Dart Built Value Deserialize List of Objects - dart

Question

I have an API that's returning a list of objects...
[{}, {}, {}, ...]
I already have a defined and working built_value model for each object. However, now I need to deserialize the list.
I currently am trying something like this:
List<Map<String, dynamic>> json = JSON.decode(DEMO_TASK);
json.expand<Task>((Map<String, dynamic> map) => _serializers.deserializeWith<Task>(Task.serializer, map));
However, that causes issues since it says _serializers.deserializeWith return type Task isn't an Iterable<Task> as defined by the closure.
How do I go about deserializing the list. I'm sure I'm missing something super basic.

Answer 1

In case you want to have more general approach you can use this code snippet:
In case anybody needs this functionality I leave here code snippet of how to handle this situation (code should be placed in serializers.dart file):
Serializers standardSerializers = (serializers.toBuilder()..addPlugin(StandardJsonPlugin())).build();
T deserialize<T>(dynamic value) =>
standardSerializers.deserializeWith<T>(standardSerializers.serializerForType(T), value);
BuiltList<T> deserializeListOf<T>(dynamic value) =>
BuiltList.from(value.map((value) => deserialize<T>(value)).toList(growable: false));
So if you have json file
[
{
"name": "test1",
"result": "success"
},
{
"name": "test2",
"result": "fail"
}
]
And built value class:
import 'package:built_value/built_value.dart';
import 'package:built_value/serializer.dart';
part 'test_class.g.dart';
abstract class TestClass implements Built<TestClass, TestClassBuilder> {
String get name;
String get result;
TestClass._();
factory TestClass([updates(TestClassBuilder b)]) = _$TestClass;
static Serializer<TestClass> get serializer => _$testClassSerializer;
}
You can use method deserializeListOf from above as:
import 'package:path_to_your_serializers_file/serializers.dart';
final BuiltList<TestClass> listOfTestClasses = deserializeListOf<TestClass>(json);

Answer 2

Yup. I missed something basic. I was thinking I was using a stream, but since it's a list you just have to use the .map function on a list.
List<Map<String, dynamic>> json = JSON.decode(DEMO_TASK);
List<Task> tasks = json.map<Task>((Map<String, dynamic> map) => _serializers.deserializeWith<Task>(Task.serializer, map)).toList();