Query: fix obx_query_find_ids_by_score() empty result

Author: greenrobot

objectbox/query.py

@@ -110,11 +110,10 @@ def find_ids_by_score_numpy(self) -> np.array:
         try:
             c_id_array: OBX_id_array = c_id_array_p.contents
             c_count = c_id_array.count
-            if c_count == 0:
-                return []
-            c_ids = ctypes.cast(c_id_array.ids, ctypes.POINTER(obx_id))
             numpy_array = np.empty(c_count, dtype=np.uint64)
-            ctypes.memmove(numpy_array.ctypes.data, c_ids, numpy_array.nbytes)
+            if c_count > 0:
+                c_ids = ctypes.cast(c_id_array.ids, ctypes.POINTER(obx_id))
+                ctypes.memmove(numpy_array.ctypes.data, c_ids, numpy_array.nbytes)
             return numpy_array
         finally:
             obx_id_array_free(c_id_array_p)

tests/test_hnsw.py

@@ -192,6 +192,16 @@ def _test_combined_nn_search(distance_type: VectorDistanceType = VectorDistanceT
     assert search_results[0] == 4
     assert search_results[1] == 5
 
+    # Test empty result
+    query.offset(999)
+    assert len(query.find_ids()) == 0
+    assert len(query.find_ids_with_scores()) == 0
+    assert len(query.find_ids_by_score()) == 0
+    numpy_result = query.find_ids_by_score_numpy()
+    assert numpy_result.size == 0
+    assert str(numpy_result.dtype) == "uint64"
+    assert len(numpy_result) == 0
+
 
 def test_combined_nn_search():
     """ Tests NN search combined with regular query conditions, offset and limit. """