在 dart 中动态定义或转换变量类型

Question

So I have this func:

Future<void> syncedData(String dataType, Map<String, dynamic> data) async {
  // Open the Hive Box
  await _openBoxByName(dataType);

  // Put each data element in the Hive Box
  data.forEach((k, v) {
    Workout _v = v;
    // var _v = v as Workout; - kinda same result

    _putData(k, _v.toJson().toString(), dataType);
  });
}

I also have 3 Model Classes: Workout , Days and Years .

In order for me to get .toJson() method from v, I need to do: Workout _v = v; . But I do not know how can I cast the type of v dynamically from Workout , Days and Years Model Classes?

If I do not cast v explicit as Workout Class Model, dart doesn`t know about any of my WOrkouts methods.

I have tried something like this, but it did not work:

if  (dataType == 'workout')  Workout _v = v;
if  (dataType == 'days')  Days _v = v;
if  (dataType == 'years')  Years _v = v;

Thank you

Answer 1

You should probably encode this as a Map that has values for keys of workout, days, or years. I think that'll JSON quite nicely.