在使用 MongoAlchemy 时，我一直在努力解决一个奇怪的错误。
我的模型name = db.StringField()上有一个。Participant大多数情况下它工作正常，但由于某种原因，该字段偶尔会被QueryField. 如果我从模块中重新加载我的Participant课程，它会在一段时间内正常工作，但随后又会中断。
这是发生这种情况的终端会话：
In [99]: from webapp.models import *
In [100]: Participant.by_name('yaronTesting') # My own method, which filters by name
Out[100]: <Participant yaronTesting>
In [101]: Participant.query.all()
Out[101]: [<Participant name>, <Participant name>]
# What?
In [102]: Participant.query.all()[0]
Out[102]: <Participant name>
In [103]: Participant.query.all()[0].name
Out[103]: QueryField(name)
In [104]: from webapp.models import Participant
In [105]: Participant.query.all()
Out[105]: [<Participant yaronTesting>, <Participant tsviki>]
In [106]: Participant.query.all()[0].name
Out[106]: u'yaronTesting'
我是 MongoDB 的新手，对于将其投入生产非常紧张——有谁知道幕后可能会发生什么？
因此，为了回应 Jeff 的评论，我有另一个会话，问题发生在查询之外：
In [168]: tsviki_old
Out[168]: <Participant name>
In [169]: tsviki_old.mongo_id
Out[169]: ObjectId('53f4f27a6c4dae23aba41419')
In [170]: tsviki_new = Participant.by_name('tsviki')
Out[170]: <Participant tsviki>
In [171]: tsviki_new.mongo_id
Out[171]: ObjectId('53f4f27a6c4dae23aba41419')
In [172]: tsviki_old.mongo_id
Out[172]: ObjectId('53f4f27a6c4dae23aba41419')
In [173]: tsviki_old
Out[173]: <Participant name>
In [174]: tsviki_new
Out[174]: <Participant tsviki>
In [175]: tsviki_old.name
Out[175]: QueryField(name)
In [176]: tsviki_new.name
Out[176]: u'tsviki'
In [179]: tsviki_old.created
Out[179]: QueryField(created)
In [180]: tsviki_old.modified
Out[180]: QueryField(modified)
In [181]: tsviki_old.sessions
Out[181]: QueryField(sessions)
# It happened again! To tsviki_new!
In [182]: tsviki_new.created
Out[182]: QueryField(created)
In [183]: tsviki_new
Out[183]: <Participant name>
In [184]: tsviki_new.name
Out[184]: QueryField(name)
In [185]: tsviki_new.mongo_id
Out[185]: ObjectId('53f4f27a6c4dae23aba41419')
我不记得在最后一次会议上做任何其他事情，除了可能在某个时候保存文件。似乎有一些与时间相关的组件——如果我离开解释器一段时间然后回来，通常会发生这种情况，但是我无法确定导致这种情况的特定行为。
另外，仅供参考：
@classmethod
def by_name(cls, name):
return Participant.query.filter({'name': name}).first()
最后，当我将name字段添加到__init__函数并尝试实例化一些对象时，出现以下错误（早期版本未向 init 传递任何参数）：
In [36]: Participant.query.all()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-36-310f11265a76> in <module>()
----> 1 Participant.query.all()
/Users/kronosapiens/Dropbox/Documents/Development/code/environments/pm/lib/python2.7/site-packages/mongoalchemy/query.pyc in all(self)
177 def all(self):
178 ''' Return all of the results of a query in a list'''
--> 179 return [obj for obj in iter(self)]
180
181 def distinct(self, key):
/Users/kronosapiens/Dropbox/Documents/Development/code/environments/pm/lib/python2.7/site-packages/mongoalchemy/query.pyc in next(self)
410
411 def next(self):
--> 412 return self._next_internal()
413 __next__ = next
414
/Users/kronosapiens/Dropbox/Documents/Development/code/environments/pm/lib/python2.7/site-packages/mongoalchemy/query.pyc in _next_internal(self)
421 if obj:
422 return obj
--> 423 value = self.session._unwrap(self.type, value, fields=self.fields)
424 if not isinstance(value, dict):
425 self.session.cache_write(value)
/Users/kronosapiens/Dropbox/Documents/Development/code/environments/pm/lib/python2.7/site-packages/mongoalchemy/session.pyc in _unwrap(self, type, obj, **kwargs)
333 def _unwrap(self, type, obj, **kwargs):
334 obj = type.transform_incoming(obj, session=self)
--> 335 return type.unwrap(obj, session=self, **kwargs)
336
337 @property
/Users/kronosapiens/Dropbox/Documents/Development/code/environments/pm/lib/python2.7/site-packages/mongoalchemy/document.pyc in unwrap(cls, obj, fields, session)
494 if fields is not None:
495 params['retrieved_fields'] = fields
--> 496 obj = cls(loading_from_db=True, **params)
497 obj._mark_clean()
498 obj._session = session
/Users/kronosapiens/Dropbox/Documents/Development/code/jobs/paragon/webapp/webapp/models.py in __init__(self, name, **kwargs)
319
320 def __init__(self, name, **kwargs):
--> 321 super(Participant, self).__init__(
322 name=name,
323 **kwargs)
TypeError: super(type, obj): obj must be an instance or subtype of type