Feat: support cross-lang search. (#7557)

### What problem does this PR solve?

#7376
#4503
#5710 
#7470

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/services/document_service.py

@@ -131,7 +131,7 @@ class DocumentService(CommonService):
         if types:
             query = query.where(cls.model.type.in_(types))
 
-        return query.scalar() or 0
+        return int(query.scalar()) or 0
 
     @classmethod
     @DB.connection_context()