fix deletion of shows

store/shows.go

@@ -178,13 +178,37 @@ func (st *Store) CloneShow(name, from string) (show *Show, err error) {
 }
 
 // this will also remove all files and playlists belonging to the show!
-// TODO: fix cascading errors (deletion of files is tried before deletion of playlists
-//       which does not work when files are still refrenced by playlists...
-func (st *Store) DeleteShow(name string) error {
-	if err := st.db.Delete(&Show{Name: name}).Error; err != nil {
-		return err
+func (st *Store) DeleteShow(name string) (err error) {
+	tx := st.db.Begin()
+	defer func() {
+		if r := recover(); r != nil {
+			tx.Rollback()
+			if err == nil {
+				err = fmt.Errorf("runtime panic: %+v", r)
+			}
+		}
+	}()
+
+	// We have to delete the playlists first since by default files are deleted before
+	// playlists which does not work as long as there are playlists that reference the files
+	// to be deleted.
+	// As soon as playlists are gone, deleting the show will cascade to delete
+	// the files as well.
+	if err = tx.Where("show_name = ?", name).Delete(&Playlist{}).Error; err != nil {
+		tx.Rollback()
+		return
+	}
+	if err = tx.Delete(&Show{Name: name}).Error; err != nil {
+		tx.Rollback()
+		return
 	}
-	return os.RemoveAll(st.getShowPath(name))
+	if err = os.RemoveAll(st.getShowPath(name)); err != nil {
+		tx.Rollback()
+		return
+	}
+
+	err = tx.Commit().Error
+	return
 }
 
 func (st *Store) ListShows() (shows Shows, err error) {