How to move/rename object with overwritting in Zope? - plone

Question

I'm trying to move object (i.e. image file) from one folder to another one and then rename it - overwrite with existing object (i.e. updating file).
I'm doing it in Zope (I use Plone 4.2) in the following way:
from zope.component.hooks import getSite
from zope.traversing.api import traverse
site = getSite()
src = traverse(site, "preview/")
dst = traverse(site, "images/")
source = src.manage_cutObjects(ids=[previewName])
dst.manage_pasteObjects(source)
dst.manage_delObjects(ids=[existingName])
That piece of code does what it should do, it moves the object from one folder to another, then, as manage_renameObject procedure doesn't allow overwritting I delete the existing object which will be replaced. But if I add this line of code to achieve the final goal:
dst.manage_renameObject(previewName, existingName)
the exception is thrown, that ID provided by existingName is invalid (because the object with such ID already exists and no matter that I have deleted it before).
It looks like I need some commit or update to finalize object moving (or wait etc) but I can't find anything about that.
UPDATE
I forget to add: all changes (object moving, object deletion) before exception in manage_renameObject was thrown weren't applied. Now, with transaction.commit() (as proposed by lewicki) the changes are applied but exception still occurs. Procedure transaction.savepoint() didn't help much, the exception was still thrown and changes weren't applied.
RESOLVED
I was confused initially by the error message:
<CENTER>
('Empty or invalid id specified', u'27')
</CENTER>
When I tried to reproduce the issue in the ZMI I got:
<CENTER>
The id "27" is invalid - it is already in use.
</CENTER>
and I realized that I needed to look into the code.
I dig into the installed Plone code and then located what I looked for in eggs/Zope2-2.13.18-py2.7.egg/OFS/ObjectManager.py module, in checkValidId() procedure.. There was the root of all my problems:
if not id or not isinstance(id, str):
if isinstance(id, unicode):
id = escape(id)
raise BadRequest, ('Empty or invalid id specified', id)
so, I strict object names (IDs) to str type and it all became working...
Neither commit() nor savepoint() even was needed (but initially when I was figuring out the issue and observing in ZMI that my files was neither moved nor deleted that was confused me a lot).
Thank you for your assistance!

Answer 1

It's dst.manage_renameObject(oldid, newid). This should work
Documentation

Answer 2

Yes, you're right - commit may be requred. I had a similar problem and it was solved that way:
from zope.component.hooks import getSite
from zope.traversing.api import traverse
import transaction
site = getSite()
src = traverse(site, "preview/")
dst = traverse(site, "images/")
source = src.manage_cutObjects(ids=[newName])
dst.manage_pasteObjects(source)
dst.manage_delObjects(ids=[existingName])
transaction.commit()
Now I think that
transaction.savepoint()
should be enough but you have to check on your own.