(WIP) Move results of objects specific functionality to extension method

.vscode/settings.json

@@ -8,6 +8,7 @@
   "dart.lineLength": 160,
   "cSpell.words": [
     "apikeys",
+    "BEGINSWITH",
     "bson",
     "deallocated",
     "deleter",

lib/src/list.dart

@@ -40,6 +40,8 @@ abstract class RealmList<T extends Object?> with RealmEntityMixin implements Lis
   /// and it's parent object hasn't been deleted.
   bool get isValid;
 
+  RealmResults<T> get asResults;
+
   factory RealmList._(RealmListHandle handle, Realm realm, RealmObjectMetadata? metadata) => ManagedRealmList._(handle, realm, metadata);
   factory RealmList(Iterable<T> items) => UnmanagedRealmList(items);
 }
@@ -126,6 +128,9 @@ class ManagedRealmList<T extends Object?> extends collection.ListBase<T> with Re
 
   @override
   bool get isValid => realmCore.listIsValid(this);
+
+  @override
+  RealmResults<T> get asResults => RealmResultsInternal.createFromList(handle, realm, _metadata);
 }
 
 class UnmanagedRealmList<T extends Object?> extends collection.ListBase<T> with RealmEntityMixin implements RealmList<T> {
@@ -160,6 +165,9 @@ class UnmanagedRealmList<T extends Object?> extends collection.ListBase<T> with
 
   @override
   bool get isValid => true;
+
+  @override
+  RealmResults<T> get asResults => throw RealmException("Unmanaged lists cannot be converted to results");
 }
 
 // The query operations on lists, as well as the ability to subscribe for notifications,
@@ -173,15 +181,13 @@ extension RealmListOfObject<T extends RealmObject> on RealmList<T> {
   /// The Realm Dart and Realm Flutter SDKs supports querying based on a language inspired by [NSPredicate](https://academy.realm.io/posts/nspredicate-cheatsheet/)
   /// and [Predicate Programming Guide.](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Predicates/AdditionalChapters/Introduction.html#//apple_ref/doc/uid/TP40001789)
   RealmResults<T> query(String query, [List<Object> arguments = const []]) {
-    final managedList = asManaged();
-    final handle = realmCore.queryList(managedList, query, arguments);
+    final handle = realmCore.queryList(asManaged, query, arguments);
     return RealmResultsInternal.create<T>(handle, realm, _metadata);
   }
 
   /// Allows listening for changes when the contents of this collection changes.
   Stream<RealmListChanges<T>> get changes {
-    final managedList = asManaged();
-    final controller = ListNotificationsController<T>(managedList);
+    final controller = ListNotificationsController<T>(asManaged);
     return controller.createStream();
   }
 }
@@ -197,9 +203,9 @@ extension RealmListInternal<T extends Object?> on RealmList<T> {
     }
   }
 
-  ManagedRealmList<T> asManaged() => this is ManagedRealmList<T> ? this as ManagedRealmList<T> : throw RealmStateError('$this is not managed');
+  ManagedRealmList<T> get asManaged => this is ManagedRealmList<T> ? this as ManagedRealmList<T> : throw RealmStateError('$this is not managed');
 
-  RealmListHandle get handle => asManaged()._handle;
+  RealmListHandle get handle => asManaged._handle;
 
   static RealmList<T> create<T extends Object?>(RealmListHandle handle, Realm realm, RealmObjectMetadata? metadata) => RealmList<T>._(handle, realm, metadata);
 

lib/src/native/realm_core.dart

@@ -735,6 +735,10 @@ class _RealmCore {
     });
   }
 
+  RealmResultsHandle resultsFromList(RealmListHandle listHandle) {
+    return RealmResultsHandle._(listHandle._pointer.cast<realm_results>());
+  }
+
   RealmObjectHandle getObjectAt(RealmResults results, int index) {
     final pointer = _realmLib.invokeGetPointer(() => _realmLib.realm_results_get_object(results.handle._pointer, index));
     return RealmObjectHandle._(pointer);

lib/src/realm_class.dart

@@ -76,7 +76,7 @@ export 'credentials.dart' show Credentials, AuthProviderType, EmailPasswordAuthP
 export 'list.dart' show RealmList, RealmListOfObject, RealmListChanges;
 export 'realm_object.dart' show RealmEntityMixin, RealmObjectMixin, RealmException, RealmObject, RealmObjectChanges, DynamicRealmObject;
 export 'realm_property.dart';
-export 'results.dart' show RealmResults, RealmResultsChanges;
+export 'results.dart' show RealmResults, RealmResultsChanges, RealmResultsOfObject;
 export 'session.dart' show Session, SessionState, ConnectionState, ProgressDirection, ProgressMode, SyncProgress, ConnectionStateChange;
 export 'subscription.dart' show Subscription, SubscriptionSet, SubscriptionSetState, MutableSubscriptionSet;
 export 'user.dart' show User, UserState, UserIdentity;

lib/src/results.dart

@@ -20,6 +20,8 @@ import 'dart:async';
 import 'dart:collection' as collection;
 import 'dart:ffi';
 
+import 'package:realm_dart/src/type_utils.dart';
+
 import 'collections.dart';
 import 'native/realm_core.dart';
 import 'realm_class.dart';
@@ -36,7 +38,7 @@ class RealmResults<T extends Object?> extends collection.IterableBase<T> impleme
   /// The Realm instance this collection belongs to.
   final Realm realm;
 
-  final _supportsSnapshot = <T>[] is List<RealmObject?>;
+  final _supportsSnapshot = isSubtype<T, RealmObject>();
 
   RealmResults._(this._handle, this.realm, this._metadata);
 
@@ -46,15 +48,6 @@ class RealmResults<T extends Object?> extends collection.IterableBase<T> impleme
     return RealmObjectInternal.create<T>(realm, handle, _metadata!);
   }
 
-  /// Returns a new [RealmResults] filtered according to the provided query.
-  ///
-  /// The Realm Dart and Realm Flutter SDKs supports querying based on a language inspired by [NSPredicate](https://academy.realm.io/posts/nspredicate-cheatsheet/)
-  /// and [Predicate Programming Guide.](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Predicates/AdditionalChapters/Introduction.html#//apple_ref/doc/uid/TP40001789)
-  RealmResults<T> query(String query, [List<Object> args = const []]) {
-    final handle = realmCore.queryResults(this, query, args);
-    return RealmResultsInternal.create<T>(handle, realm, _metadata);
-  }
-
   /// `true` if the `Results` collection is empty.
   @override
   bool get isEmpty => length == 0;
@@ -73,6 +66,25 @@ class RealmResults<T extends Object?> extends collection.IterableBase<T> impleme
   /// The number of values in this `Results` collection.
   @override
   int get length => realmCore.getResultsCount(this);
+}
+
+// The query operations on results, as well as the ability to subscribe for notifications,
+// only work for results of objects (core restriction), so we add these as an extension methods
+// to allow the compiler to prevent misuse.
+extension RealmResultsOfObject<T extends RealmObject> on RealmResults<T> {
+  RealmResults<T> snapshot() {
+    final handle = realmCore.resultsSnapshot(this);
+    return RealmResults<T>._(handle, realm, _metadata);
+  }
+
+  /// Returns a new [RealmResults] filtered according to the provided query.
+  ///
+  /// The Realm Dart and Realm Flutter SDKs supports querying based on a language inspired by [NSPredicate](https://academy.realm.io/posts/nspredicate-cheatsheet/)
+  /// and [Predicate Programming Guide.](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Predicates/AdditionalChapters/Introduction.html#//apple_ref/doc/uid/TP40001789)
+  RealmResults<T> query(String query, [List<Object> args = const []]) {
+    final handle = realmCore.queryResults(this, query, args);
+    return RealmResultsInternal.create<T>(handle, realm, _metadata);
+  }
 
   /// Allows listening for changes when the contents of this collection changes.
   Stream<RealmResultsChanges<T>> get changes {
@@ -91,9 +103,19 @@ extension RealmResultsInternal on RealmResults {
 
   RealmResultsHandle get handle => _handle;
 
-  static RealmResults<T> create<T extends Object?>(RealmResultsHandle handle, Realm realm, RealmObjectMetadata? metadata) {
-    return RealmResults<T>._(handle, realm, metadata);
-  }
+  static RealmResults<T> create<T extends Object?>(
+    RealmResultsHandle handle,
+    Realm realm,
+    RealmObjectMetadata? metadata,
+  ) =>
+      RealmResults<T>._(handle, realm, metadata);
+
+  static RealmResults<T> createFromList<T extends Object?>(
+    RealmListHandle handle,
+    Realm realm,
+    RealmObjectMetadata? metadata,
+  ) =>
+      RealmResults<T>._(realmCore.resultsFromList(handle), realm, metadata);
 }
 
 /// Describes the changes in a Realm results collection since the last time the notification callback was invoked.

test/subscription_test.dart

@@ -295,18 +295,18 @@ Future<void> main([List<String>? args]) async {
 
     ObjectId newOid() => ObjectId.fromBytes(randomBytes(12));
 
-    final oids = <ObjectId>{};
+    final objectIds = <ObjectId>{};
     const max = 1000;
     subscriptions.update((mutableSubscriptions) {
-      oids.addAll([
+      objectIds.addAll([
         for (int i = 0; i < max; ++i) mutableSubscriptions.add(realm.query<Task>(r'_id == $0', [newOid()])).id
       ]);
     });
-    expect(oids.length, max); // no collisions
+    expect(objectIds.length, max); // no collisions
     expect(subscriptions.length, max);
 
     for (final sub in subscriptions) {
-      expect(sub.id, isIn(oids));
+      expect(sub.id, isIn(objectIds));
     }
   });
 
@@ -499,7 +499,7 @@ Future<void> main([List<String>? args]) async {
     expect(() => realm.write(() => realm.add(Task(ObjectId()))), throws<RealmException>("no flexible sync subscription has been created"));
   });
 
-  testSubscriptions('Subscription on unqueryable field sould throw', (realm) async {
+  testSubscriptions('Subscription on non-queryable field should throw', (realm) async {
     realm.subscriptions.update((mutableSubscriptions) {
       mutableSubscriptions.add(realm.all<Event>());
     });
@@ -513,7 +513,7 @@ Future<void> main([List<String>? args]) async {
           isCompleted: false,
           durationInMinutes: 10,
         ),
-        Event(ObjectId(), name: "Some other eveent", isCompleted: true, durationInMinutes: 60),
+        Event(ObjectId(), name: "Some other event", isCompleted: true, durationInMinutes: 60),
       ]);
     });
 
@@ -550,7 +550,7 @@ Future<void> main([List<String>? args]) async {
       realm.addAll([
         Event(ObjectId(), name: "NPMG Event", isCompleted: true, durationInMinutes: 30),
         Event(ObjectId(), name: "NPMG Meeting", isCompleted: false, durationInMinutes: 10),
-        Event(ObjectId(), name: "Some other eveent", isCompleted: true, durationInMinutes: 60),
+        Event(ObjectId(), name: "Some other event", isCompleted: true, durationInMinutes: 60),
       ]);
     });