Provide IndexedDB backend on the web (#390)

extras/integration_tests/tests/lib/suite/crud_tests.dart

@@ -5,23 +5,20 @@ import 'package:tests/suite/suite.dart';
 void crudTests(TestExecutor executor) {
   test('inserting updates a select stream', () async {
     final db = Database(executor.createExecutor());
-    final friends = db.watchFriendsOf(1);
+    final friends = db.watchFriendsOf(1).asBroadcastStream();
 
     final a = await db.getUserById(1);
     final b = await db.getUserById(2);
 
-    final expectation = expectLater(
-      friends,
-      emitsInOrder(
-        <Matcher>[
-          isEmpty, // initial state without friendships
-          equals(<User>[b]), // after we called makeFriends(a,b)
-        ],
-      ),
-    );
+    expect(await friends.first, isEmpty);
+
+    // after we called makeFriends(a,b)
+    final expectation = expectLater(friends, emits(equals(<User>[b])));
 
     await db.makeFriends(a, b);
     await expectation;
+
+    await db.close();
   });
 
   test('IN ? expressions can be expanded', () async {
@@ -31,5 +28,7 @@ void crudTests(TestExecutor executor) {
     final result = await db.usersById([1, 2, 3]);
 
     expect(result.map((u) => u.name), ['Dash', 'Duke', 'Go Gopher']);
+
+    await db.close();
   });
 }

extras/integration_tests/tests/lib/suite/transactions.dart

@@ -56,5 +56,6 @@ void transactionTests(TestExecutor executor) {
   test('can use no-op transactions', () async {
     final db = Database(executor.createExecutor());
     await db.transaction(() => Future.value(null));
+    await db.close();
   });
 }

extras/integration_tests/web/test/initializer_test.dart

@@ -182,21 +182,33 @@ AAAAAAAAAAAAAAAAAAAAAAANAQIjaGVsbG8gd29ybGQ=
 
 void main() {
   test('can initialize database when absent', () async {
-    var didCallInitializer = false;
-    final db = WebDatabase('name', initializer: () async {
-      didCallInitializer = true;
-      return base64.decode(_rawDataBase64.replaceAll('\n', ''));
-    });
-
-    db.databaseInfo = _FakeDatabase(db);
-    await db.ensureOpen();
-    expect(didCallInitializer, isTrue);
-
-    final result = await db.runSelect('SELECT * FROM foo', const []);
-    expect(result, [
-      {'name': 'hello world'}
-    ]);
+    await _testWith(const MoorWebStorage('name'));
   });
+
+  test('can initialize database when absent - IndexedDB', () async {
+    await _testWith(MoorWebStorage.indexedDb('name'));
+  });
+}
+
+Future<void> _testWith(MoorWebStorage storage) async {
+  var didCallInitializer = false;
+  final db = WebDatabase.withStorage(storage, initializer: () async {
+    didCallInitializer = true;
+    return base64.decode(_rawDataBase64.replaceAll('\n', ''));
+  });
+
+  moorRuntimeOptions.dontWarnAboutMultipleDatabases = true;
+  db.databaseInfo = _FakeDatabase(db);
+
+  await db.ensureOpen();
+  expect(didCallInitializer, isTrue);
+
+  final result = await db.runSelect('SELECT * FROM foo', const []);
+  expect(result, [
+    {'name': 'hello world'}
+  ]);
+
+  await db.close();
 }
 
 class _FakeDatabase extends GeneratedDatabase {

extras/integration_tests/web/test/integration_test.dart

@@ -20,6 +20,24 @@ class WebExecutor extends TestExecutor {
   }
 }
 
-void main() {
-  runAllTests(WebExecutor());
+class WebExecutorIndexedDb extends TestExecutor {
+  @override
+  QueryExecutor createExecutor() {
+    return WebDatabase.withStorage(MoorWebStorage.indexedDb('foo'));
+  }
+
+  @override
+  Future deleteData() async {
+    await window.indexedDB.deleteDatabase('moor_databases');
+  }
+}
+
+void main() {
+  group('using local storage', () {
+    runAllTests(WebExecutor());
+  });
+
+  group('using IndexedDb', () {
+    runAllTests(WebExecutorIndexedDb());
+  });
 }

moor/CHANGELOG.md

@@ -1,3 +1,7 @@
+## unreleased
+
+- Experimentally support IndexedDB to store sqlite data on the web
+
 ## 2.4.0
 
 - Support aggregate expressions and `group by` in the Dart api

moor/lib/moor_web.dart

@@ -7,6 +7,7 @@ library moor_web;
 
 import 'dart:async';
 import 'dart:html';
+import 'dart:indexed_db';
 
 import 'package:meta/meta.dart';
 
@@ -17,4 +18,5 @@ import 'src/web/sql_js.dart';
 
 export 'moor.dart';
 
+part 'src/web/storage.dart';
 part 'src/web/web_db.dart';

moor/lib/src/runtime/executor/helpers/engines.dart

@@ -298,6 +298,11 @@ class DelegatedDatabase extends QueryExecutor with _ExecutorWithQueryDelegate {
   Future<void> _runBeforeOpen(OpeningDetails d) {
     return databaseInfo.beforeOpenCallback(_BeforeOpeningExecutor(this), d);
   }
+
+  @override
+  Future<void> close() {
+    return delegate.close();
+  }
 }
 
 /// Inside a `beforeOpen` callback, all moor apis must be available. At the same

moor/lib/src/web/storage.dart

@@ -0,0 +1,140 @@
+part of 'package:moor/moor_web.dart';
+
+/// Interface to control how moor should store data on the web.
+abstract class MoorWebStorage {
+  /// Opens the storage implementation.
+  Future<void> open();
+
+  /// Closes the storage implementation.
+  ///
+  /// No further requests may be sent after [close] was called.
+  Future<void> close();
+
+  /// Restore the last database version that was saved with [store].
+  ///
+  /// If no saved data was found, returns null.
+  Future<Uint8List> restore();
+
+  /// Store the entire database.
+  Future<void> store(Uint8List data);
+
+  /// Creates the default storage implementation that uses the local storage
+  /// apis.
+  ///
+  /// The [name] parameter can be used to store multiple databases.
+  const factory MoorWebStorage(String name) = _LocalStorageImpl;
+
+  /// An experimental storage implementation that uses IndexedDB.
+  ///
+  /// This implementation is significantly faster than the default
+  /// implementation in local storage. Browsers also tend to allow more data
+  /// to be saved in IndexedDB.
+  /// However, older browsers might not support IndexedDB.
+  @experimental
+  factory MoorWebStorage.indexedDb(String name) = _IndexedDbStorage;
+}
+
+abstract class _CustomSchemaVersionSave implements MoorWebStorage {
+  int /*?*/ get schemaVersion;
+  set schemaVersion(int value);
+}
+
+class _LocalStorageImpl implements MoorWebStorage, _CustomSchemaVersionSave {
+  final String name;
+
+  String get _persistenceKey => 'moor_db_str_$name';
+  String get _versionKey => 'moor_db_version_$name';
+
+  const _LocalStorageImpl(this.name);
+
+  @override
+  int get schemaVersion {
+    final versionStr = window.localStorage[_versionKey];
+    // ignore: avoid_returning_null
+    if (versionStr == null) return null;
+
+    return int.tryParse(versionStr);
+  }
+
+  @override
+  set schemaVersion(int value) {
+    window.localStorage[_versionKey] = value.toString();
+  }
+
+  @override
+  Future<void> close() => Future.value();
+
+  @override
+  Future<void> open() => Future.value();
+
+  @override
+  Future<Uint8List> restore() async {
+    final raw = window.localStorage[_persistenceKey];
+    if (raw != null) {
+      return bin2str.decode(raw);
+    }
+    return null;
+  }
+
+  @override
+  Future<void> store(Uint8List data) {
+    final binStr = bin2str.encode(data);
+    window.localStorage[_persistenceKey] = binStr;
+
+    return Future.value();
+  }
+}
+
+class _IndexedDbStorage implements MoorWebStorage {
+  static const _objectStoreName = 'moor_databases';
+
+  final String name;
+
+  Database _database;
+
+  _IndexedDbStorage(this.name);
+
+  @override
+  Future<void> open() async {
+    _database = await window.indexedDB.open(
+      _objectStoreName,
+      version: 1,
+      onUpgradeNeeded: (event) {
+        final database = event.target.result as Database;
+        database.createObjectStore(_objectStoreName);
+      },
+    );
+  }
+
+  @override
+  Future<void> close() async {
+    _database.close();
+  }
+
+  @override
+  Future<void> store(Uint8List data) async {
+    final transaction =
+        _database.transactionStore(_objectStoreName, 'readwrite');
+    final store = transaction.objectStore(_objectStoreName);
+
+    await store.put(Blob([data]), name);
+    await transaction.completed;
+  }
+
+  @override
+  Future<Uint8List> restore() async {
+    final transaction =
+        _database.transactionStore(_objectStoreName, 'readonly');
+    final store = transaction.objectStore(_objectStoreName);
+
+    final result = await store.getObject(name) as Blob /*?*/;
+    if (result == null) return null;
+
+    final reader = FileReader();
+    reader.readAsArrayBuffer(result);
+    // todo: Do we need to handle errors? We're reading from memory
+    await reader.onLoad.first;
+
+    return reader.result as Uint8List;
+  }
+}

moor/lib/src/web/web_db.dart

@@ -14,20 +14,28 @@ class WebDatabase extends DelegatedDatabase {
   /// [initializer] can be used to initialize the database if it doesn't exist.
   WebDatabase(String name,
       {bool logStatements = false, CreateWebDatabase initializer})
-      : super(_WebDelegate(name, initializer),
+      : super(_WebDelegate(MoorWebStorage(name), initializer),
+            logStatements: logStatements, isSequential: true);
+
+  /// A database executor that works on the web.
+  ///
+  /// The [storage] parameter controls how the data will be stored. The default
+  /// constructor of [MoorWebStorage] will use local storage for that, but an
+  /// IndexedDB-based implementation is available via.
+  WebDatabase.withStorage(MoorWebStorage storage,
+      {bool logStatements = false, CreateWebDatabase initializer})
+      : super(_WebDelegate(storage, initializer),
             logStatements: logStatements, isSequential: true);
 }
 
 class _WebDelegate extends DatabaseDelegate {
-  final String name;
+  final MoorWebStorage storage;
   final CreateWebDatabase initializer;
   SqlJsDatabase _db;
 
-  String get _persistenceKey => 'moor_db_str_$name';
-
   bool _inTransaction = false;
 
-  _WebDelegate(this.name, this.initializer);
+  _WebDelegate(this.storage, this.initializer);
 
   @override
   set isInTransaction(bool value) {
@@ -59,11 +67,13 @@ class _WebDelegate extends DatabaseDelegate {
     assert(dbVersion >= 1, 'Database schema version needs to be at least 1');
 
     final module = await initSqlJs();
-    var restored = _restoreDb();
+
+    await storage.open();
+    var restored = await storage.restore();
 
     if (restored == null && initializer != null) {
       restored = await initializer();
-      _storeData(restored);
+      await storage.store(restored);
     }
 
     _db = module.createDatabase(restored);
@@ -123,52 +133,37 @@ class _WebDelegate extends DatabaseDelegate {
   }
 
   @override
-  Future<void> close() {
-    _storeDb();
+  Future<void> close() async {
+    await _storeDb();
     _db?.close();
-    return Future.value();
+    await storage.close();
   }
 
   @override
   void notifyDatabaseOpened(OpeningDetails details) {
-    if (details.hadUpgrade | details.wasCreated) {
+    if (details.hadUpgrade || details.wasCreated) {
       _storeDb();
     }
   }
 
   /// Saves the database if the last statement changed rows. As a side-effect,
   /// saving the database resets the `last_insert_id` counter in sqlite.
-  Future<int> _handlePotentialUpdate() {
+  Future<int> _handlePotentialUpdate() async {
     final modified = _db.lastModifiedRows();
     if (modified > 0) {
-      _storeDb();
+      await _storeDb();
     }
-    return Future.value(modified);
+    return modified;
   }
 
-  Uint8List _restoreDb() {
-    final raw = window.localStorage[_persistenceKey];
-    if (raw != null) {
-      return bin2str.decode(raw);
-    }
-    return null;
-  }
-
-  void _storeDb() {
+  Future<void> _storeDb() async {
     if (!isInTransaction) {
-      _storeData(_db.export());
+      await storage.store(_db.export());
     }
   }
-
-  void _storeData(Uint8List data) {
-    final binStr = bin2str.encode(data);
-    window.localStorage[_persistenceKey] = binStr;
-  }
 }
 
 class _WebVersionDelegate extends DynamicVersionDelegate {
-  String get _versionKey => 'moor_db_version_${delegate.name}';
-
   final _WebDelegate delegate;
 
   _WebVersionDelegate(this.delegate);
@@ -179,18 +174,23 @@ class _WebVersionDelegate extends DynamicVersionDelegate {
 
   @override
   Future<int> get schemaVersion async {
-    if (!window.localStorage.containsKey(_versionKey)) {
-      return delegate._db?.userVersion;
+    final storage = delegate.storage;
+    int version;
+    if (storage is _CustomSchemaVersionSave) {
+      version = storage.schemaVersion;
     }
-    final versionStr = window.localStorage[_versionKey];
 
-    return int.tryParse(versionStr);
+    return version ?? delegate._db.userVersion;
   }
 
   @override
-  Future<void> setSchemaVersion(int version) {
+  Future<void> setSchemaVersion(int version) async {
+    final storage = delegate.storage;
+
+    if (storage is _CustomSchemaVersionSave) {
+      storage.schemaVersion = version;
+    }
+
     delegate._db.userVersion = version;
-    window.localStorage[_versionKey] = version.toString();
-    return Future.value();
   }
 }