src/main/java/com/moral/service/impl/HistoryServiceImpl.java
@@ -406,7 +406,7 @@ String timeUnits = startTime.substring(0, 10).replace("-", ""); Map<String, Object> map = historyMapper.getAVGValueByMacAndTimeslot(mac, startTime, endTime, timeUnits); Map<String, Object> returnMap = new HashMap<>(); if (map.isEmpty()) { if (ObjectUtils.isEmpty(map) || map.isEmpty()) { returnMap.put("AQI", "N/V"); } else { Map<String, Double> AQIMap = new HashMap<>();