appengine: ReferencePropertyResolveError: ReferenceProperty failed to be resolved: [u'User', xxxxxxxxxxxxx]
appengine: ReferencePropertyResolveError: ReferenceProperty failed to be resolved: [u'User', xxxxxxxxxxxxx]
我有获取参与者并显示他们的代码。控制视图的逻辑如下：
def fetch_participants(self, count=12):
memcache_key = 'mission_participants:%d:%d' % (self.key().id(), count)
participants = utils.deserialize_entities(memcache.get(memcache_key))
if participants is None:
participants = self.fetch_participants_datastore(count)
memcache.set(memcache_key, utils.serialize_entities(participants), 3600)
return participants
问题是 appengine 抛出以下错误：
File "site/templates/participant_base.html", line 209, in block "content"
{% set participants = mission.fetch_participants(40) %}
File "/base/data/home/apps/proj/32.424491487021355902/models/mission.py", line 311, in fetch_participants
participants = self.fetch_participants_datastore(count)
File "/base/data/home/apps/proj/32.424491487021355902/models/mission.py", line 301, in fetch_participants_datastore
users = [join.user for join in joins]
File "/base/alloc/tmpfs/dynamic_runtimes/python27g/9fae800fb98bd45d/python27/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 3734, in __get__
reference_id.to_path())
ReferencePropertyResolveError: ReferenceProperty failed to be resolved: [u'User', xxxxxxxxxxx]
错误似乎是这一行：
participants = self.fetch_participants_datastore(count)
Whosebug 上的一位用户提出了类似的问题：
This happens when you attempt to resolve a reference property (by
dereferencing it - for instance, (MyModel.MyReferenceProp.foo), and
the property being referenced no longer exists - because it has been
deleted.
You need to modify your code to catch this exception when you
dereference an entity that may have been deleted, and handle it
appropriately.
我想我必须做类似的事情，问题是我不知道如何修改代码来捕获异常。您是否可以过滤参与者以不包括引用的参与者？有更好的选择吗？
def fetch_participants_datastore(self, count=12):
joins = self.mission_joins.order('-created').fetch(count * 2)
utils.prefetch_refprops(joins, MissionJoin.user)
users = [join.user for join in joins]
with_avatars = [user for user in users if user.has_avatar()]
without_avatars = [user for user in users if not user.has_avatar()]
users = with_avatars + without_avatars
return users[:count]
编辑：
for join in joins:
try:
users = join.user
except:
pass
将代码的第 301 行打断为一个 for 循环，并在包含 join.user
的行周围添加一个 try/except 块
我有获取参与者并显示他们的代码。控制视图的逻辑如下：
def fetch_participants(self, count=12):
memcache_key = 'mission_participants:%d:%d' % (self.key().id(), count)
participants = utils.deserialize_entities(memcache.get(memcache_key))
if participants is None:
participants = self.fetch_participants_datastore(count)
memcache.set(memcache_key, utils.serialize_entities(participants), 3600)
return participants
问题是 appengine 抛出以下错误：
File "site/templates/participant_base.html", line 209, in block "content"
{% set participants = mission.fetch_participants(40) %}
File "/base/data/home/apps/proj/32.424491487021355902/models/mission.py", line 311, in fetch_participants
participants = self.fetch_participants_datastore(count)
File "/base/data/home/apps/proj/32.424491487021355902/models/mission.py", line 301, in fetch_participants_datastore
users = [join.user for join in joins]
File "/base/alloc/tmpfs/dynamic_runtimes/python27g/9fae800fb98bd45d/python27/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 3734, in __get__
reference_id.to_path())
ReferencePropertyResolveError: ReferenceProperty failed to be resolved: [u'User', xxxxxxxxxxx]
错误似乎是这一行：
participants = self.fetch_participants_datastore(count)
Whosebug 上的一位用户提出了类似的问题：
This happens when you attempt to resolve a reference property (by dereferencing it - for instance, (MyModel.MyReferenceProp.foo), and the property being referenced no longer exists - because it has been deleted.
You need to modify your code to catch this exception when you dereference an entity that may have been deleted, and handle it appropriately.
我想我必须做类似的事情，问题是我不知道如何修改代码来捕获异常。您是否可以过滤参与者以不包括引用的参与者？有更好的选择吗？
def fetch_participants_datastore(self, count=12):
joins = self.mission_joins.order('-created').fetch(count * 2)
utils.prefetch_refprops(joins, MissionJoin.user)
users = [join.user for join in joins]
with_avatars = [user for user in users if user.has_avatar()]
without_avatars = [user for user in users if not user.has_avatar()]
users = with_avatars + without_avatars
return users[:count]
编辑：
for join in joins:
try:
users = join.user
except:
pass
将代码的第 301 行打断为一个 for 循环，并在包含 join.user
的行周围添加一个 try/except 块