Enum from String

Question

I have an Enum and a function to create it from a String because i couldn\'t find a built in way to do it

Answer 1

enum in Dart just has too many limitations. The extension method could add methods to the instances, but not static methods.

I really wanted to be able to do something like MyType.parse(myString), so eventually resolved to use manually defined classes instead of enums. With some wiring, it is almost functionally equivalent to enum but could be modified more easily.

class OrderType {
  final String string;
  const OrderType._(this.string);

  static const delivery = OrderType._('delivery');
  static const pickup = OrderType._('pickup');

  static const values = [delivery, pickup];

  static OrderType parse(String value) {
    switch (value) {
      case 'delivery':
        return OrderType.delivery;
        break;
      case 'pickup':
        return OrderType.pickup;
        break;
      default:
        print('got error, invalid order type $value');
        return null;
    }
  }

  @override
  String toString() {
    return 'OrderType.$string';
  }
}

// parse from string
final OrderType type = OrderType.parse('delivery');
assert(type == OrderType.delivery);
assert(type.string == 'delivery');