I have some buried-in-the-codebase-since-0.7 upsert code that uses `merge`.
In order to avoid certain attributes from being used in the merge
comparison, the attributes were deleted using delattr..
The code looks something like this:
db_obj = sess.query(obj_type).filter_by(**filters).one()
pk = obj.__mapper__.primary_key[0].name
setattr(obj, pk, getattr(db_obj, pk)) #convince merge they're comparable
for attr in merge_ignores:
#See http://goo.gl/oBbpp for why we delete the attribute to avoid
comparison
delattr(obj, attr)
obj = sess.merge(obj)
I've recently been trying 1.0.0b4, and now 1.0.0b5 and this code no longer
works.
Specifically, the code throws a KeyError on the delattr line. Here's the
clipped traceback:
File
"/home/russ/code/bitbucket/sqlalchemy/lib/sqlalchemy/orm/attributes.py",
line 227, in __delete__
self.impl.delete(instance_state(instance), instance_dict(instance))
File
"/home/russ/code/bitbucket/sqlalchemy/lib/sqlalchemy/orm/attributes.py",
line 738, in delete
del dict_[self.key]
KeyError: 'date_added_log'
The attribute *definitely* exists at the time (albeit with a value of
`None`, but it's there). I doubt it matters, but obj is an instance of
declarative_base'd class.
I see that __slots__ has been introduced to `ScalarObjectAttributeImpl`,
which is where the is tanking. __slots__ seems like a likely candidate
here, but I have to dig further.
For now I've reverted back to 0.9.9 so the code works again.
Is there some less sketchy way (that works in 1.0!) to force merge to not
look at certain fields?
Russ
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