Added createJsonKeys

json_annotation/lib/src/json_serializable.dart

@@ -87,6 +87,21 @@ class JsonSerializable {
   /// such as [fieldRename].
   final bool? createFieldMap;
 
+  /// If `true` (defaults to false), a private class `_$ExampleJsonKeys`
+  /// constant is created in the generated part file.
+  ///
+  /// This class will contain every property, with the json key as value,
+  /// exposing a secured way to access the json key from the property.
+  ///
+  /// ```dart
+  /// @JsonSerializable(createJsonKeys: true)
+  /// class Example {
+  ///   // ...
+  ///   static const jsonKeys = _$PublicationImplJsonKeys();
+  /// }
+  /// ```
+  final bool? createJsonKeys;
+
   /// If `true` (defaults to false), a private, static `_$ExamplePerFieldToJson`
   /// abstract class will be generated in the part file.
   ///
@@ -247,6 +262,7 @@ class JsonSerializable {
     this.checked,
     this.constructor,
     this.createFieldMap,
+    this.createJsonKeys,
     this.createFactory,
     this.createToJson,
     this.disallowUnrecognizedKeys,

json_serializable/README.md

@@ -276,6 +276,7 @@ targets:
           constructor: ""
           create_factory: true
           create_field_map: false
+          create_json_keys: false
           create_per_field_to_json: false
           create_to_json: true
           disallow_unrecognized_keys: false

json_serializable/lib/src/encoder_helper.dart

@@ -63,6 +63,26 @@ mixin EncodeHelper implements HelperCore {
     return buffer.toString();
   }
 
+  /// Generates an object containing metadatas related to the encoding,
+  /// destined to be used by other code-generators.
+  String createJsonKeys(Set<FieldElement> accessibleFieldSet) {
+    assert(config.createJsonKeys);
+
+    final buffer = StringBuffer(
+      'class _\$${element.name.nonPrivate}JsonKeys {',
+    )..write('const _\$${element.name.nonPrivate}JsonKeys();');
+
+    for (final field in accessibleFieldSet) {
+      buffer.writeln(
+        'final String ${field.name} = ${escapeDartString(nameAccess(field))};',
+      );
+    }
+
+    buffer.write('}');
+
+    return buffer.toString();
+  }
+
   Iterable<String> createToJson(Set<FieldElement> accessibleFields) sync* {
     assert(config.createToJson);
 

json_serializable/lib/src/generator_helper.dart

@@ -132,6 +132,10 @@ class GeneratorHelper extends HelperCore with EncodeHelper, DecodeHelper {
       yield createFieldMap(accessibleFieldSet);
     }
 
+    if (config.createJsonKeys) {
+      yield createJsonKeys(accessibleFieldSet);
+    }
+
     if (config.createPerFieldToJson) {
       yield createPerFieldToJson(accessibleFieldSet);
     }

json_serializable/lib/src/type_helpers/config_types.dart

@@ -49,6 +49,7 @@ class ClassConfig {
   final bool createFactory;
   final bool createToJson;
   final bool createFieldMap;
+  final bool createJsonKeys;
   final bool createPerFieldToJson;
   final bool disallowUnrecognizedKeys;
   final bool explicitToJson;
@@ -66,6 +67,7 @@ class ClassConfig {
     required this.createFactory,
     required this.createToJson,
     required this.createFieldMap,
+    required this.createJsonKeys,
     required this.createPerFieldToJson,
     required this.disallowUnrecognizedKeys,
     required this.explicitToJson,
@@ -85,6 +87,8 @@ class ClassConfig {
         constructor: config.constructor ?? ClassConfig.defaults.constructor,
         createFieldMap:
             config.createFieldMap ?? ClassConfig.defaults.createFieldMap,
+        createJsonKeys:
+            config.createJsonKeys ?? ClassConfig.defaults.createJsonKeys,
         createPerFieldToJson: config.createPerFieldToJson ??
             ClassConfig.defaults.createPerFieldToJson,
         createFactory:
@@ -113,6 +117,7 @@ class ClassConfig {
     createFactory: true,
     createToJson: true,
     createFieldMap: false,
+    createJsonKeys: false,
     createPerFieldToJson: false,
     disallowUnrecognizedKeys: false,
     explicitToJson: false,
@@ -129,6 +134,7 @@ class ClassConfig {
         createFactory: createFactory,
         createToJson: createToJson,
         createFieldMap: createFieldMap,
+        createJsonKeys: createJsonKeys,
         createPerFieldToJson: createPerFieldToJson,
         ignoreUnannotated: ignoreUnannotated,
         explicitToJson: explicitToJson,

json_serializable/lib/src/utils.dart

@@ -58,6 +58,7 @@ JsonSerializable _valueForAnnotation(ConstantReader reader) => JsonSerializable(
       createFactory: reader.read('createFactory').literalValue as bool?,
       createToJson: reader.read('createToJson').literalValue as bool?,
       createFieldMap: reader.read('createFieldMap').literalValue as bool?,
+      createJsonKeys: reader.read('createJsonKeys').literalValue as bool?,
       createPerFieldToJson:
           reader.read('createPerFieldToJson').literalValue as bool?,
       disallowUnrecognizedKeys:
@@ -106,6 +107,7 @@ ClassConfig mergeConfig(
     createFactory: annotation.createFactory ?? config.createFactory,
     createToJson: annotation.createToJson ?? config.createToJson,
     createFieldMap: annotation.createFieldMap ?? config.createFieldMap,
+    createJsonKeys: annotation.createJsonKeys ?? config.createJsonKeys,
     createPerFieldToJson:
         annotation.createPerFieldToJson ?? config.createPerFieldToJson,
     disallowUnrecognizedKeys:

json_serializable/test/config_test.dart

@@ -153,6 +153,7 @@ const _invalidConfig = {
   'constructor': 42,
   'create_factory': 42,
   'create_field_map': 42,
+  'create_json_keys': 42,
   'create_per_field_to_json': 42,
   'create_to_json': 42,
   'disallow_unrecognized_keys': 42,

json_serializable/test/integration/integration_test.dart

@@ -10,6 +10,7 @@ import 'converter_examples.dart';
 import 'create_per_field_to_json_example.dart';
 import 'field_map_example.dart';
 import 'json_enum_example.dart';
+import 'json_keys_example.dart' as js_keys;
 import 'json_test_common.dart' show Category, Platform, StatusCode;
 import 'json_test_example.dart';
 
@@ -471,4 +472,14 @@ void main() {
   test('value field index fun', () {
     expect(enumValueFieldIndexValues, [0, 701, 2]);
   });
+
+  test(r'_$ModelJsonKeys', () {
+    expect(js_keys.Model.jsonKeys.firstName, 'first-name');
+    expect(js_keys.Model.jsonKeys.lastName, 'LAST_NAME');
+  });
+
+  test(r'Generates _$PrivateModelJsonKeys instead of __$PrivateModelJsonKeys',
+      () {
+    expect(js_keys.privateModelJsonKeys.fullName, 'full-name');
+  });
 }

json_serializable/test/integration/json_keys_example.dart

@@ -0,0 +1,45 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'json_keys_example.g.dart';
+
+@JsonSerializable(createJsonKeys: true, fieldRename: FieldRename.kebab)
+class Model {
+  Model({
+    required this.firstName,
+    required this.lastName,
+    this.ignoredName,
+  });
+
+  factory Model.fromJson(Map<String, Object?> json) => _$ModelFromJson(json);
+
+  final String firstName;
+
+  @JsonKey(name: 'LAST_NAME')
+  final String lastName;
+
+  @JsonKey(includeFromJson: false, includeToJson: false)
+  final String? ignoredName;
+
+  String get fullName => '$firstName $lastName';
+
+  Map<String, Object?> toJson() => _$ModelToJson(this);
+
+  static const jsonKeys = _$ModelJsonKeys();
+}
+
+@JsonSerializable(
+  createJsonKeys: true,
+  fieldRename: FieldRename.kebab,
+  createFactory: false,
+)
+class _PrivateModel {
+  _PrivateModel(this.fullName);
+
+  final String fullName;
+
+  Map<String, Object?> toJson() => _$PrivateModelToJson(this);
+
+  static const jsonKeys = _$PrivateModelJsonKeys();
+}
+
+const privateModelJsonKeys = _PrivateModel.jsonKeys;

json_serializable/test/shared_config.dart

@@ -20,6 +20,7 @@ final generatorConfigNonDefaultJson =
   createFactory: false,
   createToJson: false,
   createFieldMap: true,
+  createJsonKeys: true,
   createPerFieldToJson: true,
   disallowUnrecognizedKeys: true,
   explicitToJson: true,

json_serializable/test/test_sources/test_sources.dart

@@ -16,6 +16,7 @@ class ConfigurationImplicitDefaults {
   createFactory: true,
   createToJson: true,
   createFieldMap: false,
+  createJsonKeys: false,
   createPerFieldToJson: false,
   disallowUnrecognizedKeys: false,
   explicitToJson: false,

json_serializable/tool/readme/readme_template.md

@@ -141,6 +141,7 @@ targets:
           constructor: ""
           create_factory: true
           create_field_map: false
+          create_json_keys: false
           create_per_field_to_json: false
           create_to_json: true
           disallow_unrecognized_keys: false