Fix datetime handling while creating/updating entity

For most of EDM types, their value and json representation are the same.
One of the types with different behaviour is DateTime which is in json
in OData2 represented as "/Data(xxxx)/" instead of simply timestamp
xxxx. Thus, the need for 'to_json' function which for most data types
solely returns value. However, for DateTime, it returns a string in a
format mentioned above.

Reference links:

For literal format see "6. Primitive Data Types" at
https://www.odata.org/documentation/odata-version-2-0/overview/

For json format definition see "4. Primitive Types" at
https://www.odata.org/documentation/odata-version-2-0/json-format/

Author: mamiksik

pyodata/v2/model.py

@@ -322,6 +322,9 @@ def to_literal(self, value):
     def from_json(self, value):
         return value
 
+    def to_json(self, value):
+        return value
+
     def from_literal(self, value):
         return value
 
@@ -376,6 +379,14 @@ def to_literal(self, value):
 
         return super(EdmDateTimeTypTraits, self).to_literal(value.isoformat())
 
+    def to_json(self, value):
+        if isinstance(value, str):
+            return value
+
+        # Converts datetime into timestamp in milliseconds in UTC timezone as defined in ODATA specification
+        # https://www.odata.org/documentation/odata-version-2-0/json-format/
+        return f'/Date({int(value.replace(tzinfo=datetime.timezone.utc).timestamp()) * 1000})/'
+
     def from_json(self, value):
 
         if value is None:
@@ -389,7 +400,7 @@ def from_json(self, value):
 
         try:
             # https://stackoverflow.com/questions/36179914/timestamp-out-of-range-for-platform-localtime-gmtime-function
-            value = datetime.datetime(1970, 1, 1) + datetime.timedelta(milliseconds=int(value))
+            value = datetime.datetime(1970, 1, 1, tzinfo=datetime.timezone.utc) + datetime.timedelta(milliseconds=int(value))
         except ValueError:
             raise PyODataModelError('Cannot decode datetime from value {}.'.format(value))
 

pyodata/v2/service.py

@@ -455,7 +455,7 @@ def _build_values(entity_type, entity):
         values = {}
         for key, val in entity.items():
             try:
-                entity_type.proprty(key)
+                val = entity_type.proprty(key).typ.traits.to_json(val)
             except KeyError:
                 try:
                     nav_prop = entity_type.nav_proprty(key)
@@ -542,7 +542,7 @@ def set(self, **kwargs):
 
         for key, val in kwargs.items():
             try:
-                self._entity_type.proprty(key)
+                val = self._entity_type.proprty(key).typ.traits.to_json(val)
             except KeyError:
                 raise PyODataException(
                     'Property {} is not declared in {} entity type'.format(key, self._entity_type.name))

tests/test_service_v2.py

@@ -5,6 +5,7 @@
 import requests
 import pytest
 from unittest.mock import patch
+
 import pyodata.v2.model
 import pyodata.v2.service
 from pyodata.exceptions import PyODataException, HttpError, ExpressionError
@@ -277,7 +278,7 @@ def test_entity_key_complex(service):
     entity = service.entity_sets.TemperatureMeasurements.get_entity(key=None, **entity_key).execute()
     assert key_properties == set(entity_property.name for entity_property in  entity.entity_key.key_properties)
     # check also python represantation of date
-    assert entity.Date == datetime.datetime(2017, 12, 24, 18, 0)
+    assert entity.Date == datetime.datetime(2017, 12, 24, 18, 0, tzinfo=datetime.timezone.utc)
 
 
 def test_get_entity_property_complex_key(service):
@@ -574,7 +575,7 @@ def test_update_entity(service):
         "{0}/TemperatureMeasurements(Sensor='sensor1',Date=datetime'2017-12-24T18:00:00')".format(service.url),
         json={'d': {
             'Sensor': 'Sensor-address',
-            'Date': "datetime'2017-12-24T18:00'",
+            'Date': "/Date(1714138400000)/",
             'Value': 34
         }},
         status=204)
@@ -586,6 +587,16 @@ def test_update_entity(service):
     assert isinstance(request, pyodata.v2.service.EntityModifyRequest)
 
     request.set(Value=34)
+    # Tests if update entity correctly calls 'to_json' method
+    request.set(Date=datetime.datetime(2017, 12, 24, 19, 0))
+
+    assert request._values['Value'] == 34
+    assert request._values['Date'] == '/Date(1514142000000)/'
+
+    # If preformatted datetime is passed (e. g. you already replaced datetime instance with string which is
+    # complaint with odata specification), 'to_json' does not update given value (for backward compatibility reasons)
+    request.set(Date='/Date(1714138400000)/')
+    assert request._values['Date'] == '/Date(1714138400000)/'
 
     request.execute()
 
@@ -1418,3 +1429,82 @@ def test_navigation_count_with_filter(service):
     assert isinstance(request, pyodata.v2.service.GetEntitySetRequest)
 
     assert request.execute() == 3
+
+
+@responses.activate
+def test_create_entity_with_datetime(service):
+    """
+        Basic test on creating entity with datetime
+        Also tzinfo is set to simulate user passing datetime object with different timezone than UTC
+    """
+
+    # https://stackoverflow.com/questions/17976063/how-to-create-tzinfo-when-i-have-utc-offset
+    class MyUTCOffsetTimezone(datetime.tzinfo):
+
+        def __init__(self, offset=19800, name=None):
+            self.offset = datetime.timedelta(seconds=offset)
+            self.name = name or self.__class__.__name__
+
+        def utcoffset(self, dt):
+            return self.offset
+
+        def tzname(self, dt):
+            return self.name
+
+        def dst(self, dt):
+            return datetime.timedelta(0)
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.POST,
+        "{0}/TemperatureMeasurements".format(service.url),
+        headers={'Content-type': 'application/json'},
+        json={'d': {
+            'Sensor': 'Sensor1',
+            'Date': '/Date(1514138400000)/',
+            'Value': '34'
+        }},
+        status=201)
+
+
+    # Offset -18000 sec is for America/Chicago (CDT) timezone
+    request = service.entity_sets.TemperatureMeasurements.create_entity().set(**{
+        'Sensor': 'Sensor1',
+        'Date': datetime.datetime(2017, 12, 24, 18, 0, tzinfo=MyUTCOffsetTimezone(-18000)),
+        'Value': 34
+    })
+
+    assert request._values['Date'] == '/Date(1514138400000)/'
+
+    result = request.execute()
+    assert result.Date == datetime.datetime(2017, 12, 24, 18, 0, tzinfo=datetime.timezone.utc)
+
+
+@responses.activate
+def test_parsing_of_datetime_before_unix_time(service):
+    """Test DateTime handling of time before 1970"""
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.POST,
+        "{0}/TemperatureMeasurements".format(service.url),
+        headers={'Content-type': 'application/json'},
+        json={'d': {
+            'Sensor': 'Sensor1',
+            'Date': '/Date(-777877200000)/',
+            'Value': '34'
+        }},
+        status=201)
+
+    request = service.entity_sets.TemperatureMeasurements.create_entity().set(**{
+        'Sensor': 'Sensor1',
+        'Date': datetime.datetime(1945, 5, 8, 19, 0),
+        'Value': 34
+    })
+
+    assert request._values['Date'] == '/Date(-777877200000)/'
+
+    result = request.execute()
+    assert result.Date == datetime.datetime(1945, 5, 8, 19, 0, tzinfo=datetime.timezone.utc)