Avoid unnecessary observable notifications of Iterable or Map fields

mobx/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.2.3
+
+- Avoid unnecessary observable notifications of `@observable` `Iterable` or `Map` fields of Stores by [@amondnet](https://github.com/amondnet) in [#951](https://github.com/mobxjs/mobx.dart/pull/951)
+
 ## 2.2.2
 
 - Fix [#956]((https://github.com/mobxjs/mobx.dart/issues/956)): ObservableSet` and `ObservableMap` should not notify all listeners when `observe` with fireImmediately. by [@amondnet](https://github.com/amondnet) in [#962](https://github.com/mobxjs/mobx.dart/pull/962)

mobx/lib/src/core/atom_extensions.dart

@@ -1,5 +1,7 @@
 import 'package:mobx/mobx.dart';
 
+import '../utils.dart';
+
 extension AtomSpyReporter on Atom {
  void reportRead() {
  context.enforceReadPolicy(this);
@@ -8,11 +10,10 @@ extension AtomSpyReporter on Atom {
 
  void reportWrite<T>(T newValue, T oldValue, void Function() setNewValue,
  {EqualityComparer<T>? equals}) {
- final areEqual =
- equals == null ? oldValue == newValue : equals(oldValue, newValue);
+ final areEqual = equals ?? equatable;
 
  // Avoid unnecessary observable notifications of @observable fields of Stores
- if (areEqual) {
+ if (areEqual(newValue, oldValue)) {
  return;
  }
 

mobx/lib/src/core/observable.dart

@@ -105,7 +105,7 @@ class Observable<T> extends Atom
  }
 
  final areEqual =
- equals == null ? prepared == value : equals!(prepared, _value);
+ equals == null ? equatable(prepared, value) : equals!(prepared, _value);
 
  return (!areEqual) ? prepared : WillChangeNotification.unchanged;
  }

mobx/lib/src/utils.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart' show DeepCollectionEquality;
+
 const Duration ms = Duration(milliseconds: 1);
 
 Timer Function(void Function()) createDelayedScheduler(int delayMs) =>
@@ -20,3 +22,19 @@ mixin DebugCreationStack {
  return result;
  }();
 }
+
+/// Determines whether [a] and [b] are equal.
+bool equatable<T>(T a, T b) {
+ if (identical(a, b)) return true;
+ if (a is Iterable || a is Map) {
+ if (!_equality.equals(a, b)) return false;
+ } else if (a.runtimeType != b.runtimeType) {
+ return false;
+ } else if (a != b) {
+ return false;
+ }
+
+ return true;
+}
+
+const DeepCollectionEquality _equality = DeepCollectionEquality();

mobx/lib/version.dart

@@ -1,4 +1,4 @@
 // Generated via set_version.dart. !!!DO NOT MODIFY BY HAND!!!
 
 /// The current version as per `pubspec.yaml`.
-const version = '2.2.2';
+const version = '2.2.3';

mobx/pubspec.yaml

@@ -1,5 +1,5 @@
 name: mobx
-version: 2.2.2
+version: 2.2.3
 description: "MobX is a library for reactively managing the state of your applications. Use the power of observables, actions, and reactions to supercharge your Dart and Flutter apps."
 
 homepage: https://github.com/mobxjs/mobx.dart
@@ -10,10 +10,10 @@ environment:
 
 dependencies:
  meta: ^1.3.0
+ collection: ^1.15.0
 
 dev_dependencies:
  build_runner: ^2.0.6
- collection: ^1.15.0
  coverage: ^1.0.1
  fake_async: ^1.2.0
  lints: ^2.0.0

mobx/test/atom_extensions_test.dart

@@ -4,75 +4,123 @@ import 'package:test/test.dart';
 void main() {
  test(
  'when write to @observable field with changed value, should trigger notifications for downstream',
- () {
- final store = _ExampleStore();
+  () {
+  final store = _ExampleStore();
 
- final autorunResults = <String>[];
- autorun((_) => autorunResults.add(store.value));
+  final autorunResults = <String>[];
+  autorun((_) => autorunResults.add(store.value));
 
- expect(autorunResults, ['first']);
+  expect(autorunResults, ['first']);
 
- store.value = 'second';
+  store.value = 'second';
 
- expect(autorunResults, ['first', 'second']);
- });
+  expect(autorunResults, ['first', 'second']);
+  });
 
  // fixed by #855
  test(
  'when write to @observable field with unchanged value, should not trigger notifications for downstream',
- () {
- final store = _ExampleStore();
+  () {
+  final store = _ExampleStore();
 
- final autorunResults = <String>[];
- autorun((_) => autorunResults.add(store.value));
+  final autorunResults = <String>[];
+  autorun((_) => autorunResults.add(store.value));
 
- expect(autorunResults, ['first']);
+  expect(autorunResults, ['first']);
 
- store.value = store.value;
+  store.value = store.value;
 
- expect(autorunResults, ['first']);
- });
+  expect(autorunResults, ['first']);
+  });
 
  test(
  'when write to @alwaysNotify field with unchanged value, should trigger notifications for downstream',
- () {
- final store = _ExampleStore();
+  () {
+  final store = _ExampleStore();
 
- final autorunResults = <String>[];
- autorun((_) => autorunResults.add(store.value2));
+  final autorunResults = <String>[];
+  autorun((_) => autorunResults.add(store.value2));
 
- expect(autorunResults, ['first']);
+  expect(autorunResults, ['first']);
 
- store.value2 = store.value2;
+  store.value2 = store.value2;
 
- expect(autorunResults, ['first', 'first']);
- });
+  expect(autorunResults, ['first', 'first']);
+  });
 
  test(
  'when write to @MakeObservable(equals: "a?.length == b?.length") field with changed value and not equals, should trigger notifications for downstream',
- () {
- final store = _ExampleStore();
+  () {
+  final store = _ExampleStore();
 
- final autorunResults = <String>[];
- autorun((_) => autorunResults.add(store.value3));
+  final autorunResults = <int>[];
+  autorun((_) => autorunResults.add(store.value3.length));
 
- expect(autorunResults, ['first']); // length: 5
+  expect(autorunResults, [5]); // length: 5
 
- // length: 5, should not trigger
- store.value3 = 'third';
+  // length: 5, should not trigger
+  store.value3 = 'third';
 
- expect(autorunResults, ['first']);
+  expect(autorunResults, [5]);
 
- // length: 6, should trigger
- store.value3 = 'second';
+  // length: 6, should trigger
+  store.value3 = 'second';
 
- expect(autorunResults, ['first', 'second']);
- });
+ expect(autorunResults, [5, 6]);
+ });
+
+ test(
+ 'when write to iterable @observable field with unchanged value, should not trigger notifications for downstream',
+ () {
+ final store = _ExampleStore();
+
+ final autorunResults = <List<String>>[];
+ autorun((_) => autorunResults.add(store.list));
+
+ store.list = ['first'];
+ expect(autorunResults, [
+ ['first']
+ ]);
+
+ store.list = ['first'];
+ expect(autorunResults, [
+ ['first']
+ ]);
+
+ store.list = ['first'];
+ expect(autorunResults, [
+ ['first']
+ ]);
+ });
+
+ test(
+ 'when write to map @observable field with unchanged value, should not trigger notifications for downstream',
+ () {
+ final store = _ExampleStore();
+
+ final autorunResults = <Map<String, int>>[];
+ autorun((_) => autorunResults.add(store.map));
+
+ store.map = {'first': 1};
+ expect(autorunResults, [
+ {'first': 1}
+ ]);
+
+ store.map = {'first': 1};
+ expect(autorunResults, [
+ {'first': 1}
+ ]);
+
+ store.map = {'first': 1};
+ expect(autorunResults, [
+ {'first': 1}
+ ]);
+ });
 }
 
 class _ExampleStore = __ExampleStore with _$_ExampleStore;
 
-bool _equals(String? oldValue, String? newValue) => (oldValue == newValue);
+bool _equals(String? oldValue, String? newValue) => (oldValue?.length == newValue?.length);
 
 abstract class __ExampleStore with Store {
  @observable
@@ -83,6 +131,12 @@ abstract class __ExampleStore with Store {
 
  @MakeObservable(equals: _equals)
  String value3 = 'first';
+
+ @observable
+ List<String> list = ['first'];
+
+ @observable
+ Map<String, int> map = {'first': 1};
 }
 
 // This is what typically a mobx codegen will generate.
@@ -105,7 +159,7 @@ mixin _$_ExampleStore on __ExampleStore, Store {
 
  // ignore: non_constant_identifier_names
  late final _$value2Atom =
-  Atom(name: '__ExampleStore.value2', context: context);
+ Atom(name: '__ExampleStore.value2', context: context);
 
  @override
  String get value2 {
@@ -122,7 +176,7 @@ mixin _$_ExampleStore on __ExampleStore, Store {
 
  // ignore: non_constant_identifier_names
  late final _$value3Atom =
-  Atom(name: '__ExampleStore.value3', context: context);
+ Atom(name: '__ExampleStore.value3', context: context);
 
  @override
  String get value3 {
@@ -135,7 +189,38 @@ mixin _$_ExampleStore on __ExampleStore, Store {
  _$value3Atom.reportWrite(value, super.value3, () {
  super.value3 = value;
  },
- equals: (String? oldValue, String? newValue) =>
- oldValue?.length == newValue?.length);
+ equals: _equals);
+ }
+
+ // ignore: non_constant_identifier_names
+ late final _$listAtom = Atom(name: '__ExampleStore.list', context: context);
+
+ @override
+ List<String> get list {
+ _$listAtom.reportRead();
+ return super.list;
+ }
+
+ @override
+ set list(List<String> value) {
+ _$listAtom.reportWrite(value, super.list, () {
+ super.list = value;
+ });
+ }
+
+ // ignore: non_constant_identifier_names
+ late final _$mapAtom = Atom(name: '__ExampleStore.map', context: context);
+
+ @override
+ Map<String, int> get map {
+ _$mapAtom.reportRead();
+ return super.map;
+ }
+
+ @override
+ set map(Map<String, int> value) {
+ _$mapAtom.reportWrite(value, super.map, () {
+ super.map = value;
+ });
  }
 }