How can I JSON.stringify a Collection in Dart

Question

How can I made a JSON string out of a collection in dart, as I can do it with Maps. The docs say I can pass a map or a an array into the JSON.stringify() method. But there are no Array data type in Dart and passing a collection gives me an exception.

I've a naive workaround, but I wonder if there will be a better way to do this:

    String s = '[';
    bool first=true;

    _set.forEach(function(item){
      if (first) {
        first = false;
      } else {
        s+=',';
      }
      s += JSON.stringify(item);
    });
    s +=']';
    print(s);
    return s;

Answer 1

In Dart, you can get a JSON String out of an Object using the JsonEncoder's convert method. Here is an example:

import 'dart:convert';

void main() {
  final jsonEncoder = JsonEncoder();

  final collection1 = List.from([1, 2, 3]);
  print(jsonEncoder.convert(collection1)); // prints [1,2,3]

  final collection2 = List.from(['foo', 'bar', 'dart']);
  print(jsonEncoder.convert(collection2)); // prints ["foo","bar","dart"]

  final object = {'a': 1, 'b': 2};
  print(jsonEncoder.convert(object)); // prints {"a":1,"b":2}
}

Answer 2

Passing a list works for me:

• in the Dart VM importing dart-sdk/lib/frog/server/dart_json.dart
• in Dartium importing json:dart

using this code:

void main() {
  var list = new List.from(["a","b","c"]);
  print(JSON.stringify(list));
}

prints this JSON snippet:

["a","b","c"]

Doesn't work for new Set.from(...) which is expected, given that JSON only deals in maps and lists.