diff --git a/_test_yaml/test/src/build_config.g.dart b/_test_yaml/test/src/build_config.g.dart
index 61e578ec4..e4d832e78 100644
--- a/_test_yaml/test/src/build_config.g.dart
+++ b/_test_yaml/test/src/build_config.g.dart
@@ -103,28 +103,23 @@ Builder _$BuilderFromJson(Map json) => $checkedCreate(
       },
     );
 
-Map<String, dynamic> _$BuilderToJson(Builder instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('target', instance.target);
-  writeNotNull('import', instance.import);
-  writeNotNull('is_optional', instance.isOptional);
-  writeNotNull('configLocation', instance.configLocation?.toString());
-  writeNotNull('auto_apply', _$AutoApplyEnumMap[instance.autoApply]);
-  writeNotNull('build_to', _$BuildToEnumMap[instance.buildTo]);
-  writeNotNull('defaultEnumTest', _$AutoApplyEnumMap[instance.defaultEnumTest]);
-  val['builder_factories'] = instance.builderFactories;
-  writeNotNull('applies_builders', instance.appliesBuilders);
-  writeNotNull('required_inputs', instance.requiredInputs);
-  writeNotNull('build_extensions', instance.buildExtensions);
-  return val;
-}
+Map<String, dynamic> _$BuilderToJson(Builder instance) => <String, dynamic>{
+      if (instance.target case final value?) 'target': value,
+      if (instance.import case final value?) 'import': value,
+      if (instance.isOptional case final value?) 'is_optional': value,
+      if (instance.configLocation?.toString() case final value?)
+        'configLocation': value,
+      if (_$AutoApplyEnumMap[instance.autoApply] case final value?)
+        'auto_apply': value,
+      if (_$BuildToEnumMap[instance.buildTo] case final value?)
+        'build_to': value,
+      if (_$AutoApplyEnumMap[instance.defaultEnumTest] case final value?)
+        'defaultEnumTest': value,
+      'builder_factories': instance.builderFactories,
+      if (instance.appliesBuilders case final value?) 'applies_builders': value,
+      if (instance.requiredInputs case final value?) 'required_inputs': value,
+      if (instance.buildExtensions case final value?) 'build_extensions': value,
+    };
 
 const _$BuildToEnumMap = {
   BuildTo.cache: 'cache',
diff --git a/example/lib/example.g.dart b/example/lib/example.g.dart
index b4cf7de11..f497bc0e7 100644
--- a/example/lib/example.g.dart
+++ b/example/lib/example.g.dart
@@ -19,24 +19,14 @@ Person _$PersonFromJson(Map<String, dynamic> json) => Person(
           .toList(),
     );
 
-Map<String, dynamic> _$PersonToJson(Person instance) {
-  final val = <String, dynamic>{
-    'firstName': instance.firstName,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('middleName', instance.middleName);
-  val['lastName'] = instance.lastName;
-  val['date-of-birth'] = instance.dateOfBirth.toIso8601String();
-  val['last-order'] = instance.lastOrder?.toIso8601String();
-  val['orders'] = instance.orders;
-  return val;
-}
+Map<String, dynamic> _$PersonToJson(Person instance) => <String, dynamic>{
+      'firstName': instance.firstName,
+      if (instance.middleName case final value?) 'middleName': value,
+      'lastName': instance.lastName,
+      'date-of-birth': instance.dateOfBirth.toIso8601String(),
+      'last-order': instance.lastOrder?.toIso8601String(),
+      'orders': instance.orders,
+    };
 
 Order _$OrderFromJson(Map<String, dynamic> json) => Order(
       Order._dateTimeFromEpochUs((json['date'] as num).toInt()),
@@ -50,23 +40,16 @@ Order _$OrderFromJson(Map<String, dynamic> json) => Order(
       ..prepTime =
           Order._durationFromMilliseconds((json['prep-time'] as num?)?.toInt());
 
-Map<String, dynamic> _$OrderToJson(Order instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('count', instance.count);
-  writeNotNull('itemNumber', instance.itemNumber);
-  writeNotNull('isRushed', instance.isRushed);
-  writeNotNull('item', instance.item);
-  writeNotNull('prep-time', Order._durationToMilliseconds(instance.prepTime));
-  writeNotNull('date', Order._dateTimeToEpochUs(instance.date));
-  return val;
-}
+Map<String, dynamic> _$OrderToJson(Order instance) => <String, dynamic>{
+      if (instance.count case final value?) 'count': value,
+      if (instance.itemNumber case final value?) 'itemNumber': value,
+      if (instance.isRushed case final value?) 'isRushed': value,
+      if (instance.item case final value?) 'item': value,
+      if (Order._durationToMilliseconds(instance.prepTime) case final value?)
+        'prep-time': value,
+      if (Order._dateTimeToEpochUs(instance.date) case final value?)
+        'date': value,
+    };
 
 Item _$ItemFromJson(Map<String, dynamic> json) => Item()
   ..count = (json['count'] as num?)?.toInt()
diff --git a/example/test/example_test.dart b/example/test/example_test.dart
index e2abf3424..99dc2ed53 100644
--- a/example/test/example_test.dart
+++ b/example/test/example_test.dart
@@ -10,8 +10,12 @@ import 'package:test/test.dart';
 
 void main() {
   test('JsonSerializable', () {
-    final person = Person('Inigo', 'Montoya', DateTime(1560, 5, 5))
-      ..orders = [Order(DateTime.now())..item = (Item()..count = 42)];
+    final person = Person(
+      'Inigo',
+      'Montoya',
+      DateTime(1560, 5, 5),
+      middleName: 'Bob',
+    )..orders = [Order(DateTime.now())..item = (Item()..count = 42)];
 
     final personJson = loudEncode(person);
 
diff --git a/json_serializable/CHANGELOG.md b/json_serializable/CHANGELOG.md
index 222e369d9..7c14862e2 100644
--- a/json_serializable/CHANGELOG.md
+++ b/json_serializable/CHANGELOG.md
@@ -1,5 +1,6 @@
-## 6.8.1-wip
+## 6.9.0-wip
 
+- Use conditional map syntax to clean up `null` handling in `toJson` functions.
 - Require Dart 3.5
 
 ## 6.8.0
diff --git a/json_serializable/lib/src/constants.dart b/json_serializable/lib/src/constants.dart
index 9949b77cc..a151ff034 100644
--- a/json_serializable/lib/src/constants.dart
+++ b/json_serializable/lib/src/constants.dart
@@ -5,8 +5,7 @@
 /// Name used for closure argument when generating calls to `map`.
 const closureArg = 'e';
 
-const generatedLocalVarName = 'val';
-const toJsonMapHelperName = 'writeNotNull';
+const generatedLocalVarName = 'value';
 
 const converterOrKeyInstructions = r'''
 * Use `JsonConverter`
diff --git a/json_serializable/lib/src/encoder_helper.dart b/json_serializable/lib/src/encoder_helper.dart
index 05d4c714d..4e876b757 100644
--- a/json_serializable/lib/src/encoder_helper.dart
+++ b/json_serializable/lib/src/encoder_helper.dart
@@ -97,18 +97,22 @@ mixin EncodeHelper implements HelperCore {
 
     if (config.genericArgumentFactories) _writeGenericArgumentFactories(buffer);
 
-    buffer.write(') ');
+    buffer
+      ..write(') ')
+      ..writeln('=> <String, dynamic>{')
+      ..writeAll(accessibleFields.map((field) {
+        final access = _fieldAccess(field);
 
-    final canWriteAllJsonValuesWithoutNullCheck =
-        accessibleFields.every(_canWriteJsonWithoutNullCheck);
+        final keyExpression = safeNameAccess(field);
+        final valueExpression = _serializeField(field, access);
 
-    if (canWriteAllJsonValuesWithoutNullCheck) {
-      // write simple `toJson` method that includes all keys...
-      _writeToJsonSimple(buffer, accessibleFields);
-    } else {
-      // At least one field should be excluded if null
-      _writeToJsonWithNullChecks(buffer, accessibleFields);
-    }
+        final keyValuePair = _canWriteJsonWithoutNullCheck(field)
+            ? '$keyExpression: $valueExpression'
+            : 'if ($valueExpression case final $generatedLocalVarName?) '
+                '$keyExpression: $generatedLocalVarName';
+        return '        $keyValuePair,\n';
+      }))
+      ..writeln('};');
 
     yield buffer.toString();
   }
@@ -125,81 +129,8 @@ mixin EncodeHelper implements HelperCore {
     }
   }
 
-  void _writeToJsonSimple(StringBuffer buffer, Iterable<FieldElement> fields) {
-    buffer
-      ..writeln('=> <String, dynamic>{')
-      ..writeAll(fields.map((field) {
-        final access = _fieldAccess(field);
-        final value =
-            '${safeNameAccess(field)}: ${_serializeField(field, access)}';
-        return '        $value,\n';
-      }))
-      ..writeln('};');
-  }
-
   static const _toJsonParamName = 'instance';
 
-  void _writeToJsonWithNullChecks(
-    StringBuffer buffer,
-    Iterable<FieldElement> fields,
-  ) {
-    buffer
-      ..writeln('{')
-      ..writeln('    final $generatedLocalVarName = <String, dynamic>{');
-
-    // Note that the map literal is left open above. As long as target fields
-    // don't need to be intercepted by the `only if null` logic, write them
-    // to the map literal directly. In theory, should allow more efficient
-    // serialization.
-    var directWrite = true;
-
-    for (final field in fields) {
-      var safeFieldAccess = _fieldAccess(field);
-      final safeJsonKeyString = safeNameAccess(field);
-
-      // If `fieldName` collides with one of the local helpers, prefix
-      // access with `this.`.
-      if (safeFieldAccess == generatedLocalVarName ||
-          safeFieldAccess == toJsonMapHelperName) {
-        safeFieldAccess = 'this.$safeFieldAccess';
-      }
-
-      final expression = _serializeField(field, safeFieldAccess);
-      if (_canWriteJsonWithoutNullCheck(field)) {
-        if (directWrite) {
-          buffer.writeln('      $safeJsonKeyString: $expression,');
-        } else {
-          buffer.writeln(
-              '    $generatedLocalVarName[$safeJsonKeyString] = $expression;');
-        }
-      } else {
-        if (directWrite) {
-          // close the still-open map literal
-          buffer
-            ..writeln('    };')
-            ..writeln()
-
-            // write the helper to be used by all following null-excluding
-            // fields
-            ..writeln('''
-    void $toJsonMapHelperName(String key, dynamic value) {
-      if (value != null) {
-        $generatedLocalVarName[key] = value;
-      }
-    }
-''');
-          directWrite = false;
-        }
-        buffer.writeln(
-            '    $toJsonMapHelperName($safeJsonKeyString, $expression);');
-      }
-    }
-
-    buffer
-      ..writeln('    return $generatedLocalVarName;')
-      ..writeln('  }');
-  }
-
   String _serializeField(FieldElement field, String accessExpression) {
     try {
       return getHelperContext(field)
diff --git a/json_serializable/pubspec.yaml b/json_serializable/pubspec.yaml
index 1adf0afb2..854f2c7fd 100644
--- a/json_serializable/pubspec.yaml
+++ b/json_serializable/pubspec.yaml
@@ -1,5 +1,5 @@
 name: json_serializable
-version: 6.8.1-wip
+version: 6.9.0-wip
 description: >-
   Automatically generate code for converting to and from JSON by annotating
   Dart classes.
diff --git a/json_serializable/test/custom_configuration_test.dart b/json_serializable/test/custom_configuration_test.dart
index a717b7bb8..4ac5d02ca 100644
--- a/json_serializable/test/custom_configuration_test.dart
+++ b/json_serializable/test/custom_configuration_test.dart
@@ -214,7 +214,6 @@ Map<String, dynamic> _$TrivialNestedNonNullableToJson(
     test('some', () async {
       final output = await runForElementNamed('IncludeIfNullAll');
       expect(output, isNot(contains(generatedLocalVarName)));
-      expect(output, isNot(contains(toJsonMapHelperName)));
     });
   });
 }
diff --git a/json_serializable/test/integration/converter_examples.g.dart b/json_serializable/test/integration/converter_examples.g.dart
index 2829672a9..f19c8fc2e 100644
--- a/json_serializable/test/integration/converter_examples.g.dart
+++ b/json_serializable/test/integration/converter_examples.g.dart
@@ -26,33 +26,26 @@ Issue1202RegressionClass _$Issue1202RegressionClassFromJson(
     );
 
 Map<String, dynamic> _$Issue1202RegressionClassToJson(
-    Issue1202RegressionClass instance) {
-  final val = <String, dynamic>{
-    'valueWithFunctions':
-        Issue1202RegressionClass._toJson(instance.valueWithFunctions),
-    'notNullableValueWithConverter':
-        const _Issue1202RegressionNotNullConverter()
-            .toJson(instance.notNullableValueWithConverter),
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('value', _$Issue1202RegressionEnumEnumMap[instance.value]);
-  writeNotNull('normalNullableValue', instance.normalNullableValue);
-  writeNotNull(
-      'notNullableValueWithNullableConverter',
-      const _Issue1202RegressionConverter()
-          .toJson(instance.notNullableValueWithNullableConverter));
-  writeNotNull(
-      'valueWithNullableFunctions',
-      Issue1202RegressionClass._toJsonNullable(
-          instance.valueWithNullableFunctions));
-  return val;
-}
+        Issue1202RegressionClass instance) =>
+    <String, dynamic>{
+      'valueWithFunctions':
+          Issue1202RegressionClass._toJson(instance.valueWithFunctions),
+      'notNullableValueWithConverter':
+          const _Issue1202RegressionNotNullConverter()
+              .toJson(instance.notNullableValueWithConverter),
+      if (_$Issue1202RegressionEnumEnumMap[instance.value] case final value?)
+        'value': value,
+      if (instance.normalNullableValue case final value?)
+        'normalNullableValue': value,
+      if (const _Issue1202RegressionConverter()
+              .toJson(instance.notNullableValueWithNullableConverter)
+          case final value?)
+        'notNullableValueWithNullableConverter': value,
+      if (Issue1202RegressionClass._toJsonNullable(
+              instance.valueWithNullableFunctions)
+          case final value?)
+        'valueWithNullableFunctions': value,
+    };
 
 const _$Issue1202RegressionEnumEnumMap = {
   Issue1202RegressionEnum.normalValue: 42,
@@ -65,21 +58,13 @@ Regression1229 _$Regression1229FromJson(Map<String, dynamic> json) =>
           json['date'], const DateTimeConverter().fromJson),
     );
 
-Map<String, dynamic> _$Regression1229ToJson(Regression1229 instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull(
-      'date',
-      _$JsonConverterToJson<String, DateTime>(
-          instance.date, const DateTimeConverter().toJson));
-  return val;
-}
+Map<String, dynamic> _$Regression1229ToJson(Regression1229 instance) =>
+    <String, dynamic>{
+      if (_$JsonConverterToJson<String, DateTime>(
+              instance.date, const DateTimeConverter().toJson)
+          case final value?)
+        'date': value,
+    };
 
 Value? _$JsonConverterFromJson<Json, Value>(
   Object? json,
diff --git a/json_serializable/test/integration/create_per_field_to_json_example.g.dart b/json_serializable/test/integration/create_per_field_to_json_example.g.dart
index 1c4b0fe88..28f3443a5 100644
--- a/json_serializable/test/integration/create_per_field_to_json_example.g.dart
+++ b/json_serializable/test/integration/create_per_field_to_json_example.g.dart
@@ -45,26 +45,17 @@ abstract class _$ModelPerFieldToJson {
   static Object? nestedExcludeIfNull(Nested? instance) => instance?.toJson();
 }
 
-Map<String, dynamic> _$ModelToJson(Model instance) {
-  final val = <String, dynamic>{
-    'firstName': instance.firstName,
-    'lastName': instance.lastName,
-    'enumValue': _$EnumValueEnumMap[instance.enumValue],
-    'nested': instance.nested?.toJson(),
-    'nestedGeneric': instance.nestedGeneric?.toJson(
-      (value) => value,
-    ),
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('nestedExcludeIfNull', instance.nestedExcludeIfNull?.toJson());
-  return val;
-}
+Map<String, dynamic> _$ModelToJson(Model instance) => <String, dynamic>{
+      'firstName': instance.firstName,
+      'lastName': instance.lastName,
+      'enumValue': _$EnumValueEnumMap[instance.enumValue],
+      'nested': instance.nested?.toJson(),
+      'nestedGeneric': instance.nestedGeneric?.toJson(
+        (value) => value,
+      ),
+      if (instance.nestedExcludeIfNull?.toJson() case final value?)
+        'nestedExcludeIfNull': value,
+    };
 
 const _$EnumValueEnumMap = {
   EnumValue.first: '1',
diff --git a/json_serializable/test/integration/json_enum_example.g.dart b/json_serializable/test/integration/json_enum_example.g.dart
index 6408e9e1d..95ae41b17 100644
--- a/json_serializable/test/integration/json_enum_example.g.dart
+++ b/json_serializable/test/integration/json_enum_example.g.dart
@@ -53,19 +53,13 @@ Issue1226Regression _$Issue1226RegressionFromJson(Map<String, dynamic> json) =>
           _$Issue1145RegressionEnumEnumMap, json['durationType']),
     );
 
-Map<String, dynamic> _$Issue1226RegressionToJson(Issue1226Regression instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull(
-      'durationType', _$Issue1145RegressionEnumEnumMap[instance.durationType]);
-  return val;
-}
+Map<String, dynamic> _$Issue1226RegressionToJson(
+        Issue1226Regression instance) =>
+    <String, dynamic>{
+      if (_$Issue1145RegressionEnumEnumMap[instance.durationType]
+          case final value?)
+        'durationType': value,
+    };
 
 const _$StandAloneEnumEnumMap = {
   StandAloneEnum.alpha: 'a',
diff --git a/json_serializable/test/integration/json_test_example.g.dart b/json_serializable/test/integration/json_test_example.g.dart
index ec12eb554..bf56859ed 100644
--- a/json_serializable/test/integration/json_test_example.g.dart
+++ b/json_serializable/test/integration/json_test_example.g.dart
@@ -85,26 +85,17 @@ Order _$OrderFromJson(Map<String, dynamic> json) {
         StatusCode.success;
 }
 
-Map<String, dynamic> _$OrderToJson(Order instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('count', instance.count);
-  val['isRushed'] = instance.isRushed;
-  val['duration'] = instance.duration?.inMicroseconds;
-  val['category'] = _$CategoryEnumMap[instance.category];
-  val['items'] = instance.items;
-  val['platform'] = instance.platform;
-  val['altPlatforms'] = instance.altPlatforms;
-  val['homepage'] = instance.homepage?.toString();
-  val['status_code'] = _$StatusCodeEnumMap[instance.statusCode];
-  return val;
-}
+Map<String, dynamic> _$OrderToJson(Order instance) => <String, dynamic>{
+      if (instance.count case final value?) 'count': value,
+      'isRushed': instance.isRushed,
+      'duration': instance.duration?.inMicroseconds,
+      'category': _$CategoryEnumMap[instance.category],
+      'items': instance.items,
+      'platform': instance.platform,
+      'altPlatforms': instance.altPlatforms,
+      'homepage': instance.homepage?.toString(),
+      'status_code': _$StatusCodeEnumMap[instance.statusCode],
+    };
 
 const _$StatusCodeEnumMap = {
   StatusCode.success: 200,
@@ -125,24 +116,13 @@ Item _$ItemFromJson(Map<String, dynamic> json) => Item(
           .toList()
       ..geoPoint = _fromJsonGeoPoint(json['geoPoint'] as Map<String, dynamic>?);
 
-Map<String, dynamic> _$ItemToJson(Item instance) {
-  final val = <String, dynamic>{
-    'price': instance.price,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('item-number', instance.itemNumber);
-  val['saleDates'] =
-      instance.saleDates?.map((e) => e.toIso8601String()).toList();
-  val['rates'] = instance.rates;
-  val['geoPoint'] = _toJsonGeoPoint(instance.geoPoint);
-  return val;
-}
+Map<String, dynamic> _$ItemToJson(Item instance) => <String, dynamic>{
+      'price': instance.price,
+      if (instance.itemNumber case final value?) 'item-number': value,
+      'saleDates': instance.saleDates?.map((e) => e.toIso8601String()).toList(),
+      'rates': instance.rates,
+      'geoPoint': _toJsonGeoPoint(instance.geoPoint),
+    };
 
 Numbers _$NumbersFromJson(Map<String, dynamic> json) => Numbers()
   ..ints =
diff --git a/json_serializable/test/integration/json_test_example.g_any_map.g.dart b/json_serializable/test/integration/json_test_example.g_any_map.g.dart
index 5fe79152e..ef2ad4f95 100644
--- a/json_serializable/test/integration/json_test_example.g_any_map.g.dart
+++ b/json_serializable/test/integration/json_test_example.g_any_map.g.dart
@@ -85,26 +85,17 @@ Order _$OrderFromJson(Map json) {
         StatusCode.success;
 }
 
-Map<String, dynamic> _$OrderToJson(Order instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('count', instance.count);
-  val['isRushed'] = instance.isRushed;
-  val['duration'] = instance.duration?.inMicroseconds;
-  val['category'] = _$CategoryEnumMap[instance.category];
-  val['items'] = instance.items;
-  val['platform'] = instance.platform;
-  val['altPlatforms'] = instance.altPlatforms;
-  val['homepage'] = instance.homepage?.toString();
-  val['status_code'] = _$StatusCodeEnumMap[instance.statusCode];
-  return val;
-}
+Map<String, dynamic> _$OrderToJson(Order instance) => <String, dynamic>{
+      if (instance.count case final value?) 'count': value,
+      'isRushed': instance.isRushed,
+      'duration': instance.duration?.inMicroseconds,
+      'category': _$CategoryEnumMap[instance.category],
+      'items': instance.items,
+      'platform': instance.platform,
+      'altPlatforms': instance.altPlatforms,
+      'homepage': instance.homepage?.toString(),
+      'status_code': _$StatusCodeEnumMap[instance.statusCode],
+    };
 
 const _$StatusCodeEnumMap = {
   StatusCode.success: 200,
@@ -125,24 +116,13 @@ Item _$ItemFromJson(Map json) => Item(
           .toList()
       ..geoPoint = _fromJsonGeoPoint(json['geoPoint'] as Map<String, dynamic>?);
 
-Map<String, dynamic> _$ItemToJson(Item instance) {
-  final val = <String, dynamic>{
-    'price': instance.price,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('item-number', instance.itemNumber);
-  val['saleDates'] =
-      instance.saleDates?.map((e) => e.toIso8601String()).toList();
-  val['rates'] = instance.rates;
-  val['geoPoint'] = _toJsonGeoPoint(instance.geoPoint);
-  return val;
-}
+Map<String, dynamic> _$ItemToJson(Item instance) => <String, dynamic>{
+      'price': instance.price,
+      if (instance.itemNumber case final value?) 'item-number': value,
+      'saleDates': instance.saleDates?.map((e) => e.toIso8601String()).toList(),
+      'rates': instance.rates,
+      'geoPoint': _toJsonGeoPoint(instance.geoPoint),
+    };
 
 Numbers _$NumbersFromJson(Map json) => Numbers()
   ..ints =
diff --git a/json_serializable/test/kitchen_sink/kitchen_sink.g_exclude_null.g.dart b/json_serializable/test/kitchen_sink/kitchen_sink.g_exclude_null.g.dart
index a3a8f8550..39b0eb184 100644
--- a/json_serializable/test/kitchen_sink/kitchen_sink.g_exclude_null.g.dart
+++ b/json_serializable/test/kitchen_sink/kitchen_sink.g_exclude_null.g.dart
@@ -98,69 +98,63 @@ KitchenSink _$KitchenSinkFromJson(Map<String, dynamic> json) => KitchenSink(
         ),
       );
 
-Map<String, dynamic> _$KitchenSinkToJson(KitchenSink instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('no-42', instance.ctorValidatedNo42);
-  writeNotNull('dateTime', instance.dateTime?.toIso8601String());
-  writeNotNull('bigInt', instance.bigInt?.toString());
-  writeNotNull('iterable', instance.iterable?.toList());
-  val['dynamicIterable'] = instance.dynamicIterable.toList();
-  val['objectIterable'] = instance.objectIterable.toList();
-  val['intIterable'] = instance.intIterable.toList();
-  val['set'] = instance.set.toList();
-  val['dynamicSet'] = instance.dynamicSet.toList();
-  val['objectSet'] = instance.objectSet.toList();
-  val['intSet'] = instance.intSet.toList();
-  val['dateTimeSet'] =
-      instance.dateTimeSet.map((e) => e.toIso8601String()).toList();
-  val['datetime-iterable'] =
-      instance.dateTimeIterable.map((e) => e.toIso8601String()).toList();
-  val['list'] = instance.list;
-  val['dynamicList'] = instance.dynamicList;
-  val['objectList'] = instance.objectList;
-  val['intList'] = instance.intList;
-  val['dateTimeList'] =
-      instance.dateTimeList.map((e) => e.toIso8601String()).toList();
-  val['nullableSimpleObjectList'] = instance.nullableSimpleObjectList;
-  val['map'] = instance.map;
-  val['stringStringMap'] = instance.stringStringMap;
-  val['dynamicIntMap'] = instance.dynamicIntMap;
-  val['objectDateTimeMap'] = instance.objectDateTimeMap
-      .map((k, e) => MapEntry(k, e.toIso8601String()));
-  val['nullableSimpleObjectMap'] = instance.nullableSimpleObjectMap;
-  val['crazyComplex'] = instance.crazyComplex
-      .map((e) => e?.map((k, e) => MapEntry(
-          k,
-          e?.map((k, e) => MapEntry(
+Map<String, dynamic> _$KitchenSinkToJson(KitchenSink instance) =>
+    <String, dynamic>{
+      if (instance.ctorValidatedNo42 case final value?) 'no-42': value,
+      if (instance.dateTime?.toIso8601String() case final value?)
+        'dateTime': value,
+      if (instance.bigInt?.toString() case final value?) 'bigInt': value,
+      if (instance.iterable?.toList() case final value?) 'iterable': value,
+      'dynamicIterable': instance.dynamicIterable.toList(),
+      'objectIterable': instance.objectIterable.toList(),
+      'intIterable': instance.intIterable.toList(),
+      'set': instance.set.toList(),
+      'dynamicSet': instance.dynamicSet.toList(),
+      'objectSet': instance.objectSet.toList(),
+      'intSet': instance.intSet.toList(),
+      'dateTimeSet':
+          instance.dateTimeSet.map((e) => e.toIso8601String()).toList(),
+      'datetime-iterable':
+          instance.dateTimeIterable.map((e) => e.toIso8601String()).toList(),
+      'list': instance.list,
+      'dynamicList': instance.dynamicList,
+      'objectList': instance.objectList,
+      'intList': instance.intList,
+      'dateTimeList':
+          instance.dateTimeList.map((e) => e.toIso8601String()).toList(),
+      'nullableSimpleObjectList': instance.nullableSimpleObjectList,
+      'map': instance.map,
+      'stringStringMap': instance.stringStringMap,
+      'dynamicIntMap': instance.dynamicIntMap,
+      'objectDateTimeMap': instance.objectDateTimeMap
+          .map((k, e) => MapEntry(k, e.toIso8601String())),
+      'nullableSimpleObjectMap': instance.nullableSimpleObjectMap,
+      'crazyComplex': instance.crazyComplex
+          .map((e) => e?.map((k, e) => MapEntry(
               k,
-              e
-                  ?.map((e) => e?.map((e) => e.toIso8601String()).toList())
-                  .toList())))))
-      .toList();
-  val['val'] = instance.val;
-  writeNotNull('writeNotNull', instance.writeNotNull);
-  writeNotNull(r'$string', instance.string);
-  val['simpleObject'] = instance.simpleObject;
-  val['strictKeysObject'] = instance.strictKeysObject;
-  writeNotNull('validatedPropertyNo42', instance.validatedPropertyNo42);
-  writeNotNull(
-      'recordField',
-      instance.recordField == null
-          ? null
-          : <String, dynamic>{
-              r'$1': instance.recordField!.$1,
-              r'$2': instance.recordField!.$2,
-              'truth': instance.recordField!.truth,
-            });
-  return val;
-}
+              e?.map((k, e) => MapEntry(
+                  k,
+                  e
+                      ?.map((e) => e?.map((e) => e.toIso8601String()).toList())
+                      .toList())))))
+          .toList(),
+      'val': instance.val,
+      if (instance.writeNotNull case final value?) 'writeNotNull': value,
+      if (instance.string case final value?) r'$string': value,
+      'simpleObject': instance.simpleObject,
+      'strictKeysObject': instance.strictKeysObject,
+      if (instance.validatedPropertyNo42 case final value?)
+        'validatedPropertyNo42': value,
+      if (instance.recordField == null
+              ? null
+              : <String, dynamic>{
+                  r'$1': instance.recordField!.$1,
+                  r'$2': instance.recordField!.$2,
+                  'truth': instance.recordField!.truth,
+                }
+          case final value?)
+        'recordField': value,
+    };
 
 $Rec? _$recordConvertNullable<$Rec>(
   Object? value,
@@ -208,50 +202,47 @@ JsonConverterTestClass _$JsonConverterTestClassFromJson(
     );
 
 Map<String, dynamic> _$JsonConverterTestClassToJson(
-    JsonConverterTestClass instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('duration',
-      const DurationMillisecondConverter().toJson(instance.duration));
-  val['durationList'] = instance.durationList
-      .map(const DurationMillisecondConverter().toJson)
-      .toList();
-  val['bigInt'] = const BigIntStringConverter().toJson(instance.bigInt);
-  val['bigIntMap'] = instance.bigIntMap
-      .map((k, e) => MapEntry(k, const BigIntStringConverter().toJson(e)));
-  writeNotNull(
-      'nullableBigInt',
-      _$JsonConverterToJson<String, BigInt>(
-          instance.nullableBigInt, const BigIntStringConverter().toJson));
-  val['nullableBigIntMap'] = instance.nullableBigIntMap.map((k, e) => MapEntry(
-      k,
-      _$JsonConverterToJson<String, BigInt>(
-          e, const BigIntStringConverter().toJson)));
-  writeNotNull('numberSilly',
-      TrivialNumberConverter.instance.toJson(instance.numberSilly));
-  val['numberSillySet'] = instance.numberSillySet
-      .map(TrivialNumberConverter.instance.toJson)
-      .toList();
-  writeNotNull(
-      'dateTime', const EpochDateTimeConverter().toJson(instance.dateTime));
-  writeNotNull(
-      'trivialString', trivialStringConverter.toJson(instance.trivialString));
-  writeNotNull(
-      'nullableNumberSilly',
-      _$JsonConverterToJson<int?, TrivialNumber>(instance.nullableNumberSilly,
-          TrivialNumberConverter.instance.toJson));
-  val['nullableNumberSillySet'] = instance.nullableNumberSillySet
-      .map((e) => _$JsonConverterToJson<int?, TrivialNumber>(
-          e, TrivialNumberConverter.instance.toJson))
-      .toList();
-  return val;
-}
+        JsonConverterTestClass instance) =>
+    <String, dynamic>{
+      if (const DurationMillisecondConverter().toJson(instance.duration)
+          case final value?)
+        'duration': value,
+      'durationList': instance.durationList
+          .map(const DurationMillisecondConverter().toJson)
+          .toList(),
+      'bigInt': const BigIntStringConverter().toJson(instance.bigInt),
+      'bigIntMap': instance.bigIntMap
+          .map((k, e) => MapEntry(k, const BigIntStringConverter().toJson(e))),
+      if (_$JsonConverterToJson<String, BigInt>(
+              instance.nullableBigInt, const BigIntStringConverter().toJson)
+          case final value?)
+        'nullableBigInt': value,
+      'nullableBigIntMap': instance.nullableBigIntMap.map((k, e) => MapEntry(
+          k,
+          _$JsonConverterToJson<String, BigInt>(
+              e, const BigIntStringConverter().toJson))),
+      if (TrivialNumberConverter.instance.toJson(instance.numberSilly)
+          case final value?)
+        'numberSilly': value,
+      'numberSillySet': instance.numberSillySet
+          .map(TrivialNumberConverter.instance.toJson)
+          .toList(),
+      if (const EpochDateTimeConverter().toJson(instance.dateTime)
+          case final value?)
+        'dateTime': value,
+      if (trivialStringConverter.toJson(instance.trivialString)
+          case final value?)
+        'trivialString': value,
+      if (_$JsonConverterToJson<int?, TrivialNumber>(
+              instance.nullableNumberSilly,
+              TrivialNumberConverter.instance.toJson)
+          case final value?)
+        'nullableNumberSilly': value,
+      'nullableNumberSillySet': instance.nullableNumberSillySet
+          .map((e) => _$JsonConverterToJson<int?, TrivialNumber>(
+              e, TrivialNumberConverter.instance.toJson))
+          .toList(),
+    };
 
 Value? _$JsonConverterFromJson<Json, Value>(
   Object? json,
diff --git a/json_serializable/test/src/_json_serializable_test_input.dart b/json_serializable/test/src/_json_serializable_test_input.dart
index 1458630ff..f8537f346 100644
--- a/json_serializable/test/src/_json_serializable_test_input.dart
+++ b/json_serializable/test/src/_json_serializable_test_input.dart
@@ -215,20 +215,11 @@ class NoDeserializeBadKey {
 @ShouldGenerate(
   r'''
 Map<String, dynamic> _$IncludeIfNullOverrideToJson(
-    IncludeIfNullOverride instance) {
-  final val = <String, dynamic>{
-    'number': instance.number,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('str', instance.str);
-  return val;
-}
+        IncludeIfNullOverride instance) =>
+    <String, dynamic>{
+      'number': instance.number,
+      if (instance.str case final value?) 'str': value,
+    };
 ''',
 )
 @JsonSerializable(createFactory: false, includeIfNull: false)
diff --git a/json_serializable/test/src/inheritance_test_input.dart b/json_serializable/test/src/inheritance_test_input.dart
index 875743fc7..921e442e3 100644
--- a/json_serializable/test/src/inheritance_test_input.dart
+++ b/json_serializable/test/src/inheritance_test_input.dart
@@ -8,22 +8,13 @@ SubType _$SubTypeFromJson(Map<String, dynamic> json) => SubType(
       ..superReadWriteField = (json['superReadWriteField'] as num?)?.toInt()
       ..subTypeReadWrite = (json['subTypeReadWrite'] as num).toInt();
 
-Map<String, dynamic> _$SubTypeToJson(SubType instance) {
-  final val = <String, dynamic>{
-    'super-final-field': instance.superFinalField,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('superReadWriteField', instance.superReadWriteField);
-  val['subTypeViaCtor'] = instance.subTypeViaCtor;
-  val['subTypeReadWrite'] = instance.subTypeReadWrite;
-  return val;
-}
+Map<String, dynamic> _$SubTypeToJson(SubType instance) => <String, dynamic>{
+      'super-final-field': instance.superFinalField,
+      if (instance.superReadWriteField case final value?)
+        'superReadWriteField': value,
+      'subTypeViaCtor': instance.subTypeViaCtor,
+      'subTypeReadWrite': instance.subTypeReadWrite,
+    };
 ''')
 @JsonSerializable()
 class SubType extends SuperType {
@@ -54,21 +45,13 @@ class SuperType {
 
 @ShouldGenerate(r'''
 Map<String, dynamic> _$SubTypeWithAnnotatedFieldOverrideExtendsToJson(
-    SubTypeWithAnnotatedFieldOverrideExtends instance) {
-  final val = <String, dynamic>{
-    'super-final-field': instance.superFinalField,
-  };
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('superReadWriteField', instance.superReadWriteField);
-  val['priceHalf'] = instance.priceHalf;
-  return val;
-}
+        SubTypeWithAnnotatedFieldOverrideExtends instance) =>
+    <String, dynamic>{
+      'super-final-field': instance.superFinalField,
+      if (instance.superReadWriteField case final value?)
+        'superReadWriteField': value,
+      'priceHalf': instance.priceHalf,
+    };
 ''')
 @JsonSerializable(createFactory: false)
 class SubTypeWithAnnotatedFieldOverrideExtends extends SuperType {
diff --git a/json_serializable/test/src/to_from_json_test_input.dart b/json_serializable/test/src/to_from_json_test_input.dart
index 7e5f57965..abeb24be2 100644
--- a/json_serializable/test/src/to_from_json_test_input.dart
+++ b/json_serializable/test/src/to_from_json_test_input.dart
@@ -175,18 +175,11 @@ String? _toStringNullOnEmpty(String input) => input.isEmpty ? null : input;
 @ShouldGenerate(
   r'''
 Map<String, dynamic> _$ToJsonNullableFalseIncludeIfNullFalseToJson(
-    ToJsonNullableFalseIncludeIfNullFalse instance) {
-  final val = <String, dynamic>{};
-
-  void writeNotNull(String key, dynamic value) {
-    if (value != null) {
-      val[key] = value;
-    }
-  }
-
-  writeNotNull('field', _toStringNullOnEmpty(instance.field));
-  return val;
-}
+        ToJsonNullableFalseIncludeIfNullFalse instance) =>
+    <String, dynamic>{
+      if (_toStringNullOnEmpty(instance.field) case final value?)
+        'field': value,
+    };
 ''',
 )
 @JsonSerializable(createFactory: false)