hi, i want to assign details or assemblies to the 'slave' property of the spec lines but i can't. what's wrong with my mapping ?
from sqlalchemy import * from datetime import datetime metadata = BoundMetaData('sqlite://', echo=False) products_table = Table('products', metadata, Column('product_id', Integer, primary_key=True), Column('product_type', String(128)), Column('name', String(128)), Column('mark', String(128)), Column('material', String(128), default=''), Column('sortament', String(128), default=''), Column('weight', String(128), default=''), ) specification_table = Table('specification', metadata, Column('spec_line_id', Integer, primary_key=True), Column('master_id', Integer, ForeignKey("products.product_id"), nullable=True), Column('slave_id', Integer, ForeignKey("products.product_id"), nullable=True), Column('quantity', Float, default=1.), ) class Product(object): def __init__(self, name, mark=''): self.name = name self.mark = mark def __repr__(self): return '<%s %s>' % (self.__class__.__name__, self.name) class Detail(Product): def __init__(self, name, mark='', material='', sortament='', weight=''): self.name = name self.mark = mark self.material = material self.sortament = sortament self.weight = weight class Assembly(Product): pass class SpecLine(object): def __init__(self, master=None, slave=None, quantity=1): self.master = master self.slave = slave self.quantity = quantity def __repr__(self): return '<%s %.01f %s>' % ( self.__class__.__name__, self.quantity or 0., getattr(self.slave, 'name', None) ) product_mapper = mapper(Product, products_table, polymorphic_on=products_table.c.product_type, polymorphic_identity='product') detail_mapper = mapper(Detail, inherits=product_mapper, polymorphic_identity='detail') assembly_mapper = mapper(Assembly, inherits=product_mapper, polymorphic_identity='assembly') specification_mapper = mapper(SpecLine, specification_table, properties=dict( master=relation(Assembly, foreignkey=specification_table.c.master_id, primaryjoin=specification_table.c.master_id==products_table.c.product_id, lazy=True, backref='specification', uselist=False), slave=relation(Product, foreignkey=specification_table.c.slave_id, primaryjoin=specification_table.c.slave_id==products_table.c.product_id, lazy=True, uselist=False), quantity=specification_table.c.quantity, ) ) assembly_mapper.add_property('specification', relation(SpecLine, primaryjoin=specification_table.c.master_id==products_table.c.product_id, lazy=True, private=True, backref='master') ) metadata.create_all() session = create_session() a1 = Assembly(name='a1') p1 = Product(name='p1') a1.specification.append(SpecLine(slave=p1)) d1 = Detail(name='d1') a1.specification.append(SpecLine(slave=d1)) session.save(a1) session.flush() session.clear() a1 = session.query(Product).get_by(name='a1') print a1 print a1.specification