Fix issue with nested generics and genericArgumentFactories: true

Fixes #1047

Author: kevmoo

json_serializable/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 6.1.2
+
+- Fix issue with nested generics and `genericArgumentFactories: true`.
+  ([#1047](https://github.com/google/json_serializable.dart/issues/1047))
+
 ## 6.1.1
 
 - Fix `JsonKey.readValue` support to allow static functions.

json_serializable/lib/src/utils.dart

@@ -205,6 +205,10 @@ String typeToCode(
       (type.isNullableType || forceNullable) ? '?' : '',
     ].join();
   }
+
+  if (type is TypeParameterType) {
+    return type.getDisplayString(withNullability: false);
+  }
   throw UnimplementedError('(${type.runtimeType}) $type');
 }
 

json_serializable/pubspec.yaml

@@ -1,5 +1,5 @@
 name: json_serializable
-version: 6.1.1
+version: 6.1.2
 description: >-
   Automatically generate code for converting to and from JSON by annotating
   Dart classes.

json_serializable/test/generic_files/generic_class.dart

@@ -143,3 +143,35 @@ class Issue980ParentClass {
   @override
   int get hashCode => const DeepCollectionEquality().hash(list);
 }
+
+@JsonSerializable(genericArgumentFactories: true)
+class Issue1047ParentClass<T> {
+  Issue1047ParentClass({required this.edges});
+
+  factory Issue1047ParentClass.fromJson(
+          Map<String, dynamic> json, T Function(Object? json) fromJsonT) =>
+      _$Issue1047ParentClassFromJson<T>(json, fromJsonT);
+
+  final List<Issue1047Class<T>> edges;
+
+  Map<String, dynamic> toJson(Object? Function(T value) toJsonT) =>
+      _$Issue1047ParentClassToJson(this, toJsonT);
+}
+
+@JsonSerializable(genericArgumentFactories: true)
+class Issue1047Class<T> {
+  Issue1047Class({
+    required this.node,
+  });
+
+  factory Issue1047Class.fromJson(
+    Map<String, dynamic> json,
+    T Function(Object? json) fromJsonT,
+  ) =>
+      _$Issue1047ClassFromJson<T>(json, fromJsonT);
+
+  final T node;
+
+  Map<String, dynamic> toJson(Object? Function(T value) toJsonT) =>
+      _$Issue1047ClassToJson(this, toJsonT);
+}

json_serializable/test/generic_files/generic_class.g.dart

@@ -326,4 +326,33 @@ void main() {
       (json) => Issue980ParentClass.fromJson(json),
     );
   });
+
+  test('issue 1047 regression', () {
+    _roundTrip(
+      sourceJson: {
+        'edges': [
+          {'node': '42'}
+        ]
+      },
+      genericEncode: (o) => o.toString(),
+      genericDecode: (o) => int.parse(o as String),
+    );
+  });
+}
+
+void _roundTrip<T>({
+  required Map<String, dynamic> sourceJson,
+  required Object? Function(T) genericEncode,
+  required T Function(Object?) genericDecode,
+}) {
+  final json = jsonEncode(sourceJson);
+
+  final instance2 = Issue1047ParentClass<T>.fromJson(
+    jsonDecode(json) as Map<String, dynamic>,
+    genericDecode,
+  );
+
+  final json2 = jsonEncode(instance2.toJson(genericEncode));
+
+  expect(json2, json);
 }