Hi there,
We are migrating our code from SqlAlchemy 1.4 to 2.0 (2.0.23 to be
specific).
We have had the following, which allowed some classes inheriting from
our Base to use an ABCMeta metaclass:
-----------------------------------------------
class DeclarativeABCMeta(DeclarativeMeta, ABCMeta):
pass
metadata = MetaData(naming_convention=naming_convention)
Base = declarative_base(metadata=metadata, metaclass=DeclarativeABCMeta)
-----------------------------------------------
The code above works fine on 2.0, but if we want heed the 2.0 docs that
comment that declarative_base is superceded by using a class inheriting
from DeclarativeBase, we ought to have something like:
-----------------------------------------------
class DeclarativeABCMeta(DeclarativeMeta, ABCMeta):
pass
metadata = MetaData(naming_convention=naming_convention)
class Base(DeclarativeBase, metaclass=DeclarativeABCMeta):
"""A Base for using with declarative."""
__abstract__ = True
metadata = metadata
-----------------------------------------------
This, however breaks when it hits the first class inheriting from Base:
-----------------------------------------------
class SchemaVersion(Base):
__tablename__ = 'reahl_schema_version'
id = Column(Integer, primary_key=True)
version = Column(String(50))
egg_name = Column(String(80))
-----------------------------------------------
With:
[site-packages]/sqlalchemy/orm/decl_api.py:195: in __init__
_as_declarative(reg, cls, dict_)
[site-packages]/sqlalchemy/orm/decl_base.py:247: in _as_declarative
return _MapperConfig.setup_mapping(registry, cls, dict_, None, {})
[site-packages]/sqlalchemy/orm/decl_base.py:328: in setup_mapping
return _ClassScanMapperConfig(
[site-packages]/sqlalchemy/orm/decl_base.py:520: in __init__
super().__init__(registry, cls_, mapper_kw)
[site-packages]/sqlalchemy/orm/decl_base.py:344: in __init__
instrumentation.register_class(
[site-packages]/sqlalchemy/orm/instrumentation.py:684: in register_class
manager._update_state(
[site-packages]/sqlalchemy/orm/instrumentation.py:209: in _update_state
registry._add_manager(self)
[site-packages]/sqlalchemy/orm/decl_api.py:1380: in _add_manager
raise exc.ArgumentError(
E sqlalchemy.exc.ArgumentError: Class '<class
'reahl.sqlalchemysupport.sqlalchemysupport.SchemaVersion'>' already has
a primary mapper defined.
Any ideas on what we are doing wrong here?
Thanks
Iwan
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