Going back to the subject ))
I get error (and no data updated) while using no_autoflush
/Users/sector119/PythonVirtualEnv/supplements/lib/python2.7/site-packages/sqlalchemy/orm/session.py:2122:
SAWarning: Attribute history events accumulated on 1 previously clean
instances within inner-flush event handlers have been reset, and will not
result in database updates. Consider using set_committed_value() within
inner-flush event handlers to avoid this warning.
def reviews_after_insert_listener(mapper, connection, target):
session = object_session(target)
with session.no_autoflush:
print repr(target.overview)
target.overview.reviews_count += 1
target.overview.rating_sum += target.overview_rating
target.overview.rating_count += 1
if target.overview_flavor_rating is not None:
target.overview_flavor.rating_sum +=
target.overview_flavor_rating
target.overview_flavor.rating_count += 1
event.listen(ProductOverviewReview, 'after_insert',
reviews_after_insert_listener)
четверг, 25 февраля 2016 г., 15:41:03 UTC+2 пользователь Simon King написал:
>
> Er, ok. There are simpler ways to avoid autoflush
>
> https://bitbucket.org/zzzeek/sqlalchemy/wiki/UsageRecipes/DisableAutoflush
>
> for example:
>
> session = sqlalchemy.orm.object_session(mapper)
> with session.no_autoflush:
> target.product.quantity += (value - oldvalue)
>
> ...but that still doesn't fix your underlying problem, which is that you
> are assigning an unexpected object to your "label" property. I guess
> FieldStorage comes from your web framework, and you need to extract the
> actual value from that before assigning it to your mapped object.
>
> Simon
>
> On Thu, Feb 25, 2016 at 1:24 PM, sector119 <sect...@gmail.com
> <javascript:>> wrote:
>
>> Thanks a lot, I add
>>
>> @event.listens_for(ProductFlavor, 'after_update')
>> def quantity_before_update_listener(mapper, connection, target):
>> quantity =
>> select([func.coalesce(func.sum(ProductFlavor.__table__.c.quantity),
>> 0)]).where(
>> ProductFlavor.__table__.c.product_id == Product.__table__.c.id)
>> connection.execute(
>> Product.__table__.update().where(Product.__table__.c.id ==
>> target.product_id).values(quantity=quantity))
>>
>>
>> четверг, 25 февраля 2016 г., 11:52:50 UTC+2 пользователь Simon King
>> написал:
>>>
>>> On Wed, Feb 24, 2016 at 9:51 PM, sector119 <sect...@gmail.com> wrote:
>>>
>>>> Hello!
>>>>
>>>> I have two models, Product and ProductFlavor with one-to-many
>>>> relationship
>>>> And I have a listener, which I want to update Product.quantity on
>>>> ProductFlavor.quantity change:
>>>>
>>>> @event.listens_for(ProductFlavor.quantity, 'set')
>>>> def quantity_set(target, value, oldvalue, initiator):
>>>> if value != oldvalue:
>>>> target.product.quantity += (value - oldvalue)
>>>>
>>>>
>>>> But I get the following error:
>>>>
>>>>
>>>> ProgrammingError: (raised as a result of Query-invoked autoflush;
>>>> consider using a session.no_autoflush block if this flush is occurring
>>>> prematurely)
>>>>
>>>> (psycopg2.ProgrammingError) can't adapt type 'instance' [SQL: 'UPDATE
>>>> product_flavor SET label=%(label)s WHERE product_flavor.id =
>>>> %(product_flavor_id)s'] [parameters: {'product_flavor_id': 4, 'label':
>>>> FieldStorage('label', u'42bbebd1f7ba46b58d3d4b794b4b890e.png')}]
>>>>
>>>> What I'm doing wrong?
>>>>
>>>
>>> It looks like you're assigning a non-string to your "label" column. This
>>> isn't directly related to your attribute listener - the error would happen
>>> even without the attribute listener when you called session.flush() or
>>> session.commit(). The attribute listener is just causing the flush to
>>> happen earlier presumably because "target.product" has not yet been loaded
>>> from the database.
>>>
>>> Simon
>>>
>>>
>>> --
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