[json] add datetime support

pkg/json/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 0.20.3
+
+- Add support for DateTime, serializing it to an ISO-8601 String.
+
 # 0.20.2
 
 - Fix generated code syntax error when defining fields containing the dollar sign `$` by using raw strings.

pkg/json/README.md

@@ -55,6 +55,8 @@ class Manager extends User {
 
 All native JSON types are supported (`int`, `double`, `String`, `bool`, `Null`).
 
+Supports `DateTime`, serializing it to an ISO-8601 String.
+
 The core collection types `List`, `Set`, and `Map` are also supported, if their
 elements are supported types. For elements which require more than just a cast,
 the type must be statically provided through a generic type argument on the

pkg/json/lib/json.dart

@@ -378,6 +378,16 @@ mixin _FromJson on _Shared {
             ' as ',
             type.code,
           ]);
+        case 'DateTime':
+          return RawCode.fromParts([
+            if (nullCheck != null) nullCheck,
+            await builder.resolveIdentifier(_dartCore, 'DateTime'),
+            '.parse(',
+            jsonReference,
+            ' as ',
+            introspectionData.stringCode,
+            ')'
+          ]);
       }
     }
 
@@ -511,7 +521,9 @@ mixin _ToJson on _Shared {
               if (doNullCheck) '!',
             ]),
             builder,
-            introspectionData),
+            introspectionData,
+            // We already are doing the null check.
+            omitNullCheck: true),
         ';\n    ',
       ]);
       if (doNullCheck) {
@@ -570,12 +582,16 @@ mixin _ToJson on _Shared {
   }
 
   /// Returns a [Code] object which is an expression that converts an instance
-  /// of type [type] (referenced by [valueReference]) into a JSON map.
+  /// of type [rawType] (referenced by [valueReference]) into a JSON map.
+  ///
+  /// Null checks will be inserted if [rawType] is  nullable, unless
+  /// [omitNullCheck] is `true`.
   Future<Code> _convertTypeToJson(
       TypeAnnotation rawType,
       Code valueReference,
       DefinitionBuilder builder,
-      _SharedIntrospectionData introspectionData) async {
+      _SharedIntrospectionData introspectionData,
+      {bool omitNullCheck = false}) async {
     final type = _checkNamedType(rawType, builder);
     if (type == null) {
       return RawCode.fromString(
@@ -589,7 +605,7 @@ mixin _ToJson on _Shared {
           "throw 'Unable to serialize type ${type.code.debugString}'");
     }
 
-    var nullCheck = type.isNullable
+    var nullCheck = type.isNullable && !omitNullCheck
         ? RawCode.fromParts([
             valueReference,
             // `null` is a reserved word, we can just use it.
@@ -624,6 +640,8 @@ mixin _ToJson on _Shared {
           ]);
         case 'int' || 'double' || 'num' || 'String' || 'bool':
           return valueReference;
+        case 'DateTime':
+          return RawCode.fromParts([if (nullCheck != null) nullCheck, valueReference, '.toIso8601String()']);
       }
     }
 

pkg/json/pubspec.yaml

@@ -5,7 +5,7 @@ description: >
   `toJson` encoding method.
 
 repository: https://github.com/dart-lang/sdk/tree/main/pkg/json
-version: 0.20.2
+version: 0.20.3
 environment:
   sdk: ^3.6.0-edge
 dependencies:

pkg/json/test/json_codable_test.dart

@@ -16,6 +16,7 @@ void main() {
         'intField': 10,
         'doubleField': 12.5,
         'numField': 11,
+        'dateTimeField': '2024-11-11T03:42:29.108308',
         'listOfSerializableField': [
           {'x': 1},
         ],
@@ -33,6 +34,7 @@ void main() {
       expect(a.intField, 10);
       expect(a.doubleField, 12.5);
       expect(a.numField, 11);
+      expect(a.dateTimeField, DateTime.parse('2024-11-11T03:42:29.108308'));
       expect(a.listOfSerializableField.single.x, 1);
       expect(a.setOfSerializableField.single.x, 2);
       expect(a.mapOfSerializableField['c']!.x, 3);
@@ -47,6 +49,7 @@ void main() {
         'nullableIntField': 9,
         'nullableDoubleField': 11.5,
         'nullableNumField': 11.1,
+        'nullableDateTimeField': '2024-11-11T03:42:29.108308',
         'nullableListOfSerializableField': [
           {'x': 1},
         ],
@@ -64,6 +67,8 @@ void main() {
       expect(b.nullableIntField, 9);
       expect(b.nullableDoubleField, 11.5);
       expect(b.nullableNumField, 11.1);
+      expect(b.nullableDateTimeField,
+          DateTime.parse('2024-11-11T03:42:29.108308'));
       expect(b.nullableListOfSerializableField!.single.x, 1);
       expect(b.nullableSetOfSerializableField!.single.x, 2);
       expect(b.nullableMapOfSerializableField!['d']!.x, 3);
@@ -78,6 +83,7 @@ void main() {
         'nullableIntField': null,
         'nullableDoubleField': null,
         'nullableNumField': null,
+        'nullableDateTimeField': null,
         'nullableListOfSerializableField': null,
         'nullableSetOfSerializableField': null,
         'nullableMapOfSerializableField': null,
@@ -87,6 +93,7 @@ void main() {
       expect(b.nullableIntField, null);
       expect(b.nullableDoubleField, null);
       expect(b.nullableNumField, null);
+      expect(b.nullableDateTimeField, null);
       expect(b.nullableListOfSerializableField, null);
       expect(b.nullableMapOfSerializableField, null);
       expect(b.nullableSetOfSerializableField, null);
@@ -101,6 +108,7 @@ void main() {
       expect(b.nullableIntField, null);
       expect(b.nullableDoubleField, null);
       expect(b.nullableNumField, null);
+      expect(b.nullableDateTimeField, null);
       expect(b.nullableListOfSerializableField, null);
       expect(b.nullableMapOfSerializableField, null);
       expect(b.nullableSetOfSerializableField, null);
@@ -122,6 +130,7 @@ void main() {
 
     test('collections of nullable objects', () {
       var json = {
+        'listOfNullableDates': [null, '2024-11-11T03:42:29.108308'],
         'listOfNullableInts': [null, 1],
         'listOfNullableSerializables': [
           {'x': 1},
@@ -131,6 +140,10 @@ void main() {
           null,
           {'a': 1, 'b': null},
         ],
+        'setOfNullableDates': [
+          null,
+          '2024-11-12T03:42:29.108308',
+        ],
         'setOfNullableInts': [
           null,
           2,
@@ -146,6 +159,10 @@ void main() {
             'b': null,
           },
         ],
+        'mapOfNullableDates': {
+          'a': '2024-11-13T03:42:29.108308',
+          'b': null,
+        },
         'mapOfNullableInts': {
           'a': 3,
           'b': null,
@@ -161,6 +178,8 @@ void main() {
       };
 
       var e = E.fromJson(json);
+      expect(e.listOfNullableDates,
+          equals([null, DateTime.parse('2024-11-11T03:42:29.108308')]));
       expect(e.listOfNullableInts, equals([null, 1]));
       expect(e.listOfNullableSerializables.first!.x, 1);
       expect(e.listOfNullableSerializables[1], null);
@@ -170,6 +189,8 @@ void main() {
             null,
             {'a': 1, 'b': null},
           ]));
+      expect(e.setOfNullableDates,
+          equals([null, DateTime.parse('2024-11-12T03:42:29.108308')]));
       expect(e.setOfNullableInts, equals({null, 2}));
       expect(e.setOfNullableSerializables.first!.x, 2);
       expect(e.setOfNullableSerializables.elementAt(1), null);
@@ -182,6 +203,12 @@ void main() {
               'b': null,
             },
           }));
+      expect(
+          e.mapOfNullableDates,
+          equals({
+            'a': DateTime.parse('2024-11-13T03:42:29.108308'),
+            'b': null,
+          }));
       expect(
           e.mapOfNullableInts,
           equals({
@@ -223,6 +250,8 @@ class A {
 
   final num numField;
 
+  final DateTime dateTimeField;
+
   final List<C> listOfSerializableField;
 
   final Set<C> setOfSerializableField;
@@ -242,6 +271,8 @@ class B {
 
   final num? nullableNumField;
 
+  final DateTime? nullableDateTimeField;
+
   final List<C>? nullableListOfSerializableField;
 
   final Set<C>? nullableSetOfSerializableField;
@@ -261,18 +292,24 @@ class D extends C {
 
 @JsonCodable()
 class E {
+  final List<DateTime?> listOfNullableDates;
+
   final List<int?> listOfNullableInts;
 
   final List<C?> listOfNullableSerializables;
 
   final List<Map<String, int?>?> listOfNullableMapsOfNullableInts;
 
+  final Set<DateTime?> setOfNullableDates;
+
   final Set<int?> setOfNullableInts;
 
   final Set<C?> setOfNullableSerializables;
 
   final Set<Map<String, int?>?> setOfNullableMapsOfNullableInts;
 
+  final Map<String, DateTime?> mapOfNullableDates;
+
   final Map<String, int?> mapOfNullableInts;
 
   final Map<String, C?> mapOfNullableSerializables;