primary_language = Column(String(50))
__mapper_args__ = {'polymorphic_identity': 'engineer'}
-If you want to use a similar pattern with a mix of single and joined
-table inheritance, you would need a slightly different mixin and use
-it on any joined table child classes in addition to their parent
-classes::
-
- from sqlalchemy.ext.declarative import declared_attr
- from sqlalchemy.ext.declarative import has_inherited_table
-
- class Tablename(object):
- @declared_attr
- def __tablename__(cls):
- if (has_inherited_table(cls) and
- Tablename not in cls.__bases__):
- return None
- return cls.__name__.lower()
-
- class Person(Tablename, Base):
- id = Column(Integer, primary_key=True)
- discriminator = Column('type', String(50))
- __mapper_args__ = {'polymorphic_on': discriminator}
-
- # This is single table inheritance
- class Engineer(Person):
- primary_language = Column(String(50))
- __mapper_args__ = {'polymorphic_identity': 'engineer'}
-
- # This is joined table inheritance
- class Manager(Tablename, Person):
- id = Column(Integer, ForeignKey('person.id'), primary_key=True)
- preferred_recreation = Column(String(50))
- __mapper_args__ = {'polymorphic_identity': 'engineer'}
Combining Table/Mapper Arguments from Multiple Mixins
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~