[fix] Fix loading pre-exported OV/ONNX model if export=False (#3036)

sentence_transformers/models/Transformer.py

@@ -255,7 +255,7 @@ def _backend_should_export(
         """
 
         export = model_args.pop("export", None)
-        if export is not None:
+        if export:
             return export, model_args
 
         file_name = model_args.get("file_name", target_file_name)
@@ -283,17 +283,19 @@ def _backend_should_export(
         # First check if the expected file exists in the root of the model directory
         # If it doesn't, check if it exists in the backend subfolder.
         # If it does, set the subfolder to include the backend
-        export = primary_full_path not in model_file_names
-        if export and "subfolder" not in model_args:
-            export = secondary_full_path not in model_file_names
-            if not export:
+        model_found = primary_full_path in model_file_names
+        if not model_found and "subfolder" not in model_args:
+            model_found = secondary_full_path in model_file_names
+            if model_found:
                 if len(model_file_names) > 1 and "file_name" not in model_args:
                     logger.warning(
                         f"Multiple {backend_name} files found in {load_path.as_posix()!r}: {model_file_names}, defaulting to {secondary_full_path!r}. "
                         f'Please specify the desired file name via `model_kwargs={{"file_name": "<file_name>"}}`.'
                     )
                 model_args["subfolder"] = self.backend
                 model_args["file_name"] = file_name
+        if export is None:
+            export = not model_found
 
         # If the file_name contains subfolders, set it as the subfolder instead
         file_name_parts = Path(file_name).parts

tests/test_backends.py

@@ -156,3 +156,38 @@ def test_openvino_backend() -> None:
         ), "OpenVINO saved model output differs from in-memory converted model"
         del local_openvino_model
         gc.collect()
+
+
+def test_export_false_subfolder() -> None:
+    model_id = "sentence-transformers-testing/stsb-bert-tiny-openvino"
+
+    def from_pretrained_decorator(method):
+        def decorator(*args, **kwargs):
+            assert not kwargs["export"]
+            assert kwargs["subfolder"] == "openvino"
+            assert kwargs["file_name"] == "openvino_model.xml"
+            return method(*args, **kwargs)
+
+        return decorator
+
+    OVModelForFeatureExtraction.from_pretrained = from_pretrained_decorator(
+        OVModelForFeatureExtraction.from_pretrained
+    )
+    SentenceTransformer(model_id, backend="openvino", model_kwargs={"export": False})
+
+
+def test_export_set_nested_filename() -> None:
+    model_id = "sentence-transformers-testing/stsb-bert-tiny-openvino"
+
+    def from_pretrained_decorator(method):
+        def decorator(*args, **kwargs):
+            assert kwargs["subfolder"] == "openvino"
+            assert kwargs["file_name"] == "openvino_model.xml"
+            return method(*args, **kwargs)
+
+        return decorator
+
+    OVModelForFeatureExtraction.from_pretrained = from_pretrained_decorator(
+        OVModelForFeatureExtraction.from_pretrained
+    )
+    SentenceTransformer(model_id, backend="openvino", model_kwargs={"file_name": "openvino/openvino_model.xml"})