From 5ff78b859a263ff2ab85d0f0ede3abf15b91b543 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Thu, 23 Nov 2023 22:30:07 +0100
Subject: [PATCH 1/3] Fix bug for categorical pandas index with categories with
 EA dtype

---
 xarray/core/utils.py         |  2 ++
 xarray/tests/test_dataset.py | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/xarray/core/utils.py b/xarray/core/utils.py
index ad86b2c7fec..9ba4a43f6d9 100644
--- a/xarray/core/utils.py
+++ b/xarray/core/utils.py
@@ -114,6 +114,8 @@ def get_valid_numpy_dtype(array: np.ndarray | pd.Index):
     elif hasattr(array, "categories"):
         # category isn't a real numpy dtype
         dtype = array.categories.dtype
+        if not is_valid_numpy_dtype(dtype):
+            dtype = np.dtype("O")
     elif not is_valid_numpy_dtype(array.dtype):
         dtype = np.dtype("O")
     else:
diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
index ff7703a1cf5..6a1261fcd32 100644
--- a/xarray/tests/test_dataset.py
+++ b/xarray/tests/test_dataset.py
@@ -4697,6 +4697,17 @@ def test_from_dataframe_categorical(self) -> None:
         assert len(ds["i1"]) == 2
         assert len(ds["i2"]) == 2
 
+    def test_from_dataframe_categorical_string_categories(self):
+        cat = pd.CategoricalIndex(
+            pd.Categorical.from_codes(
+                np.array([1, 1, 0, 2]),
+                categories=pd.Index(["foo", "bar", "baz"], dtype="string"),
+            )
+        )
+        ser = pd.Series(1, index=cat)
+        ds = ser.to_xarray()
+        assert ds.coords.dtypes["index"] == np.dtype("O")
+
     @requires_sparse
     def test_from_dataframe_sparse(self) -> None:
         import sparse

From e4452c115bbd19dbb0602bb1ca85a7c5e334cdb7 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Thu, 23 Nov 2023 22:33:14 +0100
Subject: [PATCH 2/3] Add whatsnew

---
 doc/whats-new.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index 76548fe95c5..3a947daf153 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -42,6 +42,8 @@ Deprecations
 Bug fixes
 ~~~~~~~~~
 
+- Fix dtype inference for ``pd.CategoricalIndex`` when categories are backed by a ``pd.ExtensionDtype`` (:pull:`8481`)
+
 
 Documentation
 ~~~~~~~~~~~~~

From ae99fdd64fc1b1b856d1ff51d3f2fef73cc28039 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Fri, 24 Nov 2023 15:06:23 +0100
Subject: [PATCH 3/3] Update xarray/tests/test_dataset.py

Co-authored-by: Illviljan <14371165+Illviljan@users.noreply.github.com>
---
 xarray/tests/test_dataset.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
index 6a1261fcd32..a53d81e36af 100644
--- a/xarray/tests/test_dataset.py
+++ b/xarray/tests/test_dataset.py
@@ -4697,7 +4697,7 @@ def test_from_dataframe_categorical(self) -> None:
         assert len(ds["i1"]) == 2
         assert len(ds["i2"]) == 2
 
-    def test_from_dataframe_categorical_string_categories(self):
+    def test_from_dataframe_categorical_string_categories(self) -> None:
         cat = pd.CategoricalIndex(
             pd.Categorical.from_codes(
                 np.array([1, 1, 0, 2]),