Thanks for this very important information! If I do want to utilize the mapper functions at this stage, what can I do? currently I have this error showing up:
AttributeError: 'Mapper' object has no attribute '_columntoproperty' On Friday, October 8, 2021 at 6:58:02 AM UTC-7 Mike Bayer wrote: > > > On Fri, Oct 8, 2021, at 7:09 AM, niuji...@gmail.com wrote: > > In order to make sure that the mapped class is fully ready, I chose the > latest point, namely `class_instrument`. > However, it seems that at that moment the `__mapper__` attribute is not > available. > When I tried > return cls.__mapper__.get_property_by_column(column_obj).key > > I got: > AttributeError: type object 'GeoAreaVariantName' has no attribute > '__mapper__' > > Is this a bug or a feature? > > > it's a normal behavior, that event is called before mapping has been > established. > > but also, the "__mapper__" attribute is a convenience feature that should > not be relied upon at this stage. the correct way to get the mapper for a > class is to use the sqlalchemy.inspect() function, i.e. mapper = > inspect(class). > > > > > On Wednesday, October 6, 2021 at 5:36:22 AM UTC-7 Mike Bayer wrote: > > > events that occur around this time include > > this one claims it's before: > > > https://docs.sqlalchemy.org/en/14/orm/events.html#sqlalchemy.orm.MapperEvents.instrument_class > > this one says after: > > > https://docs.sqlalchemy.org/en/14/orm/events.html#sqlalchemy.orm.InstrumentationEvents.class_instrument > > this one is definitely after and is usually fine for anything that needs > to happen for mapped classes before they are reconciled against other > classes: > > > https://docs.sqlalchemy.org/en/14/orm/events.html#sqlalchemy.orm.MapperEvents.before_mapper_configured > > > On Wed, Oct 6, 2021, at 4:48 AM, niuji...@gmail.com wrote: > > I want to do some after processing on each class that is just put into > the class_registry. Is there a event hook for this? > > > -- > 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+...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sqlalchemy/6ec43831-d59e-4343-99cf-dce3773a1216n%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/6ec43831-d59e-4343-99cf-dce3773a1216n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > > -- > 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+...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/sqlalchemy/066675cb-164a-4f61-9764-15ac402b6a3bn%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/066675cb-164a-4f61-9764-15ac402b6a3bn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sqlalchemy/fb457c38-74a2-4ce6-bb1c-35157347fd9fn%40googlegroups.com.
