Hive Generic Enum Class Adapter Example

hive_enum_class_adapter_example.dart

import 'package:hive_flutter/hive_flutter.dart';

/**
 * Generic adapter for enum classes.
 */
class EnumClassAdapter<T extends Enum> extends TypeAdapter<T> {
  EnumClassAdapter(this.typeId, this.values);

  static const int _numberOfFields = 1;

  @override
  final int typeId;

  final List<T> values;

  @override
  T read(BinaryReader reader) {
    final numOfFields = reader.readByte();
    final fields = {for (var _ = 0; _ < numOfFields; _++) reader.readByte(): reader.read()};

    return values[fields[0] as int];
  }

  @override
  void write(BinaryWriter writer, T obj) {
    writer
      ..writeByte(_numberOfFields)
      ..writeByte(0)
      ..write(obj.index);
  }
}

//usage
enum Category { one, two, three }

Hive.registerAdapter<Category>(EnumClassAdapter<Category>(1, Category.values));
await Hive.initFlutter();