APIv2: pass user defined filename_or_obj to backends as is (#4707)

* Pass filename_or_obj as passed by the user to beckends

* Code style

* Fix autodetection to also accept pathlib.Path

* ensure _get_default_engine get an str object

xarray/backends/api.py

@@ -1,4 +1,5 @@
 import os
+import pathlib
 import warnings
 from glob import glob
 from io import BytesIO
@@ -144,7 +145,7 @@ def _get_engine_from_magic_number(filename_or_obj):
     return engine
 
 
-def _get_default_engine(path, allow_remote=False):
+def _get_default_engine(path: str, allow_remote: bool = False):
     if allow_remote and is_remote_uri(path):
         engine = _get_default_engine_remote_uri()
     elif is_grib_path(path):
@@ -159,8 +160,8 @@ def _get_default_engine(path, allow_remote=False):
 def _autodetect_engine(filename_or_obj):
     if isinstance(filename_or_obj, AbstractDataStore):
         engine = "store"
-    elif isinstance(filename_or_obj, str):
-        engine = _get_default_engine(filename_or_obj, allow_remote=True)
+    elif isinstance(filename_or_obj, (str, pathlib.Path)):
+        engine = _get_default_engine(str(filename_or_obj), allow_remote=True)
     else:
         engine = _get_engine_from_magic_number(filename_or_obj)
     return engine

xarray/backends/apiv2.py

@@ -7,7 +7,6 @@
 from .api import (
     _autodetect_engine,
     _get_backend_cls,
-    _normalize_path,
     _protect_dataset_variables_inplace,
 )
 
@@ -245,8 +244,6 @@ def open_dataset(
     if backend_kwargs is None:
         backend_kwargs = {}
 
-    filename_or_obj = _normalize_path(filename_or_obj)
-
     if engine is None:
         engine = _autodetect_engine(filename_or_obj)