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Mike Bayer
02c9d3ab43
Reworked the handling of classes which extend from MappedAsDataclass but are not themselves mapped, i.e. the declarative base as well as any mixins or abstract classes. These classes as before are turned into real dataclasses, however a scan now takes place across the mapped elements such as mapped_column(), relationship(), etc. so that we may also take into account dataclasses.field-specific parameters like init=False, repr, etc. The main use case for this is so that mixin dataclasses may make use of "default" in fields while not being rejected by the dataclasses constructor. The generated classes are more functional as dataclasses in a standalone fashion as well, even though this is not their intended use. As a standalone dataclass, the one feature that does not work is a field that has a default with init=False, because we still need to have a mapped_column() or similar present at the class level for the class to work as a superclass. The change also addes the :func:`_orm.unmapped_dataclass` decorator function, which may be used to create unmapped superclasses in a mapped hierarchy that is using the :func:`_orm.mapped_dataclass` decorator to create mapped dataclasses. Previously there was no way to use unmapped dataclass mixins with the decorator approach. Finally, the warning added in 2.0 for 🎫`9350` is turned into an error as mentioned for 2.1, since we're deep into dataclass hierarchy changes here. Fixes: #12854 Change-Id: I11cd8c628d49e9ff1bdbda8a09f4112b40d84be7