocEventsHistory answers the possible document wf_docevent_application.
func (_DocEvents) DocEventsHistory(dtype DocTypeID, id DocumentID) ([]*DocEventsHistory, error) {
	q := `
	SELECT dsm1.name, dam.name, dsm2.name, gm.name, de.data, de.ctime
	FROM wf_docevent_application dea
	JOIN wf_docstates_master dsm1 ON dsm1.id = dea.from_state_id
	JOIN wf_docstates_master dsm2 ON dsm2.id = dea.to_state_id
	JOIN wf_docevents de ON de.id = dea.docevent_id
	JOIN wf_docactions_master dam ON dam.id = de.docaction_id
	JOIN wf_groups_master gm ON gm.id = de.group_id
	WHERE dea.doctype_id = ? AND dea.doc_id = ? ORDER BY de.ctime DESC
	`
	rows, err := db.Query(q, dtype, id)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	ary := make([]*DocEventsHistory, 0, 10)
	for rows.Next() {
		var elem DocEventsHistory
		err = rows.Scan(&elem.FromState, &elem.DocAction, &elem.ToState, &elem.Group, &elem.Data, &elem.Ctime)
		if err != nil {
			return nil, err
		}
		ary = append(ary, &elem)
	}
	if err = rows.Err(); err != nil {
		return nil, err
	}

	return ary, nil
}