可以使用'in‘关键字来过滤ListProperty(item_type=datetime.date)吗？

Question

我有谷歌应用程序引擎事件模型。我需要找到某个日期范围内的事件。可能是15.02.2012、15.03.2012、18.04.2013。但是当我搜索的时候，我得到了异常。

模型类：

class Event(db.Model):
    title = db.StringProperty()
    dates = db.ListProperty(item_type=datetime.date)

dates = [datetime.date.today(), datetime.date.today() + datetime.timedelta(days = 7), datetime.date.today() + datetime.timedelta(days = 14), datetime.date.today() + datetime.timedelta(days = 24)]

下面是我的问题：

# exception
query = db.GqlQuery('SELECT * FROM Event WHERE dates in :dates', dates=dates)

这段代码没有异常，但结果是错误的：

# 0 results, it's wrong
query = db.GqlQuery('SELECT * FROM Event WHERE dates in :dates', dates=[datetime.datetime.now()])

有效，但我需要“in”：

query = db.GqlQuery('SELECT * FROM Event WHERE dates = DATE(2012, 1, 23)')

同样的例外：

query = db.GqlQuery('SELECT * FROM Event WHERE dates in [DATE(2012, 1, 23)]')

异常描述：

ERROR    2012-01-23 13:38:28,335 base.py:117] error: code='internal_server_error', message="Unsupported type for property  : <type 'datetime.date'>"
ERROR    2012-01-23 13:38:28,345 base.py:119] Traceback (most recent call last):
  File "C:\Program Files (x86)\Google\google_appengine\lib\webapp2\webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "D:\project\eventinarea\eventinarea\handler\event.py", line 12, in get
    tags=self.param('tags')
  File "D:\project\eventinarea\eventinarea\logic\event.py", line 20, in search_events
    logging.info(query.count())
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\db\__init__.py", line 2059, in count
    raw_query = self._get_query()
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\db\__init__.py", line 2633, in _get_query
    self._cursor, self._end_cursor)
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\gql\__init__.py", line 326, in Bind
    query.update(enumerated_query)
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\datastore.py", line 1723, in update
    self.__setitem__(filter, value)
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\datastore.py", line 1666, in __setitem__
    datastore_types.ValidateProperty(' ', value, read_only=True)
  File "C:\Program Files (x86)\Google\google_appengine\google\appengine\api\datastore_types.py", line 1480, in ValidateProperty
    'Unsupported type for property %s: %s' % (name, v.__class__))
BadValueError: Unsupported type for property  : <type 'datetime.date'>

Answer 1

# 0 results, it's wrong 
query = db.GqlQuery('SELECT * FROM Event WHERE dates in :dates', dates=[datetime.datetime.now()]) 

这不会产生结果的原因是您传入了now() (包括年/月/日和小时/分/秒/微秒)，而实体的日期只是日期(年/月/日)。

下面这样的代码可能会起作用：

today = datetime.datetime.today()
today_date = datetime.datetime(year = today.year, month = today.month, day = today.day)
query = db.GqlQuery('SELECT * FROM Event WHERE dates in :dates', dates = [today_date]) 

我认为你的原始查询失败的原因是：

BadValueError: Unsupported type for property  : <type 'datetime.date'>

查询需要datetime.datetime对象，但您传入的是datetime.date对象。

下面这样的代码可能会起作用：

today = datetime.datetime.today()
today_date = datetime.datetime(year = today.year, month = today.month, day = today.day)
dates = [today_date, today_date + datetime.timedelta(days = 7), today_date + datetime.timedelta(days = 14), today_date + datetime.timedelta(days = 24)]
query = db.GqlQuery('SELECT * FROM Event WHERE dates in :dates', dates = dates)