raise error on unsafe decimal parse with pyarrow types

pandas/core/arrays/arrow/array.py

@@ -527,11 +527,7 @@ def _box_pa_array(
  else:
  try:
  pa_array = pa_array.cast(pa_type)
- except (
- pa.ArrowInvalid,
- pa.ArrowTypeError,
- pa.ArrowNotImplementedError,
- ):
+ except (pa.ArrowNotImplementedError, pa.ArrowTypeError):
  if pa.types.is_string(pa_array.type) or pa.types.is_large_string(
  pa_array.type
  ):

pandas/tests/extension/test_arrow.py

@@ -3203,6 +3203,30 @@ def test_pow_missing_operand():
  tm.assert_series_equal(result, expected)
 
 
+@pytest.mark.skipif(
+ pa_version_under11p0, reason="Decimal128 to string cast implemented in pyarrow 11"
+)
+def test_decimal_parse_raises():
+ # GH 56984
+ ser = pd.Series(["1.2345"], dtype=ArrowDtype(pa.string()))
+ with pytest.raises(
+ pa.lib.ArrowInvalid, match="Rescaling Decimal128 value would cause data loss"
+ ):
+ ser.astype(ArrowDtype(pa.decimal128(1, 0)))
+
+
+@pytest.mark.skipif(
+ pa_version_under11p0, reason="Decimal128 to string cast implemented in pyarrow 11"
+)
+def test_decimal_parse_succeeds():
+ # GH 56984
+ ser = pd.Series(["1.2345"], dtype=ArrowDtype(pa.string()))
+ dtype = ArrowDtype(pa.decimal128(5, 4))
+ result = ser.astype(dtype)
+ expected = pd.Series([Decimal("1.2345")], dtype=dtype)
+ tm.assert_series_equal(result, expected)
+
+
 @pytest.mark.parametrize("pa_type", tm.TIMEDELTA_PYARROW_DTYPES)
 def test_duration_fillna_numpy(pa_type):
  # GH 54707