[Zope] finding the modification time

[Robin Becker]

In article <tj067EAKdOx3Ewqq@jessikat.demon.co.uk>, Robin Becker
<robin@jessikat.demon.co.uk> writes
>In article <37C4821E.81BC6BAA@digicool.com>, Jim Fulton
><jim@digicool.com> writes
>>Robin Becker wrote:
>>> 
>>> can any one tell me what's the easiest way to find the mdoification date
>>> of an object in python.
>>
>>  o._p_mtime
>>
>>gives the modification time as a time.time.
>>
>...
>thanks
I tried the following

def make_image(self,id='anImage'):
    self=self.this().tmp
    try:
        self.manage_delObjects([id])
    except:
        pass
    self.manage_addImage(id,ImageClock(None))
    I=self[id]
    I.content_type='image/gif'
    return str(I._p_mtime))

and it always returns 'None' is this because the object transaction
isn't yet committed?
-- 
Robin Becker