Examples¶
Single table inheritance¶
from sqlalchemy_things.declarative import (
IntegerPrimaryKeyMixin,
PolymorphicMixin,
)
metadata = sa.MetaData()
Base = orm.declarative_base(metadata=metadata)
class Parent(Base, IntegerPrimaryKeyMixin, PolymorphicMixin):
__tablename__ = 'single_table'
class ChildA(Parent):
__mapper_args__ = {'polymorphic_identity': 'child_a'}
some_field = sa.Column(sa.String(255))
class ChildB(Parent):
__mapper_args__ = {'polymorphic_identity': 'child_b'}
other_filed = sa.Column(sa.String(127))
Joined table inheritance with cascade primary key mixins¶
from sqlalchemy_things.declarative import (
CascadeIntegerPrimaryKeyMixin,
PolymorphicMixin,
)
metadata = sa.MetaData()
Base = orm.declarative_base(metadata=metadata)
class Parent(Base, CascadeIntegerPrimaryKeyMixin, PolymorphicMixin):
__tablename__ = 'cascade_pk_parent_table'
class ChildA(Parent):
__tablename__ = 'cascade_pk_child_table_a'
__mapper_args__ = {'polymorphic_identity': 'child_a'}
field = sa.Column(sa.String(255))
class ChildB(Parent):
__tablename__ = 'cascade_pk_child_table_b'
__mapper_args__ = {'polymorphic_identity': 'child_b'}
field = sa.Column(sa.String(127))
Joined table inheritance with simple primary key mixins¶
from sqlalchemy_things.declarative import (
IntegerPrimaryKeyMixin,
ParentPrimaryKeyMixin,
PolymorphicMixin,
)
metadata = sa.MetaData()
Base = orm.declarative_base(metadata=metadata)
class Parent(Base, IntegerPrimaryKeyMixin, PolymorphicMixin):
__tablename__ = 'inherited_pk_parent_table'
class ChildA(ParentPrimaryKeyMixin, Parent):
__tablename__ = 'inherited_pk_child_table_a'
__mapper_args__ = {'polymorphic_identity': 'child_a'}
field = sa.Column(sa.String(255))
class ChildB(ParentPrimaryKeyMixin, Parent):
__tablename__ = 'inherited_pk_child_table_b'
__mapper_args__ = {'polymorphic_identity': 'child_b'}
field = sa.Column(sa.String(127))