BUG: DataFrame.getattribute raising if columns have dtype string (pandas-dev#46301)

Author: phofl

doc/source/whatsnew/v1.5.0.rst

@@ -394,6 +394,7 @@ Indexing
 - Bug in :meth:`Series.mask` with ``inplace=True`` or setting values with a boolean mask with small integer dtypes incorrectly raising (:issue:`45750`)
 - Bug in :meth:`DataFrame.mask` with ``inplace=True`` and ``ExtensionDtype`` columns incorrectly raising (:issue:`45577`)
 - Bug in getting a column from a DataFrame with an object-dtype row index with datetime-like values: the resulting Series now preserves the exact object-dtype Index from the parent DataFrame (:issue:`42950`)
+- Bug in :meth:`DataFrame.__getattribute__` raising ``AttributeError`` if columns have ``"string"`` dtype (:issue:`46185`)
 - Bug in indexing on a :class:`DatetimeIndex` with a ``np.str_`` key incorrectly raising (:issue:`45580`)
 - Bug in :meth:`CategoricalIndex.get_indexer` when index contains ``NaN`` values, resulting in elements that are in target but not present in the index to be mapped to the index of the NaN element, instead of -1 (:issue:`45361`)
 - Bug in setting large integer values into :class:`Series` with ``float32`` or ``float16`` dtype incorrectly altering these values instead of coercing to ``float64`` dtype (:issue:`45844`)

pandas/core/indexes/base.py

@@ -97,6 +97,7 @@
     is_object_dtype,
     is_scalar,
     is_signed_integer_dtype,
+    is_string_dtype,
     is_unsigned_integer_dtype,
     needs_i8_conversion,
     pandas_dtype,
@@ -5276,7 +5277,7 @@ def _can_hold_identifiers_and_holds_name(self, name) -> bool:
 
         https://github.com/pandas-dev/pandas/issues/19764
         """
-        if self.is_object() or self.is_categorical():
+        if self.is_object() or is_string_dtype(self.dtype) or self.is_categorical():
             return name in self
         return False
 

pandas/tests/frame/indexing/test_getitem.py

@@ -72,6 +72,13 @@ def test_getitem_sparse_column_return_type_and_dtype(self):
         result = df.loc[:, "A"]
         tm.assert_series_equal(result, expected)
 
+    def test_getitem_string_columns(self):
+        # GH#46185
+        df = DataFrame([[1, 2]], columns=Index(["A", "B"], dtype="string"))
+        result = df.A
+        expected = df["A"]
+        tm.assert_series_equal(result, expected)
+
 
 class TestGetitemListLike:
     def test_getitem_list_missing_key(self):