add support for If-Unmodified-Since conditional PUT requests

tests/base.py

@@ -7,13 +7,15 @@
 from sqlalchemy.orm import scoped_session, sessionmaker, relationship
 from sqlalchemy.ext.declarative import declarative_base
 from datetime import datetime
+from webob import UTC
 
 maker = sessionmaker(autoflush=True, autocommit=False,
  extension=ZopeTransactionExtension())
 DBSession = scoped_session(maker)
 DeclarativeBase = declarative_base()
 metadata = DeclarativeBase.metadata
 
+MODIFICATION_DATE = datetime(2010, 1, 1, 12, 0, tzinfo=UTC)
 
 class Genre(DeclarativeBase):
  __tablename__ = "genres"
@@ -33,6 +35,9 @@ class Movie(DeclarativeBase):
  genre_id = Column(Integer, ForeignKey(Genre.genre_id), nullable=True)
  genre = relationship(Genre)
 
+ @property
+ def updated_at(self):
+ return MODIFICATION_DATE
 
 class Actor(DeclarativeBase):
  __tablename__ = "actors"

tests/test_rest_json.py

@@ -1,6 +1,7 @@
 from tg import TGController
 from tgext.crud import EasyCrudRestController
-from .base import CrudTest, Movie, DBSession, metadata, Genre, Actor
+from .base import CrudTest, Movie, DBSession, metadata, Genre, Actor, MODIFICATION_DATE
+from webob import serialize_date
 
 import transaction
 
@@ -131,7 +132,7 @@ def test_delete_nofilter(self):
 
 class TestRestJsonRead(CrudTest):
  """Basic tests for GET requests with JSON responses"""
- 
+
  def controller_factory(self):
  class MovieController(EasyCrudRestController):
  model = Movie
@@ -377,3 +378,48 @@ def test_put_relationship(self):
  assert len(result.json['value']['actors']) == 2, result
 
  assert DBSession.query(Actor).filter_by(movie_id=movie['movie_id']).count() == 2
+
+class TestRestJsonConditionalPut(CrudTest):
+ def controller_factory(self):
+ class MovieController(EasyCrudRestController):
+ model = Movie
+ conditional_update_field = 'updated_at'
+
+ class RestJsonController(TGController):
+ movies = MovieController(DBSession)
+
+ return RestJsonController()
+
+ def test_put_failed(self):
+ result = self.app.post_json('/movies.json', params={'title':'Movie Test'})
+ movie = result.json['value']
+ assert result.last_modified == MODIFICATION_DATE
+
+ previous_date = MODIFICATION_DATE.replace(year=result.last_modified.year-1)
+ result = self.app.put_json('/movies/%s.json' % movie['movie_id'], status=412,
+ headers=[('If-Unmodified-Since', serialize_date(previous_date))],
+ params={'title':'New Title'})
+ assert result.json['value']['title'] == 'Movie Test'
+
+ def test_put(self):
+ result = self.app.post_json('/movies.json', params={'title':'Movie Test'})
+ movie = result.json['value']
+ assert result.last_modified == MODIFICATION_DATE
+
+ previous_date = MODIFICATION_DATE.replace(year=result.last_modified.year+1)
+ result = self.app.put_json('/movies/%s.json' % movie['movie_id'], status=200,
+ headers=[('If-Unmodified-Since', serialize_date(previous_date))],
+ params={'title':'New Title'})
+ assert result.json['value']['title'] == 'New Title'
+
+ def test_get_one(self):
+ result = self.app.post_json('/movies.json', params={'title':'Movie Test'})
+ orig_movie = result.json['value']
+
+ result = self.app.get('/movies/%s.json' % orig_movie['movie_id'])
+ assert result.last_modified == MODIFICATION_DATE
+
+ movie = result.json
+ assert movie['model'] == 'Movie', result
+ assert movie['value']['title'] == orig_movie['title']
+ assert movie['value']['movie_id'] == orig_movie['movie_id']

tgext/crud/controller.py

@@ -81,6 +81,7 @@ class CrudRestController(RestController):
  substring_filters = []
  search_fields = True # True for automagic
  json_dictify = False # True is slower but provides relations
+ conditional_update_field = None
  pagination = {'items_per_page': 7}
  style = Markup('''
 #menu_items {
@@ -306,6 +307,9 @@ def get_one(self, *args, **kw):
  obj = self.provider.get_obj(self.model, kw)
  if obj is None:
  tg.response.status_code = 404
+ elif self.conditional_update_field is not None:
+ tg.response.last_modified = getattr(obj, self.conditional_update_field)
+
  return dict(model=self.model.__name__,
  value=self._dictify(obj))
 
@@ -344,6 +348,9 @@ def post(self, *args, **kw):
  obj = self.provider.create(self.model, params=kw)
 
  if tg.request.response_type == 'application/json':
+ if obj is not None and self.conditional_update_field is not None:
+ tg.response.last_modified = getattr(obj, self.conditional_update_field)
+
  return dict(model=self.model.__name__,
  value=self._dictify(obj))
 
@@ -368,12 +375,24 @@ def put(self, *args, **kw):
 
  obj = self.provider.get_obj(self.model, kw)
 
- if obj is not None:
+ #This should actually by done by provider.update to make it atomic
+ can_modify = True
+ if obj is not None and self.conditional_update_field is not None and \
+ tg.request.if_unmodified_since is not None and \
+ tg.request.if_unmodified_since < getattr(obj, self.conditional_update_field):
+ can_modify = False
+
+ if obj is not None and can_modify:
  obj = self.provider.update(self.model, params=kw, omit_fields=omit_fields)
 
  if tg.request.response_type == 'application/json':
  if obj is None:
  tg.response.status_code = 404
+ elif can_modify is False:
+ tg.response.status_code = 412
+ elif self.conditional_update_field is not None:
+ tg.response.last_modified = getattr(obj, self.conditional_update_field)
+
  return dict(model=self.model.__name__,
  value=self._dictify(obj))