On Fri, Oct 8, 2021, at 4:13 PM, niuji...@gmail.com wrote: > 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'
you would need to show me a stack trace on that. however, depending on which event you are using to get at the mapper, it may not be initialized yet (can confirm that class_instrument() event is too early if access to the internals of the mapper is required). as stated previously, the best event to use when a class is first mapped but before the full span of mappings have been considered is the before_mapper_configured() event (can confirm _columntoproperty is available at that stage). > 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 > > <https://groups.google.com/d/msgid/sqlalchemy/fb457c38-74a2-4ce6-bb1c-35157347fd9fn%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. 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