type 'int' is not a subtype of type 'String' in type cast

[jackselvam]

build_runner generating json['id'] as String code which is not working in latest dart.

i am getting "type 'int' is not a subtype of type 'String' in type cast" error.
if i change "json['id'] as String" to json['id'].toString(), it's working.

please fix the issue.

[kevmoo]

Please include your source Dart class and the generated output

[jackselvam]

@JsonSerializable()
class LookupModel {
  final BigInt id;
  final String value;
  LookupModel(this.id,this.value);
  
  factory LookupModel.fromJson(Map<String, dynamic> json) =>
      _$LookupModelFromJson(json);
  Map<String, dynamic> toJson() => _$LookupModelToJson(this);
}

into

LookupModel _$LookupModelFromJson(Map<String, dynamic> json) {
  return LookupModel(
      json['id'] == null ? null : BigInt.parse(json['id'] as String),
      json['value'] as String);
}

Map<String, dynamic> _$LookupModelToJson(LookupModel instance) =>
    <String, dynamic>{'id': instance.id?.toString(), 'value': instance.value};

[kevmoo]

BigInt is too big for int ... so if you're bringing in JSON values with {'int': 42} that won't work – unless you use a custom converter.

[jackselvam]

latest dart version doesn't supporting "json['id'] as String".
Same i was using two months before, it was working

[JonasABR]

i'm having the same issue. Does the custom converter work @jackselvam ?

[kevmoo]

The code I've implemented here assumes the source value is a STRING "42" not a number 42. This is to ensure we round-trip all valid BigInt values – which go well beyond what int supports.

It sounds like you'd like to support decoding JSON numbers here, too?

[srvstvnhl]

If i use the toString() it is not working. and if i use the as String, then it is throwing the error that is mentioned in the issue thread.

[kevmoo]

What's the JSON you're trying to parse?

[exeptionerror]

[Solved] type ‘int’ is not a subtype of type ‘String’ error in Dart

[gb4dev]

Hello, is there anything new about this problem ?

[gb4dev]

Hello, is there anything new about this problem ?

So i finally use double instead of BigInt for unsigned int 64

[kevmoo]

You can also create a custom converter to handle this case: https://pub.dev/packages/json_serializable#custom-types-and-custom-encoding