return if no dataset card is available

main.py

@@ -5,11 +5,12 @@ from typing import List, Optional
 import chromadb
 from cashews import cache
 from fastapi import FastAPI, HTTPException, Query
+from httpx import AsyncClient
+from huggingface_hub import DatasetCard
 from pydantic import BaseModel
 from starlette.responses import RedirectResponse
-from httpx import AsyncClient
+
 from load_data import get_embedding_function, get_save_path, refresh_data
-from huggingface_hub import DatasetCard
 
 # Set up logging
 logging.basicConfig(
@@ -87,7 +88,7 @@ async def try_get_card(hub_id: str) -> Optional[str]:
         return None
 
 
-@app.get("/similar", response_model=Optional[QueryResponse])
+@app.get("/similar", response_model=QueryResponse)
 @cache(ttl="1h")
 async def api_query_dataset(dataset_id: str, n: int = Query(default=10, ge=1, le=100)):
     try:
@@ -99,6 +100,8 @@ async def api_query_dataset(dataset_id: str, n: int = Query(default=10, ge=1, le
             try:
                 embedding_function = get_embedding_function()
                 card = await try_get_card(dataset_id)
+                if card is None:
+                    return QueryResponse(message="No dataset card available for recommendations.")
                 embeddings = embedding_function(card)
                 collection.upsert(ids=[dataset_id], embeddings=embeddings[0])
                 logger.info(f"Dataset {dataset_id} added to collection")
@@ -107,7 +110,7 @@ async def api_query_dataset(dataset_id: str, n: int = Query(default=10, ge=1, le
                 logger.error(
                     f"Error adding dataset {dataset_id} to collection: {str(e)}"
                 )
-                raise HTTPException(status_code=404, detail="Dataset not found") from e
+                return QueryResponse(message="No dataset card available for recommendations.")
 
         embedding = result["embeddings"][0]
 
@@ -118,7 +121,7 @@ async def api_query_dataset(dataset_id: str, n: int = Query(default=10, ge=1, le
 
         if not query_result["ids"]:
             logger.info(f"No similar datasets found for: {dataset_id}")
-            return None
+            return QueryResponse(message="No similar datasets found.")
 
         # Prepare the response
         results = [
@@ -133,8 +136,7 @@ async def api_query_dataset(dataset_id: str, n: int = Query(default=10, ge=1, le
 
     except Exception as e:
         logger.error(f"Error querying dataset {dataset_id}: {str(e)}")
-        raise HTTPException(status_code=500, detail=str(e)) from e
-
+        raise HTTPException(status_code=500, detail=str(e))
 
 if __name__ == "__main__":
     import uvicorn