fix: support accessing RNTuple fields by full path (#1466)

* Support accessing RNTuple fields by full path

* Added tests

* Fixed other error message

Author: ariostas

src/uproot/reading.py

@@ -2088,7 +2088,7 @@ def __getitem__(self, where):
                                 raise uproot.KeyInFileError(
                                     where,
                                     because=repr(head)
-                                    + " is not a TDirectory, TTree, or TBranch",
+                                    + " is not a TDirectory, TTree, TBranch, RNTuple, or RField",
                                     keys=[key.fName for key in last._keys],
                                     file_path=self._file.file_path,
                                 )
@@ -2098,14 +2098,20 @@ def __getitem__(self, where):
                             last = step
                             step = step[item]
 
-                    elif isinstance(step, uproot.behaviors.TBranch.HasBranches):
+                    elif isinstance(
+                        step,
+                        (
+                            uproot.behaviors.TBranch.HasBranches,
+                            uproot.behaviors.RNTuple.HasFields,
+                        ),
+                    ):
                         return step["/".join(items[i:])]
 
                     else:
                         raise uproot.KeyInFileError(
                             where,
                             because="/".join(items[:i])
-                            + " is not a TDirectory, TTree, or TBranch",
+                            + " is not a TDirectory, TTree, TBranch, RNTuple, or RField",
                             keys=[key.fName for key in last._keys],
                             file_path=self._file.file_path,
                         )

tests/test_1250_rntuple_improvements.py

@@ -12,12 +12,20 @@ def test_field_class():
         obj = f["ntuple"]
         my_struct = obj["my_struct"]
         assert len(my_struct) == 2
+        assert my_struct is f["ntuple/my_struct"]
+        assert my_struct is f["ntuple"]["my_struct"]
 
         sub_struct = my_struct["sub_struct"]
         assert len(my_struct) == 2
+        assert sub_struct is f["ntuple/my_struct/sub_struct"]
+        assert sub_struct is f["ntuple"]["my_struct"]["sub_struct"]
 
         sub_sub_struct = sub_struct["sub_sub_struct"]
         assert len(sub_sub_struct) == 2
+        assert sub_sub_struct is f["ntuple/my_struct/sub_struct/sub_sub_struct"]
+        assert (
+            sub_sub_struct is f["ntuple"]["my_struct"]["sub_struct"]["sub_sub_struct"]
+        )
 
         v = sub_sub_struct["v"]
         assert len(v) == 1