[BUG-FIX] DataFrame created with tzinfo cannot use to_dict(orient="records")

Columns with datetimez are not returning arrays.

Closes #18372

Author: bolkedebruin

doc/source/whatsnew/v0.22.0.txt

@@ -108,7 +108,7 @@ Bug Fixes
 Conversion
 ^^^^^^^^^^
 
--
+- Bug in :func:`DataFrame.to_dict` where columns of datetimez where not arrays when used with ``orient='records'`` (:issue:`18372`)
 -
 -
 

pandas/core/frame.py

@@ -993,7 +993,7 @@ def to_dict(self, orient='dict', into=dict):
                           for k, v in compat.iteritems(self))
         elif orient.lower().startswith('r'):
             return [into_c((k, _maybe_box_datetimelike(v))
-                           for k, v in zip(self.columns, row))
+                           for k, v in zip(self.columns, np.atleast_1d(row)))
                     for row in self.values]
         elif orient.lower().startswith('i'):
             return into_c((k, v.to_dict(into)) for k, v in self.iterrows())

pandas/tests/tseries/test_timezones.py

@@ -882,6 +882,19 @@ def test_frame_reset_index(self):
         rs = roundtripped.index.tz
         assert xp == rs
 
+    def test_frame_to_dict_tz(self):
+        data = [(datetime.datetime(2017, 11, 18, 21, 53, 0, 219225,
+                                   tzinfo=pytz.utc),),
+                (datetime.datetime(2017, 11, 18, 22, 6, 30, 61810,
+                                   tzinfo=pytz.utc,),)]
+        df = DataFrame(list(data), columns=["datetime", ])
+
+        rec = df.to_dict(orient='records')
+        t1 = Timestamp('2017-11-18 21:53:00.219225+0000', tz=pytz.utc)
+        t2 = Timestamp('2017-11-18 22:06:30.061810+0000', tz=pytz.utc)
+        tm.assert_dict_equal(rec[0], {'data': t1})
+        tm.assert_dict_equal(rec[1], {'data': t2})
+
     def test_dateutil_tzoffset_support(self):
         values = [188.5, 328.25]
         tzinfo = tzoffset(None, 7200)