Custom Data Type converter

[ebelevics]

Problem

If the goal is to use realm model as app and local storage entity, then IMO it should be as close and flexible as dart data class models itself. So far the only way how to convert custom types to realm data type is by writing getter and setter. Not only it makes code less readable but also:

• have to duplicate same code in multiple RealmModels for Color property
• during object construction have to still pass colorAsInt

@RealmModel()
class $Car {
  late String name;

  @MapTo('color')
  late int colorAsInt;
  Color get color => Color(colorAsInt);
  set color(Color c) => colorAsInt = c.value;
}

Solution

https://pub.dev/packages/json_serializable provides good way of dealing with custom types.

@JsonSerializable()
class Sample4 {
  Sample4(this.value);

  factory Sample4.fromJson(Map<String, dynamic> json) =>
      _$Sample4FromJson(json);

  @EpochDateTimeConverter()
  final DateTime value;

  Map<String, dynamic> toJson() => _$Sample4ToJson(this);
}

class EpochDateTimeConverter implements JsonConverter<DateTime, int> {
  const EpochDateTimeConverter();

  @override
  DateTime fromJson(int json) => DateTime.fromMillisecondsSinceEpoch(json);

  @override
  int toJson(DateTime object) => object.millisecondsSinceEpoch;
}

It is using @EpochDateTimeConverter as custom data type converter, and then in Sample4 you can you desired DateTime type as value. In realm case it would look similar like this:

@RealmModel()
class $Car {
  late String name;

  @ColorConverter
  late Color color;
}

class ColorConverter implements RealmConverter<Color, int> {
  const ColorConverter();

  @override
  Color fromRealm(int val) => Color(val);

  @override
  int toRealm(Color object) => object.value;
}

And this would deal with stated problems above:

• I takes now only 2 lines of code instead of 4
• I can create object with Car("Ford", Colors.white)
• I can reuse same ColorConverter in other RealmModels

ColorConverter and other common data converter types could be predefined, but also it adds even possibility to convert data with bigger complexity and annotate only in 2 lines of code.

Maybe this or similar feature is in near future, but I couldn't find it anywhere.

Alternatives

No response

How important is this improvement for you?

I would like to have it but have a workaround

Feature would mainly be used with

Local Database only

[blagoev]

Thanks for the suggestion. We will consider adding in the future.

[dotjon0]

Plus 1

[dotjon0]

This would be a major improvement.

[derrickgw]

This would be great as it would also allow storage of enums, and could probably even be done without the user explicitly generating the converter.