Add support for enums

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.2
+
+* Enable support for `enum` values.
+
 ## 0.2.1
 
 * Upgrade to `package:source_gen` v0.7.0

lib/src/json_serializable_generator.dart

@@ -13,6 +13,7 @@ import 'package:source_gen/source_gen.dart';
 import 'json_serializable.dart';
 import 'type_helper.dart';
 import 'type_helpers/date_time_helper.dart';
+import 'type_helpers/enum_helper.dart';
 import 'type_helpers/iterable_helper.dart';
 import 'type_helpers/json_helper.dart';
 import 'type_helpers/map_helper.dart';
@@ -24,6 +25,7 @@ class JsonSerializableGenerator
   static const _coreHelpers = const [
     const IterableHelper(),
     const MapHelper(),
+    const EnumHelper(),
     const ValueHelper()
   ];
 

lib/src/type_helpers/date_time_helper.dart

@@ -1,6 +1,7 @@
 import 'package:analyzer/dart/element/type.dart';
 import 'package:source_gen/source_gen.dart' show TypeChecker;
 import '../type_helper.dart';
+import 'type_helper_utils.dart';
 
 class DateTimeHelper extends TypeHelper {
   const DateTimeHelper();
@@ -28,14 +29,8 @@ class DateTimeHelper extends TypeHelper {
       return null;
     }
 
-    var buffer = new StringBuffer();
-
-    if (nullable) {
-      buffer.write("$expression == null ? null : ");
-    }
-
-    buffer.write("DateTime.parse($expression as String)");
-    return buffer.toString();
+    return commonNullPrefix(
+        nullable, expression, "DateTime.parse($expression as String)");
   }
 }
 

lib/src/type_helpers/enum_helper.dart

@@ -0,0 +1,31 @@
+import 'package:analyzer/dart/element/type.dart';
+import '../type_helper.dart';
+import 'type_helper_utils.dart';
+
+class EnumHelper extends TypeHelper {
+  const EnumHelper();
+
+  @override
+  String serialize(DartType targetType, String expression, bool nullable,
+      TypeHelperGenerator serializeNested) {
+    if (targetType is InterfaceType && targetType.element.isEnum) {
+      return commonNullPrefix(
+          nullable, expression, '$expression.toString().split(".")[1]');
+    }
+
+    return null;
+  }
+
+  @override
+  String deserialize(DartType targetType, String expression, bool nullable,
+      TypeHelperGenerator deserializeNested) {
+    if (targetType is InterfaceType && targetType.element.isEnum) {
+      return commonNullPrefix(
+          nullable,
+          expression,
+          '$targetType.values.singleWhere('
+          '(x) => x.toString() == "$targetType.\${$expression}")');
+    }
+    return null;
+  }
+}

lib/src/type_helpers/json_helper.dart

@@ -1,6 +1,7 @@
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import '../type_helper.dart';
+import 'type_helper_utils.dart';
 
 class JsonHelper extends TypeHelper {
   const JsonHelper();
@@ -43,11 +44,7 @@ class JsonHelper extends TypeHelper {
     // github.com/dart-lang/json_serializable/issues/19
     var result = "new ${targetType.name}.fromJson($expression$asCast)";
 
-    if (nullable) {
-      result = "$expression == null ? null : " + result;
-    }
-
-    return result;
+    return commonNullPrefix(nullable, expression, result);
   }
 }
 

lib/src/type_helpers/map_helper.dart

@@ -1,6 +1,7 @@
 import 'package:analyzer/dart/element/type.dart';
 import 'package:source_gen/source_gen.dart' show TypeChecker;
 import '../type_helper.dart';
+import 'type_helper_utils.dart';
 
 /// Name used for closure argument when generating calls to `map`.
 final _closureArg = "e";
@@ -41,11 +42,7 @@ class MapHelper extends TypeHelper {
           "$expression.keys,"
           "$expression.values.map(($_closureArg) => $subFieldValue))";
 
-      if (nullable) {
-        result = "$expression == null ? null :" + result;
-      }
-
-      return result;
+      return commonNullPrefix(nullable, expression, result);
     }
     throw new UnsupportedTypeError(targetType, expression);
   }
@@ -85,12 +82,7 @@ class MapHelper extends TypeHelper {
       // No mapping of the values is required!
 
       var result = "new Map<String, $valueArg>.from($expression as Map)";
-
-      if (nullable) {
-        result = "$expression == null ? null :" + result;
-      }
-
-      return result;
+      return commonNullPrefix(nullable, expression, result);
     }
 
     // In this case, we're going to create a new Map with matching reified
@@ -102,11 +94,7 @@ class MapHelper extends TypeHelper {
         "($expression as Map<String, dynamic>).keys,"
         "($expression as Map).values.map(($_closureArg) => $itemSubVal))";
 
-    if (nullable) {
-      result = "$expression == null ? null :" + result;
-    }
-
-    return result;
+    return commonNullPrefix(nullable, expression, result);
   }
 }
 

lib/src/type_helpers/type_helper_utils.dart

@@ -0,0 +1,5 @@
+String commonNullPrefix(
+        bool nullable, String expression, String unsafeExpression) =>
+    nullable
+        ? "$expression == null ? null : $unsafeExpression"
+        : unsafeExpression;

pubspec.yaml

@@ -1,5 +1,5 @@
 name: json_serializable
-version: 0.2.1
+version: 0.2.2-dev
 author: Dart Team <misc@dartlang.org>
 description: Generates utilities to aid in serializing to/from JSON.
 homepage: https://github.com/dart-lang/json_serializable

test/json_serializable_integration_test.dart

@@ -14,22 +14,22 @@ void main() {
     }
 
     test("null", () {
-      roundTripPerson(new Person(null, null));
+      roundTripPerson(new Person(null, null, null));
     });
 
     test("empty", () {
-      roundTripPerson(new Person('', '',
+      roundTripPerson(new Person('', '', null,
           middleName: '',
           dateOfBirth: new DateTime.fromMillisecondsSinceEpoch(0)));
     });
 
     test("now", () {
-      roundTripPerson(new Person('a', 'b',
+      roundTripPerson(new Person('a', 'b', House.gryffindor,
           middleName: 'c', dateOfBirth: new DateTime.now()));
     });
 
     test("now toUtc", () {
-      roundTripPerson(new Person('a', 'b',
+      roundTripPerson(new Person('a', 'b', House.hufflepuff,
           middleName: 'c', dateOfBirth: new DateTime.now().toUtc()));
     });
 
@@ -46,17 +46,17 @@ void main() {
     }
 
     test("null", () {
-      roundTripOrder(new Order());
+      roundTripOrder(new Order(Category.charmed));
     });
 
     test("empty", () {
-      roundTripOrder(new Order(const [])
+      roundTripOrder(new Order(Category.strange, const [])
         ..count = 0
         ..isRushed = false);
     });
 
     test("simple", () {
-      roundTripOrder(new Order(<Item>[
+      roundTripOrder(new Order(Category.top, <Item>[
         new Item(24)
           ..itemNumber = 42
           ..saleDates = [new DateTime.now()]
@@ -65,11 +65,20 @@ void main() {
         ..isRushed = true);
     });
 
-    test('empty json', () {
-      var order = new Order.fromJson({});
+    test('almost empty json', () {
+      var order = new Order.fromJson({'category': 'top'});
       expect(order.items, isEmpty);
+      expect(order.category, Category.top);
       roundTripOrder(order);
     });
+
+    test('required, but missing enum value fails', () {
+      expect(() => new Order.fromJson({}), throwsStateError);
+    });
+
+    test('mismatched enum value fails', () {
+      expect(() => new Order.fromJson({'category': 'weird'}), throwsStateError);
+    });
   });
 
   group('Item', () {

test/test_files/json_test_example.dart

@@ -12,12 +12,16 @@ import 'package:json_serializable/annotations.dart';
 
 part 'json_test_example.g.dart';
 
+enum House { gryffindor, hufflepuff, ravenclaw, slytherin }
+
 @JsonSerializable()
 class Person extends Object with _$PersonSerializerMixin {
   final String firstName, middleName, lastName;
   final DateTime dateOfBirth;
+  final House house;
 
-  Person(this.firstName, this.lastName, {this.middleName, this.dateOfBirth});
+  Person(this.firstName, this.lastName, this.house,
+      {this.middleName, this.dateOfBirth});
 
   factory Person.fromJson(Map<String, dynamic> json) => _$PersonFromJson(json);
 
@@ -29,16 +33,21 @@ class Person extends Object with _$PersonSerializerMixin {
       dateOfBirth == other.dateOfBirth;
 }
 
+enum Category { top, bottom, strange, charmed, up, down }
+
 @JsonSerializable()
 class Order extends Object with _$OrderSerializerMixin {
   int count;
   bool isRushed;
+
+  @JsonKey(nullable: false)
+  final Category category;
   final UnmodifiableListView<Item> items;
   Platform platform;
 
   int get price => items.fold(0, (total, item) => item.price + total);
 
-  Order([Iterable<Item> items])
+  Order(this.category, [Iterable<Item> items])
       : this.items = new UnmodifiableListView<Item>(
             new List<Item>.unmodifiable(items ?? const <Item>[]));