RDART-910: Add support for RealmObject.objectSchema

CHANGELOG.md

@@ -43,6 +43,7 @@
     Realm.shutdown();
   }
   ```
+* Removed `SchemaObject.properties` - instead, `SchemaObject` is now an iterable collection of `Property`. (Issue [#1449](https://github.com/realm/realm-dart/issues/1449))
 
 ### Enhancements
 * Realm objects can now be serialized as [EJSON](https://www.mongodb.com/docs/manual/reference/mongodb-extended-json/)
@@ -103,6 +104,8 @@
   ```
 * Added `RealmValueType` enum that contains all the possible types that can be wrapped by a `RealmValue`. (PR [#1469](https://github.com/realm/realm-dart/pull/1469))
 * Added support for accessing `Set` and `Map` types using the dynamic object API - `obj.dynamic.getSet/getMap`. (PR [#1533](https://github.com/realm/realm-dart/pull/1533))
+* Added `RealmObjectBase.objectSchema` that returns the schema for this object. In most cases, this would be the schema defined in the model, but in case the Realm is opened as dynamic (by providing an empty collection for schemaObjects in the config) or using `FlexibleSyncConfiguration`, it may change as the schema on disk changes. (Issue [#1449](https://github.com/realm/realm-dart/issues/1449))
+* Added `Realm.schemaChanges` that returns a stream of schema changes that can be listened to. Only dynamic and synchronized Realms will emit schema changes. (Issue [#1449](https://github.com/realm/realm-dart/issues/1449))
 
 
 ### Fixed

packages/realm_dart/lib/src/configuration.dart

@@ -398,21 +398,31 @@ class InMemoryConfiguration extends Configuration {
 /// A collection of properties describing the underlying schema of a [RealmObjectBase].
 ///
 /// {@category Configuration}
-class SchemaObject {
+class SchemaObject extends Iterable<SchemaProperty> {
+  final List<SchemaProperty> _properties;
+
   /// Schema object type.
   final Type type;
 
-  /// Collection of the properties of this schema object.
-  final List<SchemaProperty> properties;
-
   /// Returns the name of this schema type.
   final String name;
 
   /// Returns the base type of this schema object.
   final ObjectType baseType;
 
   /// Creates schema instance with object type and collection of object's properties.
-  const SchemaObject(this.baseType, this.type, this.name, this.properties);
+  SchemaObject(this.baseType, this.type, this.name, Iterable<SchemaProperty> properties) : _properties = List.from(properties);
+
+  @override
+  Iterator<SchemaProperty> get iterator => _properties.iterator;
+
+  @override
+  int get length => _properties.length;
+
+  SchemaProperty operator [](int index) => _properties[index];
+
+  @override
+  SchemaProperty elementAt(int index) => _properties.elementAt(index);
 }
 
 /// Describes the complete set of classes which may be stored in a `Realm`
@@ -441,6 +451,14 @@ class RealmSchema extends Iterable<SchemaObject> {
 /// @nodoc
 extension SchemaObjectInternal on SchemaObject {
   bool get isGenericRealmObject => type == RealmObject || type == EmbeddedObject || type == RealmObjectBase;
+
+  void add(SchemaProperty property) => _properties.add(property);
+}
+
+extension RealmSchemaInternal on RealmSchema {
+  void add(SchemaObject obj) {
+    _schema.add(obj);
+  }
 }
 
 /// [ClientResetHandler] is triggered if the device and server cannot agree

packages/realm_dart/lib/src/native/realm_core.dart

@@ -161,8 +161,8 @@ class _RealmCore {
       for (var i = 0; i < classCount; i++) {
         final schemaObject = schema.elementAt(i);
         final classInfo = schemaClasses.elementAt(i).ref;
-        final propertiesCount = schemaObject.properties.length;
-        final computedCount = schemaObject.properties.where((p) => p.isComputed).length;
+        final propertiesCount = schemaObject.length;
+        final computedCount = schemaObject.where((p) => p.isComputed).length;
         final persistedCount = propertiesCount - computedCount;
 
         classInfo.name = schemaObject.name.toCharPtr(arena);
@@ -175,7 +175,7 @@ class _RealmCore {
         final properties = arena<realm_property_info_t>(propertiesCount);
 
         for (var j = 0; j < propertiesCount; j++) {
-          final schemaProperty = schemaObject.properties[j];
+          final schemaProperty = schemaObject[j];
           final propInfo = properties.elementAt(j).ref;
           propInfo.name = schemaProperty.mapTo.toCharPtr(arena);
           propInfo.public_name = (schemaProperty.mapTo != schemaProperty.name ? schemaProperty.name : '').toCharPtr(arena);
@@ -275,7 +275,7 @@ class _RealmCore {
       } else if (config is InMemoryConfiguration) {
         _realmLib.realm_config_set_in_memory(configHandle._pointer, true);
       } else if (config is FlexibleSyncConfiguration) {
-        _realmLib.realm_config_set_schema_mode(configHandle._pointer, realm_schema_mode.RLM_SCHEMA_MODE_ADDITIVE_EXPLICIT);
+        _realmLib.realm_config_set_schema_mode(configHandle._pointer, realm_schema_mode.RLM_SCHEMA_MODE_ADDITIVE_DISCOVERED);
         final syncConfigPtr = _realmLib.invokeGetPointer(() => _realmLib.realm_flx_sync_config_new(config.user.handle._pointer));
         try {
           _realmLib.realm_sync_config_set_session_stop_policy(syncConfigPtr, config.sessionStopPolicy.index);
@@ -321,9 +321,16 @@ class _RealmCore {
         _realmLib.realm_config_set_schema_mode(configHandle._pointer, realm_schema_mode.RLM_SCHEMA_MODE_ADDITIVE_EXPLICIT);
         _realmLib.realm_config_set_force_sync_history(configPtr, true);
       }
+
       if (config.encryptionKey != null) {
         _realmLib.realm_config_set_encryption_key(configPtr, config.encryptionKey!.toUint8Ptr(arena), encryptionKeySize);
       }
+
+      // For sync and for dynamic Realms, we need to have a complete view of the schema in Core.
+      if (config.schemaObjects.isEmpty || config is FlexibleSyncConfiguration) {
+        _realmLib.realm_config_set_schema_subset_mode(configHandle._pointer, realm_schema_subset_mode.RLM_SCHEMA_SUBSET_MODE_COMPLETE);
+      }
+
       return configHandle;
     });
   }
@@ -948,38 +955,42 @@ class _RealmCore {
       }
 
       final primaryKey = classInfo.ref.primary_key.cast<Utf8>().toRealmDartString(treatEmptyAsNull: true);
-      return RealmObjectMetadata(schema, classInfo.ref.key, _getPropertyMetadata(realm, classInfo.ref.key, primaryKey));
+      return RealmObjectMetadata(schema, classInfo.ref.key, _getPropertiesMetadata(realm, classInfo.ref.key, primaryKey, arena));
     });
   }
 
-  Map<String, RealmPropertyMetadata> _getPropertyMetadata(Realm realm, int classKey, String? primaryKeyName) {
+  Map<String, RealmPropertyMetadata> getPropertiesMetadata(Realm realm, int classKey, String? primaryKeyName) {
     return using((Arena arena) {
-      final propertyCountPtr = arena<Size>();
-      _realmLib.invokeGetBool(
-          () => _realmLib.realm_get_property_keys(realm.handle._pointer, classKey, nullptr, 0, propertyCountPtr), "Error getting property count");
-
-      var propertyCount = propertyCountPtr.value;
-      final propertiesPtr = arena<realm_property_info_t>(propertyCount);
-      _realmLib.invokeGetBool(() => _realmLib.realm_get_class_properties(realm.handle._pointer, classKey, propertiesPtr, propertyCount, propertyCountPtr),
-          "Error getting class properties.");
-
-      propertyCount = propertyCountPtr.value;
-      Map<String, RealmPropertyMetadata> result = <String, RealmPropertyMetadata>{};
-      for (var i = 0; i < propertyCount; i++) {
-        final property = propertiesPtr.elementAt(i);
-        final propertyName = property.ref.name.cast<Utf8>().toRealmDartString()!;
-        final objectType = property.ref.link_target.cast<Utf8>().toRealmDartString(treatEmptyAsNull: true);
-        final linkOriginProperty = property.ref.link_origin_property_name.cast<Utf8>().toRealmDartString(treatEmptyAsNull: true);
-        final isNullable = property.ref.flags & realm_property_flags.RLM_PROPERTY_NULLABLE != 0;
-        final isPrimaryKey = propertyName == primaryKeyName;
-        final propertyMeta = RealmPropertyMetadata(property.ref.key, objectType, linkOriginProperty, RealmPropertyType.values.elementAt(property.ref.type),
-            isNullable, isPrimaryKey, RealmCollectionType.values.elementAt(property.ref.collection_type));
-        result[propertyName] = propertyMeta;
-      }
-      return result;
+      return _getPropertiesMetadata(realm, classKey, primaryKeyName, arena);
     });
   }
 
+  Map<String, RealmPropertyMetadata> _getPropertiesMetadata(Realm realm, int classKey, String? primaryKeyName, Arena arena) {
+    final propertyCountPtr = arena<Size>();
+    _realmLib.invokeGetBool(
+        () => _realmLib.realm_get_property_keys(realm.handle._pointer, classKey, nullptr, 0, propertyCountPtr), "Error getting property count");
+
+    var propertyCount = propertyCountPtr.value;
+    final propertiesPtr = arena<realm_property_info_t>(propertyCount);
+    _realmLib.invokeGetBool(() => _realmLib.realm_get_class_properties(realm.handle._pointer, classKey, propertiesPtr, propertyCount, propertyCountPtr),
+        "Error getting class properties.");
+
+    propertyCount = propertyCountPtr.value;
+    Map<String, RealmPropertyMetadata> result = <String, RealmPropertyMetadata>{};
+    for (var i = 0; i < propertyCount; i++) {
+      final property = propertiesPtr.elementAt(i);
+      final propertyName = property.ref.name.cast<Utf8>().toRealmDartString()!;
+      final objectType = property.ref.link_target.cast<Utf8>().toRealmDartString(treatEmptyAsNull: true);
+      final linkOriginProperty = property.ref.link_origin_property_name.cast<Utf8>().toRealmDartString(treatEmptyAsNull: true);
+      final isNullable = property.ref.flags & realm_property_flags.RLM_PROPERTY_NULLABLE != 0;
+      final isPrimaryKey = propertyName == primaryKeyName;
+      final propertyMeta = RealmPropertyMetadata(property.ref.key, objectType, linkOriginProperty, RealmPropertyType.values.elementAt(property.ref.type),
+          isNullable, isPrimaryKey, RealmCollectionType.values.elementAt(property.ref.collection_type));
+      result[propertyName] = propertyMeta;
+    }
+    return result;
+  }
+
   RealmObjectHandle createRealmObject(Realm realm, int classKey) {
     final realmPtr = _realmLib.invokeGetPointer(() => _realmLib.realm_object_create(realm.handle._pointer, classKey));
     return RealmObjectHandle._(realmPtr, realm.handle);
@@ -1757,6 +1768,15 @@ class _RealmCore {
     controller.onUserChanged();
   }
 
+  static void schema_change_callback(Pointer<Void> userdata, Pointer<realm_schema> data) {
+    final Realm realm = userdata.toObject();
+    try {
+      realm.updateSchema();
+    } catch (e) {
+      Realm.logger.log(RealmLogLevel.error, 'Failed to update Realm schema: $e');
+    }
+  }
+
   RealmNotificationTokenHandle subscribeResultsNotifications(RealmResults results, NotificationsController controller) {
     final pointer = _realmLib.invokeGetPointer(() => _realmLib.realm_results_add_notification_callback(
           results.handle._pointer,
@@ -1817,6 +1837,13 @@ class _RealmCore {
     return UserNotificationTokenHandle._(notification_token);
   }
 
+  RealmCallbackTokenHandle subscribeForSchemaNotifications(Realm realm) {
+    final pointer = _realmLib.invokeGetPointer(() => _realmLib.realm_add_schema_changed_callback(realm.handle._pointer,
+        Pointer.fromFunction(schema_change_callback), realm.toPersistentHandle(), _realmLib.addresses.realm_dart_delete_persistent_handle));
+
+    return RealmCallbackTokenHandle._(pointer, realm.handle);
+  }
+
   bool getObjectChangesIsDeleted(RealmObjectChangesHandle handle) {
     return _realmLib.realm_object_changes_is_deleted(handle._pointer);
   }
@@ -3248,6 +3275,10 @@ class _RealmQueryHandle extends RootedHandleBase<realm_query> {
   _RealmQueryHandle._(Pointer<realm_query> pointer, RealmHandle root) : super(root, pointer, 256);
 }
 
+class RealmCallbackTokenHandle extends RootedHandleBase<realm_callback_token> {
+  RealmCallbackTokenHandle._(Pointer<realm_callback_token> pointer, RealmHandle root) : super(root, pointer, 32);
+}
+
 class RealmNotificationTokenHandle extends RootedHandleBase<realm_notification_token> {
   RealmNotificationTokenHandle._(Pointer<realm_notification_token> pointer, RealmHandle root) : super(root, pointer, 32);
 }