model: fix edge case for Edm.DateTimeOffset.from_json() without offset (#232)

We were expecting that the offset part is mandatory and that the service should return /Date(1659430517461+0000)/ for offset set to UTC. Unable confirm in odata.org and W3C specifications, but some services works for this Edm type as offset is not mandatory of UTC timezone.

Now, if the offset part is missing in incoming JSON payload, it should work as if +0000 was provided.

FIXES #231

Author: phanak-sap

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+- model: fix edge case for Edm.DateTimeOffset.from_json() without offset - Petr Hanak
+
 ## [1.10.0]
 
 ### Added

pyodata/v2/model.py

@@ -529,6 +529,12 @@ def to_json(self, value):
         return f'/Date({ticks}{offset_in_minutes:+05})/'
 
     def from_json(self, value):
+        # special edge case:
+        # datetimeoffset'yyyy-mm-ddThh:mm[:ss]' = defaults to UTC, when offset value is not provided in responde data by service but the metadata is EdmDateTimeOffset
+        # intentionally just for from_json, generation of to_json should always provide timezone info
+        if re.match(r"^/Date\((?P<milliseconds_since_epoch>-?\d+)\)/$", value):
+            value = value.replace(')', '+0000)')
+
         matches = re.match(r"^/Date\((?P<milliseconds_since_epoch>-?\d+)(?P<offset_in_minutes>[+-]\d+)\)/$", value)
         try:
             milliseconds_since_epoch = matches.group('milliseconds_since_epoch')

tests/test_model_v2.py

@@ -690,6 +690,9 @@ def test_traits_datetimeoffset(type_date_time_offset):
 def test_traits_datetimeoffset_to_literal(type_date_time_offset):
     """Test Edm.DateTimeOffset trait: Python -> literal"""
 
+    testdate = datetime(1, 1, 1, 0, 0, 0, 0, tzinfo=timezone.utc)
+    assert type_date_time_offset.traits.to_literal(testdate) == "datetimeoffset'0001-01-01T00:00:00+00:00'"
+
     testdate = datetime(2005, 1, 28, 18, 30, 44, 123456, tzinfo=timezone(timedelta(hours=3, minutes=40)))
     assert type_date_time_offset.traits.to_literal(testdate) == "datetimeoffset'2005-01-28T18:30:44.123456+03:40'"
 
@@ -746,7 +749,7 @@ def test_traits_datetimeoffset_from_invalid_literal(type_date_time_offset):
     assert str(e_info.value).startswith('Cannot decode datetimeoffset from value xyz')
 
 
-def test_traits_datetimeoffset_from_odata(type_date_time_offset):
+def test_traits_datetimeoffset_from_json(type_date_time_offset):
     """Test Edm.DateTimeOffset trait: OData -> Python"""
 
     # parsing full representation
@@ -768,6 +771,14 @@ def test_traits_datetimeoffset_from_odata(type_date_time_offset):
     assert testdate.microsecond == 0
     assert testdate.tzinfo == timezone(-timedelta(minutes=5))
 
+    # parsing special edge case with no offset provided, defaults to UTC
+    testdate = type_date_time_offset.traits.from_json("/Date(217567986000)/")
+    assert testdate.year == 1976
+    assert testdate.minute == 33
+    assert testdate.second == 6
+    assert testdate.microsecond == 0
+    assert testdate.tzinfo == timezone.utc
+
     # parsing below lowest value with workaround
     pyodata.v2.model.FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE = True
     testdate = type_date_time_offset.traits.from_json("/Date(-62135596800001+0001)/")