Object notifications

generator/lib/src/realm_model_info.dart

@@ -82,6 +82,10 @@ class RealmModelInfo {
             '',
           ]);
 
+      yield '@override';
+      yield 'Stream<RealmObjectChanges<$name>> get changes => RealmObject.getChanges<$name>(this);';
+      yield '';
+
       yield 'static SchemaObject get schema => _schema ??= _initSchema();';
       yield 'static SchemaObject? _schema;';
       yield 'static SchemaObject _initSchema() {';

generator/test/generator_test.dart

@@ -43,6 +43,10 @@ class _Foo {
             '  @override\n'
             '  set x(int value) => RealmObject.set(this, \'x\', value);\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Foo>> get changes =>\n'
+            '      RealmObject.getChanges<Foo>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'

generator/test/good_test.dart

@@ -43,6 +43,10 @@ class _Person {
             '  @override\n'
             '  set age(int value) => RealmObject.set(this, \'age\', value);\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Person>> get changes =>\n'
+            '      RealmObject.getChanges<Person>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'
@@ -92,6 +96,10 @@ class _Person {
             '  @override\n'
             '  set name(String value) => throw RealmUnsupportedSetError();\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Person>> get changes =>\n'
+            '      RealmObject.getChanges<Person>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'
@@ -142,6 +150,10 @@ class _Person {
             '  set children(covariant List<Person> value) =>\n'
             '      throw RealmUnsupportedSetError();\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Person>> get changes =>\n'
+            '      RealmObject.getChanges<Person>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'
@@ -191,6 +203,10 @@ class _Person {
             '  @override\n'
             '  set spouse(covariant Person? value) => RealmObject.set(this, \'spouse\', value);\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Person>> get changes =>\n'
+            '      RealmObject.getChanges<Person>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'
@@ -241,6 +257,10 @@ class _Person {
             '  @override\n'
             '  set name(String value) => RealmObject.set(this, \'name\', value);\n'
             '\n'
+            '  @override\n'
+            '  Stream<RealmObjectChanges<Person>> get changes =>\n'
+            '      RealmObject.getChanges<Person>(this);\n'
+            '\n'
             '  static SchemaObject get schema => _schema ??= _initSchema();\n'
             '  static SchemaObject? _schema;\n'
             '  static SchemaObject _initSchema() {\n'

lib/src/list.dart

@@ -175,7 +175,11 @@ class ListNotificationsController<T extends Object> extends NotificationsControl
   }
 
   @override
-  void onChanges(RealmCollectionChangesHandle changesHandle) {
+  void onChanges(Handle changesHandle) {
+    if (changesHandle is! RealmCollectionChangesHandle) {
+      throw RealmError("Invalid changes handle. RealmCollectionChangesHandle expected");
+    }
+
     final changes = RealmListChanges._(changesHandle, list);
     streamController.add(changes);
   }

lib/src/native/realm_bindings.dart

@@ -7018,6 +7018,45 @@ class RealmLibrary {
               realm_dart_on_collection_change_func_t,
               ffi.Pointer<realm_scheduler_t>)>();
 
+  /// Subscribe for notifications of changes to a realm object.
+  ///
+  /// @param realm_object The realm object to subscribe to.
+  /// @param notification_controller A handle to a Dart NotificationController instance that will be passed to the callback.
+  /// @param on_change The callback to invoke, if the realm list changes.
+  /// @return A notification token that can be released to unsubscribe.
+  ///
+  /// This is a dart specific wrapper for realm_object_add_notification_callback.
+  ffi.Pointer<realm_notification_token_t>
+      realm_dart_object_add_notification_callback(
+    ffi.Pointer<realm_object_t> list,
+    Object notification_controller,
+    realm_dart_on_object_change_func_t on_change,
+    ffi.Pointer<realm_scheduler_t> scheduler,
+  ) {
+    return _realm_dart_object_add_notification_callback(
+      list,
+      notification_controller,
+      on_change,
+      scheduler,
+    );
+  }
+
+  late final _realm_dart_object_add_notification_callbackPtr = _lookup<
+          ffi.NativeFunction<
+              ffi.Pointer<realm_notification_token_t> Function(
+                  ffi.Pointer<realm_object_t>,
+                  ffi.Handle,
+                  realm_dart_on_object_change_func_t,
+                  ffi.Pointer<realm_scheduler_t>)>>(
+      'realm_dart_object_add_notification_callback');
+  late final _realm_dart_object_add_notification_callback =
+      _realm_dart_object_add_notification_callbackPtr.asFunction<
+          ffi.Pointer<realm_notification_token_t> Function(
+              ffi.Pointer<realm_object_t>,
+              Object,
+              realm_dart_on_object_change_func_t,
+              ffi.Pointer<realm_scheduler_t>)>();
+
   ffi.Pointer<ffi.Int8> realm_dart_get_files_path() {
     return _realm_dart_get_files_path();
   }
@@ -7942,3 +7981,6 @@ typedef realm_dart_on_collection_change_func_t = ffi.Pointer<
     ffi.NativeFunction<
         ffi.Void Function(
             ffi.Handle, ffi.Pointer<realm_collection_changes_t>)>>;
+typedef realm_dart_on_object_change_func_t = ffi.Pointer<
+    ffi.NativeFunction<
+        ffi.Void Function(ffi.Handle, ffi.Pointer<realm_object_changes_t>)>>;

lib/src/native/realm_core.dart

@@ -85,7 +85,6 @@ class _RealmCore {
     });
   }
 
-  //TODO: Use Finalizers, when available, instead of native WeakHandles https://github.com/dart-lang/language/issues/1847
   SchemaHandle createSchema(List<SchemaObject> schema) {
     return using((Arena arena) {
       final classCount = schema.length;
@@ -548,6 +547,25 @@ class _RealmCore {
     }
   }
 
+  static void object_change_callback(Object object, Pointer<realm_object_changes> data) {
+    assert(object is NotificationsController, "Notification controller expected");
+
+    final controller = object as NotificationsController;
+
+    if (data == nullptr) {
+      //realm_collection_changes data clone is done in native code before this callback is invoked. nullptr data means cloning failed.
+      controller.onError(RealmError("Invalid notifications data received"));
+      return;
+    }
+
+    try {
+      final changesHandle = RealmObjectChangesHandle._(data);
+      controller.onChanges(changesHandle);
+    } catch (e) {
+      controller.onError(RealmError("Error handling collection change notifications. Error: $e"));
+    }
+  }
+
   RealmNotificationTokenHandle subscribeResultsNotifications(RealmResultsHandle handle, NotificationsController controller, SchedulerHandle schedulerHandle) {
     final onChangeCallback = Pointer.fromFunction<Void Function(ffi.Handle, Pointer<realm_collection_changes>)>(collection_change_callback);
 
@@ -560,11 +578,35 @@ class _RealmCore {
   RealmNotificationTokenHandle subscribeListNotifications(RealmListHandle handle, NotificationsController controller, SchedulerHandle schedulerHandle) {
     final onChangeCallback = Pointer.fromFunction<Void Function(ffi.Handle, Pointer<realm_collection_changes>)>(collection_change_callback);
 
-    final pointer = _realmLib.invokeGetPointer(
-        () => _realmLib.realm_dart_list_add_notification_callback(handle._pointer, controller, onChangeCallback, schedulerHandle._pointer));
+    final pointer = _realmLib
+        .invokeGetPointer(() => _realmLib.realm_dart_list_add_notification_callback(handle._pointer, controller, onChangeCallback, schedulerHandle._pointer));
+
+    return RealmNotificationTokenHandle._(pointer);
+  }
+
+  RealmNotificationTokenHandle subscribeObjectNotifications(RealmObjectHandle handle, NotificationsController controller, SchedulerHandle schedulerHandle) {
+    final onChangeCallback = Pointer.fromFunction<Void Function(ffi.Handle, Pointer<realm_object_changes>)>(object_change_callback);
+
+    final pointer = _realmLib
+        .invokeGetPointer(() => _realmLib.realm_dart_object_add_notification_callback(handle._pointer, controller, onChangeCallback, schedulerHandle._pointer));
 
     return RealmNotificationTokenHandle._(pointer);
   }
+
+  bool getObjectChangesIsDeleted(RealmObjectChangesHandle handle) {
+    return _realmLib.realm_object_changes_is_deleted(handle._pointer);
+  }
+
+  List<int> getObjectChangesProperties(RealmObjectChangesHandle handle) {
+    return using((arena) {
+      final count = _realmLib.realm_object_changes_get_num_modified_properties(handle._pointer);
+
+      final out_modified = arena<realm_property_key_t>(count);
+      _realmLib.realm_object_changes_get_modified_properties(handle._pointer, out_modified, count);
+
+      return out_modified.asTypedList(count).toList();
+    });
+  }
 }
 
 class LastError {
@@ -653,6 +695,10 @@ class RealmCollectionChangesHandle extends Handle<realm_collection_changes> {
   RealmCollectionChangesHandle._(Pointer<realm_collection_changes> pointer) : super(pointer, 256);
 }
 
+class RealmObjectChangesHandle extends Handle<realm_object_changes> {
+  RealmObjectChangesHandle._(Pointer<realm_object_changes> pointer) : super(pointer, 256);
+}
+
 extension _StringEx on String {
   Pointer<Int8> toUtf8Ptr(Allocator allocator) {
     final units = utf8.encode(this);

lib/src/realm_class.dart

@@ -34,7 +34,7 @@ export 'package:realm_common/realm_common.dart'
     show Ignored, Indexed, MapTo, PrimaryKey, RealmError, RealmModel, RealmUnsupportedSetError, RealmStateError, RealmCollectionType, RealmPropertyType;
 export "configuration.dart" show Configuration, RealmSchema, SchemaObject;
 export 'list.dart' show RealmList, RealmListOfObject, RealmListChanges;
-export 'realm_object.dart' show RealmException, RealmObject;
+export 'realm_object.dart' show RealmException, RealmObject, RealmObjectChanges;
 export 'realm_property.dart';
 export 'results.dart' show RealmResults, RealmResultsChanges;
 
@@ -267,7 +267,7 @@ class Scheduler {
 extension RealmInternal on Realm {
   RealmHandle get handle => _handle;
   Scheduler get scheduler => _scheduler;
-
+  
   RealmObject createObject(Type type, RealmObjectHandle handle) {
     RealmMetadata metadata = _getMetadata(type);
 
@@ -279,14 +279,26 @@ extension RealmInternal on Realm {
   RealmList<T> createList<T extends Object>(RealmListHandle handle) {
     return RealmListInternal.create(handle, this);
   }
+
+  List<String> getPropertyNames(Type type, List<int> propertyKeys) {
+    RealmMetadata metadata = _getMetadata(type);
+    final result = <String>[];
+    for (var key in propertyKeys) {
+      final name = metadata.getPropertyName(key);
+      if (name != null) {
+        result.add(name);
+      }
+    }
+    return result;
+  }
 }
 
 /// @nodoc
 abstract class NotificationsController {
   RealmNotificationTokenHandle? handle;
 
   RealmNotificationTokenHandle subscribe();
-  void onChanges(RealmCollectionChangesHandle changesHandle);
+  void onChanges(Handle changesHandle);
   void onError(RealmError error);
 
   void start() {