fix(shortcuts): fix premature rows closure in QueryIterContext (#545)

The previous implementation called defer rows.Close() before returning
the iterator, which caused rows to be closed immediately when the function
returned, making the iterator unusable.

Now the iterator wraps the close logic, ensuring rows are closed only
after iteration completes or stops.

Author: eatmoreapple

shortcuts.go

@@ -79,6 +79,9 @@ func QueryList2Context[T any](ctx context.Context, statement, param any) (result
 // QueryIterContext executes a query and returns an iterator over T.
 // Rows are automatically closed when iteration completes or stops.
 // (ctx must contain a Manager via ManagerFromContext)
+//
+// IMPORTANT: The returned iterator MUST be iterated over (even partially),
+// otherwise the underlying database rows will not be closed, leading to resource leaks.
 func QueryIterContext[T any](ctx context.Context, statement, param any) (sqllib.Iterator[T], error) {
 	manager, err := ManagerFromContext(ctx)
 	if err != nil {
@@ -88,6 +91,16 @@ func QueryIterContext[T any](ctx context.Context, statement, param any) (sqllib.
 	if err != nil {
 		return nil, err
 	}
-	defer func() { _ = rows.Close() }()
-	return sqllib.Iter[T](rows)
+
+	iterator, err := sqllib.Iter[T](rows)
+	if err != nil {
+		_ = rows.Close()
+		return nil, err
+	}
+
+	// Wrap the iterator to ensure rows are closed after iteration
+	return func(yield func(T, error) bool) {
+		defer func() { _ = rows.Close() }()
+		iterator(yield)
+	}, nil
 }