addRow method
Implementation
Future<int?> addRow(WaterState? waterState) async {
waterState ??= waterLineDto.water_state;
int? nextTs;
try {
nextTs = (await waterLineDao.getLatestWaterLineDto(null)).water_ts;
} on SqlException {}
if (nextTs == null) nextTs = 0;
nextTs = nextTs + 1;
waterLineDto.water_ts = await waterLineDao.insertWaterLine(
waterLineDto.water_table_id, waterState, waterLineDto.water_error,
ts: nextTs);
return waterLineDto.water_ts;
}