[Zope] Re: Appending to a file via manage_edit?

Andreas Jung lists at zopyx.com
Tue Dec 11 12:37:49 EST 2007

--On 11. Dezember 2007 18:33:14 +0100 Josef Meile <jmeile at hotmail.com> 

>>> I've been looking around for this, but can't seem to find anything.  I'm
>>> assuming that it is just not possible, but thought I'd ask just in case.
>>> For File objects, I see that manage_edit() has the parameters: title,
>>> content_type, precondition, filedata & REQUEST.  Setting something in
>>> the filedata parameter will replace the file's current data with that.
>>> This implies (to me at least) that the only way one can edit a file is a
>>> complete rewrite.  Does there exist a way to simply append data to the
>>> end
>>> of the file?  For instance, if one wanted to write to a file line by
>>> line,
>>> is that possible in Zope?
>> out-of-the-box: NO
>> Appending data would require the manipulation of the linked list of Pdata
>> elements. There is no API for this available...so basically forget it.
> What about the python pickle/cpickle and marshal modules? If I'm not
> wrong zope uses cpickle to append data to the Data.fs, or am I wrong?
> I haven't read the module documetation deeply, but as I understand,
> pickle/cpickle is used for serializing python objects, while marshal is
> for binary data.
> http://docs.python.org/lib/module-pickle.html
> http://docs.python.org/lib/module-marshal.html
> Anyway, you still need to load the whole file into a temporal memory.

Completely unrelated at this point. You can only update a file as a whole
with the existing functionality. You are of course free to write your own
file implementation.

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