Saving data with the hive package - flutter

Question

How can I save and retrieve this map using hive?:
Map<DateTime, List<PressureModel>> pressures = {
DateTime(2023, 1, 11): [
PressureModel(
pressure: '144 / 64 - 74', date: DateTime(2023, 1, 11, 8, 45)),
PressureModel(
pressure: '157 / 64 - 77', date: DateTime(2023, 1, 11, 20, 8)),
],
DateTime(2023, 1, 12): [
PressureModel(
pressure: '146 / 71 - 92', date: DateTime(2023, 1, 12, 7, 46))
],
DateTime(2023, 1, 14): [
PressureModel(
pressure: '132 / 68 - 74', date: DateTime(2023, 1, 14, 10, 45)),
PressureModel(
pressure: '141 / 53 - 83', date: DateTime(2023, 1, 14, 21, 14)),
],
DateTime(2023, 1, 15): [
PressureModel(
pressure: '124 / 52 - 62', date: DateTime(2023, 1, 15, 10, 26)),
PressureModel(
pressure: '134 / 62 - 91', date: DateTime(2023, 1, 15, 18, 57)),
PressureModel(
pressure: '153 / 68 - 85', date: DateTime(2023, 1, 15, 21, 18)),
]};
This is what the PressureModel class looks like:
class PressureModel {
String pressure;
String action;
DateTime date;
PressureModel({required this.pressure, this.action = '', required this.date});
}
In case anyone is wondering, I did it through SharedPreferences, and ChatGTP helped me do it:
Here is the code to save the data:
Future<void> savePressures(
Map<DateTime, List<PressureModel>> pressures) async {
final prefs = await SharedPreferences.getInstance();
final encodedPressures = json.encode(
pressures.map((key, value) => MapEntry(key.toIso8601String(), value)));
await prefs.setString('pressures', encodedPressures);
}
Here is the code to get the data:
Future<Map<DateTime, List<PressureModel>>> loadPressures() async {
final prefs = await SharedPreferences.getInstance();
final encodedPressures = prefs.getString('pressures_list');
if (encodedPressures == null) {
return {};
}
final decodedPressures =
json.decode(encodedPressures) as Map<String, dynamic>;
final pressures = <DateTime, List<PressureModel>>{};
decodedPressures.forEach((key, value) {
pressures[DateTime.parse(key)] = (value as List<dynamic>)
.map((e) => PressureModel.fromJson(e))
.toList();
});
return pressures;
}

Answer 1

I think you can do that
for retrieve your data:
import 'package:hive/hive.dart';
Box<PressureModel> pressureBox = await Hive.openBox<PressureModel>('pressure');
Map<DateTime, List<PressureModel>> pressures = {};
for (var pressure in pressureBox.values) {
DateTime date = pressure.date;
if (pressures.containsKey(date)) {
pressures[date].add(pressure);
} else {
pressures[date] = [pressure];
}
}
for save your data:
List<PressureModel> pressureList = [];
for (var pressuresForDate in pressures.values) {
pressureList.addAll(pressuresForDate);
}
Box<PressureModel> pressureBox = await Hive.openBox<PressureModel>('pressure');
pressureBox.addAll(pressureList);