Workaround for screwed up date values (#149)

* #143 Workaround for screwed up date values

- Adds constant FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE to return 0001-01-01

- Adds constant FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE to return 9999-12-31

- Add new unittests

* fix elif after return

Author: sti0

pyodata/v2/model.py

@@ -21,6 +21,8 @@
 from pyodata.exceptions import PyODataException, PyODataModelError, PyODataParserError
 
 LOGGER_NAME = 'pyodata.model'
+FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE = False
+FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE = False
 
 IdentifierInfo = collections.namedtuple('IdentifierInfo', 'namespace name')
 TypeInfo = collections.namedtuple('TypeInfo', 'namespace name is_collection')
@@ -414,8 +416,19 @@ 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, tzinfo=current_timezone()) + datetime.timedelta(milliseconds=int(value))
-        except ValueError:
-            raise PyODataModelError(f'Cannot decode datetime from value {value}.')
+        except (ValueError, OverflowError):
+            if FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE and int(value) < -62135596800000:
+                # Some service providers return false minimal date values.
+                # -62135596800000 is the lowest value PyOData could read.
+                # This workaroud fixes this issue and returns 0001-01-01 00:00:00+00:00 in such a case.
+                value = datetime.datetime(year=1, day=1, month=1, tzinfo=current_timezone())
+            elif FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE and int(value) > 253402300799999:
+                value = datetime.datetime(year=9999, day=31, month=12, tzinfo=current_timezone())
+            else:
+                raise PyODataModelError(f'Cannot decode datetime from value {value}. '
+                                        f'Possible value range: -62135596800000 to 253402300799999. '
+                                        f'You may fix this by setting `FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE` '
+                                        f' or `FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE` as a workaround.')
 
         return value
 

tests/test_model_v2.py

@@ -9,6 +9,7 @@
     PolicyIgnore, Config, PolicyFatal, NullType, NullAssociation, current_timezone, StructType
 from pyodata.exceptions import PyODataException, PyODataModelError, PyODataParserError
 from tests.conftest import assert_logging_policy
+import pyodata.v2.model
 
 
 def test_edmx(schema):
@@ -537,10 +538,20 @@ def test_traits_datetime():
     assert testdate.microsecond == 0
     assert testdate.tzinfo == current_timezone()
 
+    # parsing below lowest value with workaround
+    pyodata.v2.model.FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE = True
+    testdate = typ.traits.from_json("/Date(-62135596800001)/")
+    assert testdate.year == 1
+    assert testdate.month == 1
+    assert testdate.day == 1
+    assert testdate.tzinfo == current_timezone()
+
     # parsing the lowest value
-    with pytest.raises(OverflowError):
+    pyodata.v2.model.FIX_SCREWED_UP_MINIMAL_DATETIME_VALUE = False
+    with pytest.raises(PyODataModelError) as e_info:
         typ.traits.from_json("/Date(-62135596800001)/")
-
+    assert str(e_info.value).startswith('Cannot decode datetime from value -62135596800001.')
+       
     testdate = typ.traits.from_json("/Date(-62135596800000)/")
     assert testdate.year == 1
     assert testdate.month == 1
@@ -551,9 +562,19 @@ def test_traits_datetime():
     assert testdate.microsecond == 0
     assert testdate.tzinfo == current_timezone()
 
+    # parsing above highest value with workaround
+    pyodata.v2.model.FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE = True
+    testdate = typ.traits.from_json("/Date(253402300800000)/")
+    assert testdate.year == 9999
+    assert testdate.month == 12
+    assert testdate.day == 31
+    assert testdate.tzinfo == current_timezone()
+
     # parsing the highest value
-    with pytest.raises(OverflowError):
+    pyodata.v2.model.FIX_SCREWED_UP_MAXIMUM_DATETIME_VALUE = False
+    with pytest.raises(PyODataModelError) as e_info:
         typ.traits.from_json("/Date(253402300800000)/")
+    assert str(e_info.value).startswith('Cannot decode datetime from value 253402300800000.')
 
     testdate = typ.traits.from_json("/Date(253402300799999)/")
     assert testdate.year == 9999