code: public void updateFromFile(MultipartFile file) {
          ObjectMapper objectMapper = ValidationObjUtil.getDefaultObjectMapper();
  
          try {
              String jsonStr = new String(file.getBytes(), "UTF-8");
              List<ValidationData> list = objectMapper.readValue(jsonStr, objectMapper.getTypeFactory().constructCollectionType(List.class, ValidationData.class));
              List<ReqUrl> reqUrls = ValidationReqUrlUtil.getUrlListFromValidationDatas(list);
              reqUrls.forEach(reqUrl -> {
                  this.deleteValidationData(reqUrl);
              });
              Map<Long, Long> idsMap = new HashMap<>();
              List<ValidationData> saveList = new ArrayList<>();
  
              list.forEach(data -> {
                  long oldId = data.getId();
                  data.setId(null);
                  data = this.validationDataRepository.save(data);
                  idsMap.put(oldId, data.getId());
                  saveList.add(data);
              });
  
              saveList.forEach(data -> {
                  if (data.getParentId() != null) {
                      data.setParentId(idsMap.get(data.getParentId()));
                      this.validationDataRepository.save(data);
                  }
              });
  
          } catch (IOException e) {
              log.info("file io exception : " + e.getMessage());
          }
      }
docs: Update from file.
  
  @param file the file