BUG: Decimal(NaN) incorrectly allowed in ArrowEA constructor with timestamp type

Author: jbrockmendel

doc/source/whatsnew/v3.0.0.rst

@@ -707,6 +707,8 @@ Datetimelike
 - Bug in :meth:`to_datetime` with ``format="ISO8601"`` and ``utc=True`` where naive timestamps incorrectly inherited timezone offset from previous timestamps in a series. (:issue:`61389`)
 - Bug in :meth:`to_datetime` wrongly converts when ``arg`` is a ``np.datetime64`` object with unit of ``ps``. (:issue:`60341`)
 - Bug in setting scalar values with mismatched resolution into arrays with non-nanosecond ``datetime64``, ``timedelta64`` or :class:`DatetimeTZDtype` incorrectly truncating those scalars (:issue:`56410`)
+- Bug in constructing arrays with :class:`ArrowDtype` with ``timestamp`` type incorrectly allowing ``Decimal("NaN")`` (:issue:`??`)
+-
 
 Timedelta
 ^^^^^^^^^

pandas/core/arrays/arrow/array.py

@@ -500,6 +500,12 @@ def _box_pa_array(
                 value = to_timedelta(value, unit=pa_type.unit).as_unit(pa_type.unit)
                 value = value.to_numpy()
 
+            if pa_type is not None and pa.types.is_timestamp(pa_type):
+                # Use to_datetime to handle NaNs, disallow Decimal("NaN")
+                from pandas import to_datetime
+
+                value = to_datetime(value).as_unit(pa_type.unit)
+
             try:
                 pa_array = pa.array(value, type=pa_type, from_pandas=True)
             except (pa.ArrowInvalid, pa.ArrowTypeError):

pandas/tests/extension/test_arrow.py

@@ -3544,3 +3544,17 @@ def test_arrow_json_type():
     dtype = ArrowDtype(pa.json_(pa.string()))
     result = dtype.type
     assert result == str
+
+
+def test_timestamp_dtype_disallows_decimal():
+    # constructing with pyarrow timestamp dtype should disallow Decimal NaN,
+    # just like pd.to_datetime
+    vals = [pd.Timestamp("2016-01-02 03:04:05"), Decimal("NaN")]
+
+    msg = "<class 'decimal.Decimal'> is not convertible to datetime"
+    with pytest.raises(TypeError, match=msg):
+        # Check that the non-pyarrow version raises as expected
+        pd.to_datetime(vals)
+
+    with pytest.raises(TypeError, match=msg):
+        pd.array(vals, dtype=ArrowDtype(pa.timestamp("us")))

pandas/tests/io/test_sql.py

@@ -8,6 +8,7 @@
     time,
     timedelta,
 )
+from decimal import Decimal
 from io import StringIO
 from pathlib import Path
 import sqlite3
@@ -1038,6 +1039,11 @@ def test_dataframe_to_sql_arrow_dtypes(conn, request):
 def test_dataframe_to_sql_arrow_dtypes_missing(conn, request, nulls_fixture):
     # GH 52046
     pytest.importorskip("pyarrow")
+    if isinstance(nulls_fixture, Decimal):
+        pytest.skip(
+            reason="Decimal('NaN') not supported in constructor for timestamp dtype"
+        )
+
     df = DataFrame(
         {
             "datetime": pd.array(