How to serialize in nullable type ?

[lsaudon]

Hi,

I am migrating to null safety.

I have a JsonSerializer (moorRuntimeOptions.defaultSerializer = const JsonSerializer();).

I have this error type 'String' is not a subtype of type 'Date?' in type cast.

How to serialize in nullable type ?

IntColumn get birthDate => integer().map(const DateConverter()).nullable()();

import 'package:moor/moor.dart';

import '../../types/date.dart';

class DateConverter extends TypeConverter<Date, int> {
  const DateConverter();

  @override
  Date? mapToDart(int? fromDb) {
    if (fromDb == null) {
      return null;
    }
    return Date.fromDateTime(DateTime.fromMillisecondsSinceEpoch(fromDb));
  }

  @override
  int? mapToSql(Date? value) {
    return value?.millisecondsSinceEpoch;
  }

  static int today() => DateTime.now().toUtc().millisecondsSinceEpoch;
}

class JsonSerializer extends ValueSerializer {
  const JsonSerializer();

  @override
  T fromJson<T>(dynamic json) {
    if (T == DateTime) {
      return DateTime.parse(json as String) as T;
    }
    if (T == Date) {
      return Date.fromJson(json as String) as T;
    }
    return json as T;
  }

  @override
  dynamic toJson<T>(T value) {
    if (value is DateTime) {
      return value.toUtc().toIso8601String();
    }
    if (value is Date) {
      return value.toJson();
    }
    return value;
  }
}

[simolus3]

You could do something like this:

final listOfT = <T>[];
if (listOfT is List<DateTime?>) {
  return DateTime.parse(json as String) as T;
}
if (listOfT is List<Date?>) {
  return Date.fromJson(json as String) as T;
}

listOfT will be a List<Date?> if T is assignable to Date? which is probably what you want.

[lsaudon]

It works. Thank you very much.