Using an int as a Map key

[SylvainLosey]

I would like to create Maps of Objects with their Id as key, but I get this error message from json_serializable:

Could not generate `fromJson` code for `pickups` because of type `int`. Map keys must be of type `String`, enum, `Object` or `dynamic`.

Is there any reason for this ?

[kevmoo]

I would like to create Maps of Objects with their Id as key, but I get this error message from json_serializable:

Could not generate `fromJson` code for `pickups` because of type `int`. Map keys must be of type `String`, enum, `Object` or `dynamic`.

Is there any reason for this ?

Yup. JSON requires keys to be String. We'd have to add logic to convert to/from ints to String.

Rolling this into #396

[fzyzcjy]

Seems that now it is implemented! YEAH!

enum MyEnum { apple, banana, orange }

@JsonSerializable()
class HelloEntity {
  List<String>? list;
  Map<int, int>? intIntMap;
  Map<int, Object>? intObjMap;
  Map<MyEnum, HelloEntity>? enumRecursiveMap;
  Map<int, MyEnum>? intEnumMap;

  HelloEntity();

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

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

HelloEntity _$HelloEntityFromJson(Map<String, dynamic> json) {
  return HelloEntity()
    ..list = (json['list'] as List<dynamic>?)?.map((e) => e as String).toList()
    ..intIntMap = (json['intIntMap'] as Map<String, dynamic>?)?.map(
      (k, e) => MapEntry(int.parse(k), e as int),
    )
    ..intObjMap = (json['intObjMap'] as Map<String, dynamic>?)?.map(
      (k, e) => MapEntry(int.parse(k), e as Object),
    )
    ..enumRecursiveMap =
        (json['enumRecursiveMap'] as Map<String, dynamic>?)?.map(
      (k, e) => MapEntry(_$enumDecode(_$MyEnumEnumMap, k),
          HelloEntity.fromJson(e as Map<String, dynamic>)),
    )
    ..intEnumMap = (json['intEnumMap'] as Map<String, dynamic>?)?.map(
      (k, e) => MapEntry(int.parse(k), _$enumDecode(_$MyEnumEnumMap, e)),
    );
}

Map<String, dynamic> _$HelloEntityToJson(HelloEntity instance) =>
    <String, dynamic>{
      'list': instance.list,
      'intIntMap': instance.intIntMap?.map((k, e) => MapEntry(k.toString(), e)),
      'intObjMap': instance.intObjMap?.map((k, e) => MapEntry(k.toString(), e)),
      'enumRecursiveMap': instance.enumRecursiveMap
          ?.map((k, e) => MapEntry(_$MyEnumEnumMap[k], e)),
      'intEnumMap': instance.intEnumMap
          ?.map((k, e) => MapEntry(k.toString(), _$MyEnumEnumMap[e])),
    };

K _$enumDecode<K, V>(
  Map<K, V> enumValues,
  Object? source, {
  K? unknownValue,
}) {
  if (source == null) {
    throw ArgumentError(
      'A value must be provided. Supported values: '
      '${enumValues.values.join(', ')}',
    );
  }

  return enumValues.entries.singleWhere(
    (e) => e.value == source,
    orElse: () {
      if (unknownValue == null) {
        throw ArgumentError(
          '`$source` is not one of the supported values: '
          '${enumValues.values.join(', ')}',
        );
      }
      return MapEntry(unknownValue, enumValues.values.first);
    },
  ).key;
}

P.S. seems to only support the following

Map keys must be one of: Object, dynamic, enum, String, BigInt, DateTime, int, Uri.