JsonSerializable: generate valid lists in strong mode

[johnpryan]

Currently, lists will generate a constructor like this:

// source
class User extends Object with _$UserSerializerMixin {
  List<int> tags;
  User(this.tags);
  factory User.fromJson(Map json) => _$UserFromJson(json);
}

// generated
User _$UserFromJson(Map json) => new User(
(json['tags'] as List)?.map((v0) => v0)?.toList());

Which generates the following strong-mode error:

WARNING: Unsafe implicit cast from 'List<dynamic>' to 'List<int>'. This usually indicates that type information was lost and resulted in 'dynamic' and/or a place that will have a failure at runtime. ([revolution] lib/model.g.dart:725)

[kevmoo]

Good catch! Pull requests welcome!

[kevmoo]

This is the spot -

source_gen/lib/generators/json_serializable_generator.dart

Line 235 in ff9de15

var output = "($varExpression as List)?.map(($itemVal) =>"

Just need to find a clean way to determine that the incoming value is what we want to store – and to reflect the target type.

[johnpryan]

awesome - thanks @a14n !