Fix reading from fsspec s3 (#130)

* Fix pointer not at the start of the file error

* whatsnew

Co-authored-by: William Roberts <wroberts@hadamard.ssec.wisc.edu>
Co-authored-by: Tom Nicholas <thomas.nicholas@columbia.edu>

Author: 3 people

datatree/io.py

@@ -63,9 +63,9 @@ def open_datatree(filename_or_obj, engine=None, **kwargs) -> DataTree:
 def _open_datatree_netcdf(filename: str, **kwargs) -> DataTree:
     ncDataset = _get_nc_dataset_class(kwargs.get("engine", None))
 
+    ds = open_dataset(filename, **kwargs)
+    tree_root = DataTree.from_dict({"/": ds})
     with ncDataset(filename, mode="r") as ncds:
-        ds = open_dataset(filename, **kwargs)
-        tree_root = DataTree.from_dict({"/": ds})
         for path in _iter_nc_groups(ncds):
             subgroup_ds = open_dataset(filename, group=path, **kwargs)
 

docs/source/whats-new.rst

@@ -46,6 +46,10 @@ Documentation
 Internal Changes
 ~~~~~~~~~~~~~~~~
 
+- Avoid reading from same file twice with fsspec3 (:pull:`130`)
+  By `William Roberts <https://github.com/wroberts4>`_.
+
+
 .. _whats-new.v0.0.9:
 
 v0.0.9 (07/14/2022)