Converting _datetime_from_millis to handle microseconds.

Also making it require a float (or int) instead of bailing
out for NoneType. Changing the use of the method in
bigquery to not pass potentially null values and to multiply
by 1000.0 (convert from millis to micros). Also updating
micros -> datetime conversion in datastore to use the newly
converted method.

gcloud/_helpers.py

@@ -222,19 +222,16 @@ def _millis(when):
     return millis
 
 
-def _datetime_from_millis(value):
-    """Convert non-none timestamp to datetime, assuming UTC.
+def _datetime_from_microseconds(value):
+    """Convert timestamp to datetime, assuming UTC.
 
-    :rtype: :class:`datetime.datetime`, or ``NoneType``
+    :type value: float
+    :param value: The timestamp to convert
+
+    :rtype: :class:`datetime.datetime`
+    :returns: The datetime object created from the value.
     """
-    if value is not None:
-        # back-end returns timestamps as milliseconds since the epoch
-        seconds = int(value / 1000.0)
-        microseconds = 1000.0 * (value - 1000 * seconds)
-        return (
-            _EPOCH +
-            datetime.timedelta(seconds=seconds, microseconds=microseconds)
-        )
+    return _EPOCH + datetime.timedelta(microseconds=value)
 
 
 def _microseconds_from_datetime(value):

gcloud/bigquery/dataset.py

@@ -15,7 +15,7 @@
 """Define API Datasets."""
 import six
 
-from gcloud._helpers import _datetime_from_millis
+from gcloud._helpers import _datetime_from_microseconds
 from gcloud.exceptions import NotFound
 from gcloud.bigquery.table import Table
 
@@ -114,7 +114,10 @@ def created(self):
         :rtype: ``datetime.datetime``, or ``NoneType``
         :returns: the creation time (None until set from the server).
         """
-        return _datetime_from_millis(self._properties.get('creationTime'))
+        creation_time = self._properties.get('creationTime')
+        if creation_time is not None:
+            # creation_time will be in milliseconds.
+            return _datetime_from_microseconds(1000.0 * creation_time)
 
     @property
     def dataset_id(self):
@@ -141,7 +144,10 @@ def modified(self):
         :rtype: ``datetime.datetime``, or ``NoneType``
         :returns: the modification time (None until set from the server).
         """
-        return _datetime_from_millis(self._properties.get('lastModifiedTime'))
+        modified_time = self._properties.get('lastModifiedTime')
+        if modified_time is not None:
+            # modified_time will be in milliseconds.
+            return _datetime_from_microseconds(1000.0 * modified_time)
 
     @property
     def self_link(self):

gcloud/bigquery/table.py

@@ -18,7 +18,7 @@
 
 import six
 
-from gcloud._helpers import _datetime_from_millis
+from gcloud._helpers import _datetime_from_microseconds
 from gcloud._helpers import _millis_from_datetime
 from gcloud.exceptions import NotFound
 
@@ -116,7 +116,10 @@ def created(self):
         :rtype: ``datetime.datetime``, or ``NoneType``
         :returns: the creation time (None until set from the server).
         """
-        return _datetime_from_millis(self._properties.get('creationTime'))
+        creation_time = self._properties.get('creationTime')
+        if creation_time is not None:
+            # creation_time will be in milliseconds.
+            return _datetime_from_microseconds(1000.0 * creation_time)
 
     @property
     def etag(self):
@@ -134,7 +137,10 @@ def modified(self):
         :rtype: ``datetime.datetime``, or ``NoneType``
         :returns: the modification time (None until set from the server).
         """
-        return _datetime_from_millis(self._properties.get('lastModifiedTime'))
+        modified_time = self._properties.get('lastModifiedTime')
+        if modified_time is not None:
+            # modified_time will be in milliseconds.
+            return _datetime_from_microseconds(1000.0 * modified_time)
 
     @property
     def num_bytes(self):
@@ -212,7 +218,10 @@ def expires(self):
         :rtype: ``datetime.datetime``, or ``NoneType``
         :returns: the expiration time, or None
         """
-        return _datetime_from_millis(self._properties.get('expirationTime'))
+        expiration_time = self._properties.get('expirationTime')
+        if expiration_time is not None:
+            # expiration_time will be in milliseconds.
+            return _datetime_from_microseconds(1000.0 * expiration_time)
 
     @expires.setter
     def expires(self, value):
@@ -727,7 +736,8 @@ def _bool_from_json(value, field):
 
 def _datetime_from_json(value, field):
     if _not_null(value, field):
-        return _datetime_from_millis(float(value))
+        # Field value will be in milliseconds.
+        return _datetime_from_microseconds(1000.0 * float(value))
 
 
 def _record_from_json(value, field):

gcloud/datastore/helpers.py

@@ -22,7 +22,7 @@
 from google.protobuf.internal.type_checkers import Int64ValueChecker
 import six
 
-from gcloud._helpers import UTC
+from gcloud._helpers import _datetime_from_microseconds
 from gcloud._helpers import _microseconds_from_datetime
 from gcloud.datastore import _datastore_v1_pb2 as datastore_pb
 from gcloud.datastore.entity import Entity
@@ -224,9 +224,7 @@ def _get_value_from_value_pb(value_pb):
     result = None
     if value_pb.HasField('timestamp_microseconds_value'):
         microseconds = value_pb.timestamp_microseconds_value
-        naive = (datetime.datetime.utcfromtimestamp(0) +
-                 datetime.timedelta(microseconds=microseconds))
-        result = naive.replace(tzinfo=UTC)
+        result = _datetime_from_microseconds(microseconds)
 
     elif value_pb.HasField('key_value'):
         result = key_from_protobuf(value_pb.key_value)
@@ -285,7 +283,7 @@ def _set_protobuf_value(value_pb, val):
     :type value_pb: :class:`gcloud.datastore._datastore_v1_pb2.Value`
     :param value_pb: The value protobuf to which the value is being assigned.
 
-    :type val: `datetime.datetime`, boolean, float, integer, string,
+    :type val: :class:`datetime.datetime`, boolean, float, integer, string,
                :class:`gcloud.datastore.key.Key`,
                :class:`gcloud.datastore.entity.Entity`,
     :param val: The value to be assigned.

gcloud/test__helpers.py

@@ -334,25 +334,21 @@ def test_w_naive_datetime(self):
         self.assertEqual(result, MILLIS)
 
 
-class Test__datetime_from_millis(unittest2.TestCase):
+class Test__datetime_from_microseconds(unittest2.TestCase):
 
     def _callFUT(self, value):
-        from gcloud._helpers import _datetime_from_millis
-        return _datetime_from_millis(value)
+        from gcloud._helpers import _datetime_from_microseconds
+        return _datetime_from_microseconds(value)
 
-    def test_w_none(self):
-        self.assertTrue(self._callFUT(None) is None)
-
-    def test_w_millis(self):
+    def test_it(self):
         import datetime
         from gcloud._helpers import UTC
         from gcloud._helpers import _microseconds_from_datetime
 
         NOW = datetime.datetime(2015, 7, 29, 17, 45, 21, 123456,
                                 tzinfo=UTC)
         NOW_MICROS = _microseconds_from_datetime(NOW)
-        MILLIS = NOW_MICROS / 1000.0
-        self.assertEqual(self._callFUT(MILLIS), NOW)
+        self.assertEqual(self._callFUT(NOW_MICROS), NOW)
 
 
 class _AppIdentity(object):