On Thu, Jun 20, 2019, at 10:41 AM, Mike Bayer wrote:
>
>
> On Thu, Jun 20, 2019, at 3:14 AM, Chris Withers wrote:
>> Hi All,
>>
>> I'm getting this warning:
>>
>> SAWarning: Flushing object <Cancelled at 0x10b1b9d30> with incompatible
>> polymorphic identity <Types.done: 'DONE'>; the object may not refresh
>> and/or load correctly (this warning may be suppressed after 10 occurrences)
>> (state_str(state), dict_[polymorphic_key]),
>>
>> I know why: I'm changing the polymorphic type of a row, but this is
>> intentional (it's handling a PUT to the entity the row represents) and I
>> don't believe I'll hit refresh or load problems since once the
>> transaction is committed, I'm done with the session.
>>
>> So, two questions:
>>
>> How can I indicate in my code that this is intentional and no warning
>> should be omitted?
>
> you would need to change its class, or replace it with a new object of the
> correct class. in both cases you probably need to pull the object out of the
> Session and put it in again. if you are making a new object, you would use
> make_transient_to_detached() to give the object a persistent primary key
> identity then use session.add() to put it back in again:
>
> https://docs.sqlalchemy.org/en/13/orm/session_api.html?highlight=make_transient#sqlalchemy.orm.session.make_transient_to_detached
>
> if you are doing "obj.__class__ = newclass", you probably need to do the same
> thing plus more because the identity key needs to have the new class in it,
> so you could make_transient() to erase the old identity key and then
> make_transient_to_detached() to give it back a new identity key, then
> session.add() it.
>
> in both of *those* cases, the history of the object is reset to "clean", so
> anything you actually want to persist on the object needs to be applied after
> you've recreated it as a new class with a new identity key.
>
> still another way, that would not reset the history, you can also manipulate
> state.key directly to have the correct identity key and then replace the
> object, e.g.
>
> session.expunge(obj)
> obj.__class__ = newclass
> obj.polymorphic_identity = 'new_identity'
> inspect(obj).key = sqlalchemy.orm.identity_key(instance=obj)
> session.add(obj)
>
> I'd probably want to make a new object and not change __class__, because
> changing __class__ in the general case indicates you're going to have an
> object where its __dict__ can be in an invalid state vs. what the class
> expects.
>
>
>
>>
>> Why does the following warning filter not work?
>>
>> warnings.filterwarnings("ignore", category=SADeprecationWarning)
>> warnings.filterwarnings("ignore", category=SAWarning)
>>
>> The SADeprecationWarning filter *does* work (and is somewhat legit as
>> they're coming from a third party library that's awaiting a fix), but
>> the SAWarning doesn't catch the above.
>
> that is news to me, if that can be demonstrated that should be posted as a
> new bug. suspect the _hash_limit_string() aspect that is doing the
> "suppressed after 10 occurrences" part.
this is not reproducing for me:
from sqlalchemy import util
import warnings
from sqlalchemy import exc
warnings.filterwarnings("ignore", category=exc.SAWarning)
util.warn_limited(
"Flushing object %s with "
"incompatible polymorphic identity %r; the "
"object may not refresh and/or load correctly",
(object(), 'foo'),
)
with the filter I get no output
>
>
>>
>> cheers,
>>
>> Chris
>>
>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
>> To post example code, please provide an MCVE: Minimal, Complete, and
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>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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