Refresh SQLAlchemy object after creation in POST

Author: jfinkels

CHANGES

@@ -48,6 +48,10 @@ Not yet released.
 - :issue:`599`: fixes `unicode` bug using :func:`!urlparse.urljoin` with the
   `future`_ library in resource serialization.
 - :issue:`625`: adds schema metadata to root endpoint.
+- :issue:`630`: correctly respond with timezone-naive :class:`datetime`
+  attributes on :http:method:`post` requests when the database doesn't support
+  timezones, even if the request included a timezone-aware :class:`datetime`
+  attribute.
 
 .. _future: http://python-future.org/
 

flask_restless/views/resources.py

@@ -478,6 +478,19 @@ def post(self):
         except self.validation_exceptions as exception:
             return self._handle_validation_exception(exception)
         only = self.sparse_fields.get(self.collection_name)
+        # Refresh the instance's attributes/relationships from the database.
+        #
+        # One place where we need this is when the request has a
+        # timezone-aware datetime attribute. In this case, the
+        # deserialized SQLAlchemy object actually seems to have the
+        # timezone-aware datetime attribute regardless of whether the
+        # underlying database has support for it. When added to the
+        # database however, the timezone is (silently) dropped if the
+        # database does not support it. By refreshing the object, we
+        # force the attribute to be reloaded from the database, thereby
+        # reloading a timezone-naive attribute into the SQLAlchemy
+        # object.
+        self.session.refresh(instance)
         # Get the dictionary representation of the new instance as it
         # appears in the database.
         try:

tests/test_creating.py

@@ -20,6 +20,8 @@
 
 """
 from __future__ import division
+from datetime import timedelta
+from datetime import timezone
 from datetime import datetime
 
 import dateutil
@@ -77,7 +79,7 @@ class Person(self.Base):
             id = Column(Integer, primary_key=True)
             age = Column(Integer)
             name = Column(Unicode, unique=True)
-            birth_datetime = Column(DateTime, nullable=True)
+            birth_datetime = Column(DateTime(timezone=False), nullable=True)
             bedtime = Column(Time)
             hangtime = Column(Interval)
             articles = relationship('Article')
@@ -885,6 +887,35 @@ def test_special_field_names(self):
         assert article['type'] == 'article'
         assert article['attributes']['type'] == u'fluff'
 
+    def test_timezone_aware_datetime(self):
+        """A timezone dropped by the DB should be reflected in the response.
+
+        For more information, see GitHub issue #630.
+
+        """
+        # Request to create a person with a timezone-aware datetime attribute.
+        tz = timezone(timedelta(hours=-5))
+        now = datetime.now(tz=tz)
+        data = {
+            'data': {
+                'type': 'person',
+                'attributes': {
+                    'birth_datetime': now.isoformat()
+                }
+            }
+        }
+        response = self.app.post('/api/person', data=dumps(data))
+        self.assertEqual(response.status_code, 201)
+        document = loads(response.data)
+        person = document['data']
+        birth_datetime = person['attributes']['birth_datetime']
+        birth_datetime = dateutil.parser.parse(birth_datetime)
+        # Our request had a timezone-aware attribute, but the database
+        # is timezone-naive so we expect that the database created a
+        # timezone-naive object. The returned resource should reflect
+        # that timezone-naive object.
+        self.assertEqual(birth_datetime, now.replace(tzinfo=None))
+
 
 class TestProcessors(ManagerTestBase):
     """Tests for pre- and postprocessors."""

tests/test_updating.py

@@ -21,7 +21,8 @@
 from __future__ import division
 
 from datetime import datetime
-from unittest2 import skip
+from datetime import timedelta
+from datetime import timezone
 
 try:
     from flask_sqlalchemy import SQLAlchemy
@@ -37,7 +38,6 @@
 from sqlalchemy import Integer
 from sqlalchemy import Time
 from sqlalchemy import Unicode
-from sqlalchemy.ext.associationproxy import association_proxy
 from sqlalchemy.ext.hybrid import hybrid_property
 from sqlalchemy.orm import backref
 from sqlalchemy.orm import relationship
@@ -82,7 +82,7 @@ class Person(self.Base):
             name = Column(Unicode, unique=True)
             bedtime = Column(Time)
             date_created = Column(Date)
-            birth_datetime = Column(DateTime)
+            birth_datetime = Column(DateTime(timezone=False))
 
             def foo(self):
                 return u'foo'
@@ -961,6 +961,37 @@ def test_integer_id_error_message(self):
         check_sole_error(response, 409, ['"id" element', 'resource object',
                                          'must be a JSON string'])
 
+    def test_timezone_aware_datetime(self):
+        """Test that timezone information is correctly dropped.
+
+        For more information, see GitHub issue #630.
+
+        """
+        # Create a person with a timezone-naive datetime attribute.
+        now = datetime.now()
+        person = self.Person(id=1, birth_datetime=now)
+        self.session.add(person)
+        self.session.commit()
+        # Request to update the attribute with a timezone-aware datetime.
+        tz = timezone(timedelta(hours=-5))
+        later = datetime.now(tz=tz)
+        data = {
+            'data': {
+                'id': '1',
+                'type': 'person',
+                'attributes': {
+                    'birth_datetime': later.isoformat()
+                }
+            }
+        }
+        response = self.app.patch('/api/person/1', data=dumps(data))
+        self.assertEqual(response.status_code, 204)
+        # Our request had a timezone-aware attribute, but the database
+        # is timezone-naive so we expect that the database created a
+        # timezone-naive object. The returned resource should reflect
+        # that timezone-naive object.
+        self.assertEqual(person.birth_datetime, later.replace(tzinfo=None))
+
 
 class TestProcessors(ManagerTestBase):
     """Tests for pre- and postprocessors."""