Fix migrations not running for drift_sqlite_async.

Author: rkistner

packages/drift_sqlite_async/example/main.g.dart

@@ -21,21 +21,18 @@ class AppDatabase extends _$AppDatabase {
 
   @override
   MigrationStrategy get migration {
-    return MigrationStrategy(
-      onCreate: (m) async {
-        // In this example, the schema is managed by Drift
-        await m.createAll();
-      },
-    );
+    return MigrationStrategy(onCreate: (m) async {
+      // In this example, the schema is managed by Drift.
+      // For more options, see:
+      // https://drift.simonbinder.eu/migrations/#usage
+      await m.createAll();
+    });
   }
 }
 
 Future<void> main() async {
   final db = SqliteDatabase(path: 'with_migrations.db');
 
-  await db.execute(
-      'CREATE TABLE IF NOT EXISTS todos(id integer primary key, description text)');
-
   final appdb = AppDatabase(db);
 
   // Watch a query on the Drift database

packages/drift_sqlite_async/example/with_migrations.dart

@@ -15,6 +15,7 @@ class _SqliteAsyncDelegate extends _SqliteAsyncQueryDelegate
     implements DatabaseDelegate {
   final SqliteConnection db;
   bool _closed = false;
+  bool _calledOpen = false;
 
   _SqliteAsyncDelegate(this.db) : super(db, db.writeLock);
 
@@ -30,12 +31,15 @@ class _SqliteAsyncDelegate extends _SqliteAsyncQueryDelegate
       _SqliteAsyncTransactionDelegate(db);
 
   @override
-  bool get isOpen => !db.closed && !_closed;
+  bool get isOpen => !db.closed && !_closed && _calledOpen;
 
   @override
   Future<void> open(QueryExecutorUser user) async {
     // Workaround - this ensures the db is open
     await db.get('SELECT 1');
+    // We need to delay this until open() has been called, otherwise
+    // migrations don't run.
+    _calledOpen = true;
   }
 
   @override

packages/drift_sqlite_async/example/with_migrations.g.dart

@@ -19,3 +19,16 @@ class TodoDatabase extends _$TodoDatabase {
   @override
   int get schemaVersion => 1;
 }
+
+class TodosMigrationDatabase extends TodoDatabase {
+  TodosMigrationDatabase(SqliteConnection db) : super(db);
+
+  @override
+  MigrationStrategy get migration {
+    return MigrationStrategy(
+      onCreate: (m) async {
+        await m.createAll();
+      },
+    );
+  }
+}