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.),
)
documents_table = Table('documents', metadata,
Column('document_id', Integer, primary_key=True),
Column('document_type', String(128)),
Column('product_id', Integer, ForeignKey('products.product_id')),
Column('create_date', DateTime, default=lambda:datetime.now()),
Column('last_updated', DateTime, default=lambda:datetime.now(),
>
Column('name', String(128)),
Column('data', Binary),
Column('size', Integer, default=0),
)
metadata.create_all()
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)
)
class Document(object):
def __init__(self, name, data="">
self.name = name
self.data = "">
def __repr__(self):
return '<%s %s>' % (self.__class__.__name__, self.name)
class RasterDocument(Document): pass
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, lazy=False, uselist=False,
foreignkey=specification_table.c.master_id,
primaryjoin=specification_table.c.master_id==products_table.c.product_id,
backref=backref('specification', primaryjoin=specification_table.c.master_id==products_table.c.product_id),
),
slave=relation(Product, lazy=False, uselist=False,
foreignkey=specification_table.c.slave_id,
primaryjoin=specification_table.c.slave_id==products_table.c.product_id,
),
quantity=specification_table.c.quantity,
)
)
document_mapper = mapper(Document, documents_table,
polymorphic_on=documents_table.c.document_type,
polymorphic_identity='document',
properties=dict(
name=documents_table.c.name,
data="">
product=relation(Product, lazy=True, backref='documents'),
),
)
raster_document_mapper = mapper(RasterDocument, inherits=document_mapper,
polymorphic_identity='raster_document')
assembly_mapper.add_property('specification',
relation(SpecLine, lazy=True,
primaryjoin=specification_table.c.master_id==products_table.c.product_id,
backref='master', cascade='all, delete-orphan',
)
)
# bug #1
# the property must be added to all the mapers individually, else delete-orphan doesnt work
for m in (product_mapper, assembly_mapper, detail_mapper):
m.add_property('documents',
relation(Document, lazy=True,
backref='product', cascade='all, delete-orphan'),
)
session = create_session()
a1 = Assembly(name='a1')
a1.specification.append(SpecLine(slave=Detail(name='d1')))
a1.documents.append(Document('doc1'))
a1.documents.append(RasterDocument('doc2')) # bug #2
session.save(a1)
session.flush()
session.clear()
del a1
a1 = session.query(Product).get_by(name='a1')
print a1.documents
