correct mismatched kb doc number (#826)

### What problem does this PR solve?

#620

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/db/services/knowledgebase_service.py

@@ -112,3 +112,8 @@ class KnowledgebaseService(CommonService):
         if kb:
             return True, kb[0]
         return False, None
+
+    @classmethod
+    @DB.connection_context()
+    def get_all_ids(cls):
+        return [m["id"] for m in cls.model.select(cls.model.id).dicts()]