Add a required QueryExecutor argument to transaction

callbacks.

angel_orm/CHANGELOG.md

@@ -1,6 +1,8 @@
 # 2.1.0
 * Split the formerly 600+ line `src/query.dart` up into
 separate files.
+* **BREAKING**: Add a required `QueryExecutor` argument to `transaction`
+callbacks.
 
 # 2.0.1
 * Apply `package:pedantic` fixes.

angel_orm/example/main.dart

@@ -34,7 +34,7 @@ class _FakeExecutor extends QueryExecutor {
   }
 
   @override
-  Future<T> transaction<T>(FutureOr<T> Function() f) {
+  Future<T> transaction<T>(FutureOr<T> Function(QueryExecutor) f) {
     throw UnsupportedError('Transactions are not supported.');
   }
 }

angel_orm/lib/src/query.dart

@@ -263,9 +263,9 @@ abstract class Query<T, Where extends QueryWhere> extends QueryBase<T> {
               fields.map(adornWithTableName).toList())
           .then((it) => it.map(deserialize).toList());
     } else {
-      return executor.transaction(() async {
+      return executor.transaction((tx) async {
         // TODO: Can this be done with just *one* query?
-        var existing = await get(executor);
+        var existing = await get(tx);
         //var sql = compile(preamble: 'SELECT $tableName.id', withFields: false);
         return executor
             .query(tableName, sql, substitutionValues)

angel_orm/lib/src/query_executor.dart

@@ -11,6 +11,13 @@ abstract class QueryExecutor {
       String tableName, String query, Map<String, dynamic> substitutionValues,
       [List<String> returningFields]);
 
-  /// Begins a database transaction.
-  Future<T> transaction<T>(FutureOr<T> f());
+  /// Enters a database transaction, performing the actions within,
+  /// and returning the results of [f].
+  ///
+  /// If [f] fails, the transaction will be rolled back, and the
+  /// responsible exception will be re-thrown.
+  /// 
+  /// Whether nested transactions are supported depends on the
+  /// underlying driver.
+  Future<T> transaction<T>(FutureOr<T> Function(QueryExecutor) f);
 }