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Setting the modification date of an Archetype object in Plone.

Modification dates of Archetypes objects are set automatically to the current
date and time when an object is reindexed. Usually this is useful behaviour but if
,for example, you’re importing content from elsewhere into a Plone site and you’d
like to set the modification date to be some time in the past then it’s a problem.

Heres a method that sets the standard dates of an Archetypes content type ‘obj’
to DateTime ‘dt’.

def setObjDate(obj, dt):
    """Prevent update of modification date 
       during reindexing"""
    obj.setCreationDate(dt)
    obj.setEffectiveDate(dt)
    obj.setModificationDate(dt)
    od = obj.__dict__
    od['notifyModified'] = lambda *args: None
    obj.reindexObject()
    del od['notifyModified']

The trick, based on migration code found in the plone.app.blob package, is
to mask the ‘notifyModified’ class method with a no-op lambda on our
instance, call the reindex, then drop the mask so that the class method is visible
once again.

I’ve used this successfully for importing data into a Plone 4 instance but it should work at least as far back as Plone 2.5.