Flutter/Dart JSON and serialization of an existing library class

Question

I have a class:

import 'package:google_maps_flutter/google_maps_flutter.dart';

class Place {
  Place({
    this.address,
    this.coordinates,
  });

  final String address;
  final LatLng coordinates;
}

LatLng is a class of google_maps_flutter. How can I make my Place class serializable using json_annotation and json_serializable?

Thank you very much!

Solution

You can explicitly specify which methods of LatLng should be used for serialization using JsonKey annotation:

@JsonSerializable()
class Place {
  Place({
    this.address,
    this.coordinates,
  });

  final String address;
  @JsonKey(fromJson: LatLng.fromJson, toJson: jsonEncode)
  final LatLng coordinates;
}