add comments to backend code

backend/endpoints/rom.py

@@ -478,6 +478,7 @@ def get_roms(
         platforms=[],
     )
     if with_filter_values:
+        # We use the unfiltered query so applied filters don't affect the list
         filter_query = db_rom_handler.filter_roms(
             query=unfiltered_query,
             user_id=request.user.id,

backend/handler/database/roms_handler.py

@@ -1286,6 +1286,9 @@ class DBRomsHandler(DBBaseHandler):
         query: Query,
         session: Session = None,  # type: ignore
     ) -> dict:
+        """
+        Returns the list of filters given the current subset of ROMs in the query
+        """
         ids_subq = query.with_only_columns(Rom.id).scalar_subquery()  # type: ignore
 
         statement = (
@@ -1313,6 +1316,9 @@ class DBRomsHandler(DBBaseHandler):
         self,
         session: Session = None,  # type: ignore
     ) -> dict:
+        """
+        Returns all filter values across all ROM metadata
+        """
         statement = select(
             RomMetadata.genres,
             RomMetadata.franchises,