Hi,
This one is pretty high no the list of weirdest things to have happened
to me in a while. Basically, I have a persistent object that has an
empty __dict__() on the first request, until it suddenly decides to have
data again.
I'm on ZODB 3.9.3, using Zope 2.12 and Plone 4. I have a persistent
object, /plone/portal_registry:
class Registry(registry.Registry, SimpleItem):
pass
The base class is:
class Registry(Persistent):
def __init__(self):
self._records = Records(self)
Records is:
class Records(Persistent):
__parent__ = None
def __init__(self, parent):
self.__parent__ = parent
self.data = OOBTree()
def __getitem__(self, name):
return self.data.__getitem__(name)
The BTree contains string keys and Record objects as values. Record is:
class Record(Persistent):
__name__ = u""
__parent__ = None
field = None
__parent__ is set to records.__parent__, which is going to be the
Registry object.
field is set to a special persistent field class inheriting from
zope.schema's fields, but mixing in persistence. In this case, I have a
list field:
class PersistentField(persistent.Persistent):
"""Base class for persistent field definitions.
"""
class PersistentCollectionField(PersistentField,
zope.schema._field.AbstractCollection):
class List(PersistentCollectionField, zope.schema.List):
pass
I then have some code like this:
def cloneField(self, field):
clone = field.__class__.__new__(field.__class__)
clone.__dict__.update(field.__dict__)
for name, attr in field.__dict__.items():
if IField.providedBy(attr):
clone.__dict__[name] = self.cloneField(attr)
return clone
This is used like so:
registry = getUtility(IRegistry) # persistent/local
clone = self.cloneField(registry.records[recordName].field)
This seems to work always *except* on the first request immediately
after starting up Zope. In this case, field.__dict__ is {}. If I poke at
it long enough in pdb, it suddenly springs into life and contains values
again.
Can anyone enlighten me as to:
- why this may happen
- how I can ensure it stops happening :-)
Martin
--
Author of `Professional Plone Development`, a book for developers who
want to work with Plone. See http://martinaspeli.net/plone-book
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