handle error = ignore

Author: debnathshoham

pandas/core/tools/datetimes.py

@@ -500,7 +500,8 @@ def _to_datetime_with_format(
                 return _box_as_indexlike(result, utc=utc, name=name)
 
         # GH#42957 #replacing all na with np.nan
-        arg[isna(arg)] = np.nan
+        if errors != "ignore":
+            arg[isna(arg)] = np.nan
         # fallback
         res = _array_strptime_with_fallback(
             arg, name, tz, fmt, exact, errors, infer_datetime_format

pandas/tests/tools/test_to_datetime.py

@@ -199,6 +199,18 @@ def test_to_datetime_with_NA(self, data, format, expected):
         result = to_datetime(data, format=format)
         tm.assert_index_equal(result, expected)
 
+    def test_to_datetime_with_NA_and_errors(self):
+        # GH#42957
+        datelist = [pd.NA, 20210815, np.nan]
+        result = to_datetime(datelist, format="%Y%m", errors="ignore")
+        tm.assert_index_equal(result, Index(datelist))
+
+        result = to_datetime(datelist, format="%Y%m", errors="coerce")
+        tm.assert_index_equal(result, DatetimeIndex(["NaT", "NaT", "NaT"]))
+
+        with pytest.raises(ValueError, match="unconverted data remains"):
+            to_datetime(datelist, format="%Y%m", errors="raise")
+
     @pytest.mark.parametrize("cache", [True, False])
     def test_to_datetime_format_integer(self, cache):
         # GH 10178