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

I had the same problem with building objects from JSON. In JSON values are strings, but I wanted enum to validate if the value is correct. I wrote this helper which works with any enum, not a specified one:

class _EnumHelper {


 var cache = {};

  dynamic str2enum(e, s) {
    var o = {};
    if (!cache.containsKey(e)){
      for (dynamic i in e) {
        o[i.toString().split(".").last] = i;
      }
      cache[e] = o;
    } else {
      o = cache[e];
    }
    return o[s];
  }
}

_EnumHelper enumHelper = _EnumHelper();

Usage:

enumHelper.str2enum(Category.values, json['category']);

PS. I did not use types on purpose here. enum is not type in Dart and treating it as one makes things complicated. Class is used solely for caching purposes.