On 12/15/2011 1:31 PM, Michael Bayer wrote:
Are there reasons one need to avoid referencing unloaded relationships from
within before_upate()? (I can't recall the exact problem I've had in the past
with that at the moment.)
Thanks for all the input. Regarding the issue of referencing a
relationship from within before_update()/before_insert(), etc. I looked
up my previous problem and it is related to this code from strategies.py:
class LazyLoader()
...
def _load_for_state(self, state, passive):
...
if self.use_get:
if session._flushing:
get_attr =
instance_mapper._get_committed_state_attr_by_column
else:
get_attr = instance_mapper._get_state_attr_by_column
If we are in the middle of a flush, we don't attempt a query but rather
use the committed state. This caused me problems when the committed
state of the relationship was "None" (for example, not loaded yet?)
For my own understanding, what implications does this have? It kind of
freaked me out because I interpreted that as meaning "I'm not sure if I
can rely upon unloaded relationships at all from within these mid-flush
event methods..." because I certainly don't want to be using stale, old
data. Is there a threat of this, or only of it sometimes being "None"?
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