Implement the save_all method.

backend/application/src/video/service.rs

@@ -20,19 +20,21 @@ impl VideoService {
 
     pub fn list_root_folder(&self) -> Result<Vec<LibraryItem>, VideoError> {
         let read_items_with_possibly_no_id = self.video_port.list_root_folder()?;
-        
+
         let new_items = read_items_with_possibly_no_id.iter()
             .filter(|item| item.id.is_none())
             .map(LibraryRawItem::map_to_library_item)
-            .collect();
-        
+            .collect::<Vec<LibraryItem>>();
+
         let already_existing_items = read_items_with_possibly_no_id.iter()
             .filter(|item| item.id.is_some())
             .map(LibraryRawItem::map_to_library_item)
             .collect::<Vec<LibraryItem>>();
-        
-        self.video_port.save_all(&new_items)?;
-        
+
+        if !new_items.is_empty() {
+            self.video_port.save_all(&new_items)?;
+        }
+
         let all_items = already_existing_items.into_iter().chain(new_items).collect();
         Ok(all_items)
     }