On Fri, Jun 21, 2019, at 2:14 AM, Chris Withers wrote: > On 20/06/2019 16:00, 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]), > >>> > >>> 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. > > Yikes, that escalated quickly. > > It probably makes sense just to lose the polymorphic-ness in this case, > I'm not getting enough from it to make the above sensible...
something that is changing is likely not a good candidate for polymorphic identity. That said, you can still have different classes for your "status' if you map the "status" distinctly into a lookup table, and then have your primary object refer to that "status" with a many-to-one relationship. Or you could use an enumeration class with the Enum datatype. > > 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 > Verifiable Example. See http://stackoverflow.com/help/mcve for a full > description. > --- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+unsubscr...@googlegroups.com. > To post to this group, send email to sqlalchemy@googlegroups.com. > Visit this group at https://groups.google.com/group/sqlalchemy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sqlalchemy/4e56afd0-14ca-e767-7e54-39d0813b8f1a%40withers.org. > For more options, visit https://groups.google.com/d/optout. > -- 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. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at https://groups.google.com/group/sqlalchemy. To view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/d0cb6b5f-d0cb-465d-b3f9-929eca8c303e%40www.fastmail.com. For more options, visit https://groups.google.com/d/optout.
