6. Custom Converters

Dog provides a number of built-in converters for common types. However, you may need to create your own converters for custom types. This section will explain how to create custom converters and how to register them in the DogEngine.

Example using the SimpleDogConverter

class LatLng {
  final double lat;
  final double lng;

  LatLng(this.lat, this.lng);

  @override
  String toString() => "LatLng($lat, $lng)";
}

@linkSerializer/*(1)!*/
class LatLngConverter extends SimpleDogConverter<LatLng>/*(2)!*/ {
  LatLngConverter() : super(serialName: "LatLng");

  @override
  LatLng deserialize(value, DogEngine engine) {
    var list = value as List;
    return LatLng(list[0], list[1]);
  }

  @override
  serialize(LatLng value, DogEngine engine) {
    return [value.lat, value.lng];
  }
}

1. The @linkSerializer annotation is used to automatically register the converter in the DogEngine.
2. The SimpleDogConverter class is a convenience class that implements DogConverter and provides both the NativeSerializerMode and the GraphSerializerMode. It also creates a synthetic structure for the converter type that uses the serialName.

In this example, we created a converter for the LatLng class. The converter is registered in the DogEngine using the @linkSerializer annotation. The 'SimpleDogConverter' base class is the easiest way to create a converter. It implements the DogConverter interface and provides both the NativeSerializerMode and the GraphSerializerMode. It also creates a synthetic structure for the converter type that uses the serialName.

Manual Registration

To manually register a converter in the DogEngine, you can use the registerAutomatic method to register converter and also link both the structure and it's associated type.

To only register the converter for a specific type, use registerAssociatedConverter.
To only register a structure, use registerStructure.
To only register a converter, without associating it with a type, use registerShelvedConverter.

Collections and generic types

For custom collections and generic types, you need to create a TreeBaseConverterFactory. This is relatively easy, refer to Tree Converters for more information.