DART How to map DATETIME into a SQFlite Database - flutter

Question

Overview:
App architecture details:
state management -> provider (not sure this is relevant, but in case you are interested)
data storage -> SQFlite
Specific issue details:
I have a calendarDay data model, with a property of
DateTime date;
I know that DateTime is not supported in SQLite (not in SQFlite either) and the recommendation is to use a String or Integer . I am struggling with how to actually do that.
Error I am getting:
flutter: *** WARNING ***
Invalid argument 2021-07-01 15:09:11.129598 with type DateTime.
Only num, String and Uint8List are supported. See https://github.com/tekartik/sqflite/blob/master/sqflite/doc/supported_types.md for details
This will throw an exception in the future. For now it is displayed once per type.
This is my setup:
calendar_day.dart
class CalendarDay {
int? id;
DateTime date;
CalendarDay(
{this.id,
required this.date});
// encode to SQLite database
Map<String, dynamic> toMap() {
final map = Map<String, dynamic>();
map['id'] = id;
map['date'] = date.toIso8601String(); //toString(); this toString did not work //jsonEncode(date) -> SERIALIZE THE ARRAYS INTO JSON strings, this did not work
return map;
}
// decode from SQLite database
static fromMap(Map map) {
return CalendarDay(
id: map['id'],
date: DateTime.parse(map['date']), // jsonDecode(map['date']));
}
}
database_client.dart
class DatabaseClient {
Future<Database> initializedDatabase() async {
WidgetsFlutterBinding.ensureInitialized();
String path = await getDatabasesPath();
return openDatabase(
join(path, 'three_things_database.db'),
onCreate: (database, version) async {
await database.execute(
"CREATE TABLE ${Strings.calendarDayDataBase} (id INTEGER PRIMARY KEY, date TEXT)",
); },
version: 1, ); }
// Create / insert calendarDay
Future<void> insertCalendarDay(CalendarDay day) async {
final Database database = await initializedDatabase();
await database.insert(
Strings.calendarDayDataBase,
day.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace,
);
}
}
I am thinking the problem lies with the toMap() method, since the error notes the DateTime object. But I am a bit stuck and don't really know how to get around this. Any help is greatly appreciated.
Additional things I have tried in toMap() :
I did include the code commented out, but for clarity, I'll post here:
I tried mapping the DateTime object to a JSONString. This would hopefully be enough for storing the map in SQLite database, but this approach threw the same error.
Tried mapping to a regular String using date.toString(). This did not work either. Since the recommendation (link above) from the SQFlite folks is to use ISO8601 string, I thought this approach would work.
Related question(s), yet did not solve my question:
Create DateTime column in SQFlite

Answer 1

Here's a clear example :
var dt = DateTime.now();
// String
var dtStr = dt.toIso8601String();
dt = DateTime.tryParse(dtStr);
// Int
var dtInt = dt.millisecondsSinceEpoch;
dt = DateTime.fromMillisecondsSinceEpoch(dtInt);