hi, i hit another dynamic relations related bug. if you remove
lazy='dynamic' from items mapping there's no problem.
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from sqlalchemy import *
from sqlalchemy.orm import *
metadata = MetaData()
elements = Table('elements', metadata,
Column('id', Integer, primary_key=True),
Column('type', String(128)),
Column('name', String(256)),
)
items = Table('items', metadata,
Column('assembly_id', Integer, ForeignKey('elements.id'), primary_key=True),
Column('element_id', Integer, ForeignKey('elements.id'), primary_key=True),
Column('quantity', Integer, default=1, nullable=False),
)
engine = create_engine('sqlite:///')
metadata.bind = engine
metadata.create_all()
class Element(object):
def __init__(self, name):
self.name = name
def __repr__(self):
return '<%s %s>' % (self.__class__.__name__, self.name)
class Part(Element): pass
class Assembly(Element): pass
class Product(Assembly): pass
class Item(object):
def __init__(self, assembly, element, quantity=1):
self.assembly = assembly
self.element = element
self.quantity = quantity
def __repr__(self):
return '<%s %d %s %s>' % (self.__class__.__name__, self.quantity,
self.assembly.name, self.element.name)
element_mapper = mapper(Element, elements,
polymorphic_on=elements.c.type,
polymorphic_identity='element'
)
part_mapper = mapper(Part, inherits=element_mapper, polymorphic_identity='part')
assembly_mapper = mapper(Assembly, inherits=element_mapper,
polymorphic_identity='assembly')
product_mapper = mapper(Product, inherits=assembly_mapper,
polymorphic_identity='product')
items_select = select(
[items, elements.c.name],
items.c.element_id==elements.c.id
).alias('element_items')
items_mapper = mapper(Item, items_select,
primary_key=[items_select.c.assembly_id, items_select.c.element_id],
order_by=items_select.c.name,
properties=dict(
assembly=relation(
Assembly, lazy=False, uselist=False,
foreign_keys=[items_select.c.assembly_id],
primaryjoin=items_select.c.assembly_id==elements.c.id,
backref=backref('element_items', lazy='dynamic',
primaryjoin=items_select.c.assembly_id==elements.c.id),
),
element=relation(
Element, lazy=False, uselist=False,
foreign_keys=[items_select.c.element_id],
primaryjoin=items_select.c.element_id==elements.c.id,
backref=backref('assembly_items', lazy='dynamic',
primaryjoin=items_select.c.element_id==elements.c.id),
),
quantity=items_select.c.quantity,
)
)
session = create_session(bind=engine)
prod1 = Product('prod1')
session.save(prod1)
part1 = Part('part1')
session.save(part1)
for i in range(2):
assem = Assembly('assem%d' % i)
i1 = Item(prod1, assem)
i2 = Item(assem, part1)
[session.save(o) for o in (assem, i1, i2)]
session.flush()
session.clear()
prod1 = session.query(Product).filter_by(name='prod1').one()
print list(prod1.element_items)
print prod1.element_items[0]
metadata.drop_all()
