Remove limitations of a beforeOpen callback (#216)

moor/CHANGELOG.md

@@ -1,6 +1,7 @@
 ## unreleased
 
 - Fix crash when `customStatement` is the first operation used on a database ([#199](https://github.com/simolus3/moor/issues/199))
+- Allow transactions inside a `beforeOpen` callback
 
 ## 2.0.1
 

moor/lib/src/runtime/database.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 
 import 'package:meta/meta.dart';
 import 'package:moor/moor.dart';
-import 'package:moor/src/runtime/executor/before_open.dart';
 import 'package:moor/src/runtime/executor/stream_queries.dart';
 
 const _zoneRootUserKey = #DatabaseConnectionUser;
@@ -475,15 +474,13 @@ abstract class GeneratedDatabase extends DatabaseConnectionUser
   /// is used internally by database implementations and should not be called by
   /// users.
   Future<void> beforeOpenCallback(
-      QueryExecutor executor, OpeningDetails details) async {
+      QueryExecutor executor, OpeningDetails details) {
     final migration = _resolvedMigration;
 
     if (migration.beforeOpen != null) {
-      final engine = BeforeOpenEngine(this, executor);
-      await _runEngineZoned(engine, () {
-        return migration.beforeOpen(details);
-      });
+      return migration.beforeOpen(details);
     }
+    return Future.value();
   }
 
   /// Closes this database and releases associated resources.

moor/lib/src/runtime/executor/before_open.dart

@@ -1,33 +0,0 @@
-import 'package:meta/meta.dart';
-import 'package:moor/moor.dart';
-import 'package:moor/src/runtime/executor/stream_queries.dart';
-
-/// Used internally by moor.
-class BeforeOpenEngine extends DatabaseConnectionUser with QueryEngine {
-  /// Used internally by moor.
-  BeforeOpenEngine(DatabaseConnectionUser other, QueryExecutor executor)
-      : super.delegate(
-          other,
-          executor: executor,
-          streamQueries: _IgnoreStreamQueries(),
-        );
-
-  @override
-  @alwaysThrows
-  Future<T> transaction<T>(Function action) {
-    throw UnsupportedError("Transactions can't be started inside beforeOpen");
-  }
-}
-
-class _IgnoreStreamQueries extends StreamQueryStore {
-  @override
-  Stream<T> registerStream<T>(QueryStreamFetcher<T> statement) {
-    throw StateError('Streams cannot be created inside a transaction. See the '
-        'documentation of GeneratedDatabase.transaction for details.');
-  }
-
-  @override
-  Future handleTableUpdates(Set<TableInfo> tables) {
-    return Future.value(null);
-  }
-}

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

@@ -189,33 +189,6 @@ class _TransactionExecutor extends TransactionExecutor
   }
 }
 
-class _BeforeOpeningExecutor extends QueryExecutor
-    with _ExecutorWithQueryDelegate {
-  final DelegatedDatabase db;
-
-  @override
-  QueryDelegate get impl => db.delegate;
-
-  @override
-  bool get isSequential => db.isSequential;
-
-  @override
-  bool get logStatements => db.logStatements;
-
-  _BeforeOpeningExecutor(this.db);
-
-  @override
-  TransactionExecutor beginTransaction() {
-    throw Exception(
-        "Transactions can't be started in the before open callback");
-  }
-
-  @override
-  Future<bool> ensureOpen() {
-    return Future.value(true);
-  }
-}
-
 /// A database engine (implements [QueryExecutor]) that delegated the relevant
 /// work to a [DatabaseDelegate].
 class DelegatedDatabase extends QueryExecutor with _ExecutorWithQueryDelegate {
@@ -301,6 +274,6 @@ class DelegatedDatabase extends QueryExecutor with _ExecutorWithQueryDelegate {
   }
 
   Future<void> _runBeforeOpen(OpeningDetails d) {
-    return databaseInfo.beforeOpenCallback(_BeforeOpeningExecutor(this), d);
+    return databaseInfo.beforeOpenCallback(this, d);
   }
 }