moor_flutter: Don't upgrade schema when migration throws (#584)

extras/integration_tests/flutter_db/pubspec.lock

@@ -173,14 +173,14 @@ packages:
       path: "../../../moor"
       relative: true
     source: path
-    version: "3.0.0"
+    version: "3.1.0"
   moor_ffi:
     dependency: "direct main"
     description:
       path: "../../../moor_ffi"
       relative: true
     source: path
-    version: "0.5.0-dev"
+    version: "0.6.0"
   moor_flutter:
     dependency: "direct main"
     description:

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

@@ -58,4 +58,30 @@ void migrationTests(TestExecutor executor) {
 
     await database.close();
   });
+
+  test('does not apply schema version when migration throws', () async {
+    var database = Database(executor.createConnection(), schemaVersion: 1);
+    await database.executor.ensureOpen(database); // Create the database
+    await database.close();
+
+    database = Database(executor.createConnection(), schemaVersion: 2);
+    database.overrideMigration = MigrationStrategy(
+      onUpgrade: (m, from, to) => Future.error('oops'),
+    );
+
+    try {
+      await database.executor.ensureOpen(database);
+      fail('Should have thrown');
+    } catch (e) {
+      //ignore
+      await database.close();
+    }
+
+    // Open it one last time, the schema version should still be at 1
+    database = Database(executor.createConnection(), schemaVersion: 1);
+    final result =
+        await database.customSelect('PRAGMA user_version').getSingle();
+    expect(result.data.values.single, 1);
+    await database.close();
+  });
 }

moor_flutter/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.1.0
+
+Don't write the schema version to the database if the migration throws an exception.
+
 ## 3.0.0
 
 Support `moor` version 3.0. To learn what's new, head over to [its changelog](https://pub.dev/packages/moor).

moor_flutter/lib/moor_flutter.dart

@@ -20,7 +20,6 @@ export 'package:moor/moor.dart';
 typedef DatabaseCreator = FutureOr<void> Function(File file);
 
 class _SqfliteDelegate extends DatabaseDelegate with _SqfliteExecutor {
-  int _loadedSchemaVersion;
   @override
   s.Database db;
 
@@ -35,9 +34,10 @@ class _SqfliteDelegate extends DatabaseDelegate with _SqfliteExecutor {
     singleInstance ??= true;
   }
 
+  DbVersionDelegate _delegate;
   @override
   DbVersionDelegate get versionDelegate {
-    return OnOpenVersionDelegate(() => Future.value(_loadedSchemaVersion));
+    return _delegate ??= _SqfliteVersionDelegate(db);
   }
 
   @override
@@ -62,20 +62,8 @@ class _SqfliteDelegate extends DatabaseDelegate with _SqfliteExecutor {
     }
 
     // default value when no migration happened
-    _loadedSchemaVersion = user.schemaVersion;
-
     db = await s.openDatabase(
       resolvedPath,
-      version: user.schemaVersion,
-      onCreate: (db, version) {
-        _loadedSchemaVersion = 0;
-      },
-      onUpgrade: (db, from, to) {
-        _loadedSchemaVersion = from;
-      },
-      onDowngrade: (db, from, to) {
-        _loadedSchemaVersion = from;
-      },
       singleInstance: singleInstance,
     );
   }
@@ -86,6 +74,23 @@ class _SqfliteDelegate extends DatabaseDelegate with _SqfliteExecutor {
   }
 }
 
+class _SqfliteVersionDelegate extends DynamicVersionDelegate {
+  final s.Database _db;
+
+  _SqfliteVersionDelegate(this._db);
+
+  @override
+  Future<int> get schemaVersion async {
+    final result = await _db.rawQuery('PRAGMA user_version;');
+    return result.single.values.first as int;
+  }
+
+  @override
+  Future<void> setSchemaVersion(int version) async {
+    await _db.rawUpdate('PRAGMA user_version = $version;');
+  }
+}
+
 class _SqfliteTransactionDelegate extends SupportedTransactionDelegate {
   final _SqfliteDelegate delegate;
 

moor_flutter/pubspec.yaml

@@ -1,6 +1,6 @@
 name: moor_flutter
 description: Flutter implementation of moor, a safe and reactive persistence library for Dart applications
-version: 3.0.0
+version: 3.1.0
 repository: https://github.com/simolus3/moor
 homepage: https://moor.simonbinder.eu/
 issue_tracker: https://github.com/simolus3/moor/issues