hey Phil -
reflection bug. Heres a workaround for now:
orders_table = Table('orders', metadata,
Column('order_id', Integer, Sequence('orders_order_id_seq'),
primary_key=True),
autoload=True)
On Jan 28, 2008, at 4:03 PM, Phil Coombs wrote:
>
> Hi
>
> I'm a Python and SA newbie investigating SA for a project using
> Postgres. I have a database schema that I want to point SA at then be
> able to write my Python code.
>
> I'm working with a version of the basic_association example to keep
> things simple. I want to have unique auto generated ids on my tables
> (surrogate primary keys) but also want to have primary keys defined
> over the entities' actual attributes. I want to have surrogate keys on
> my tables so that I can use them instead of the full priamary keys
> when writing joins to keep the SQL brief. In some cases (e.g. the
> association table) I'm defining the primary key in terms of surrogate
> primary keys rather than copy over the full primary key from the
> associated tables.
>
> When I run the code (below) I get AttributeError: 'Order' object has
> no attribute '_instance_key'.
>
> Please can someone help me setup SA to work in this example?
>
> Thanks in advance
>
> Phil
>
> Postgress DDL
> ----------------------
> create table orders (
> order_id Serial ,
> o_customer_name text not null,
> o_order_date timestamp not null,
> primary key (o_customer_name, o_order_date) using index ,unique
> (order_id);
>
> create table items (
> item_id Serial ,
> it_description text not null,
> it_price Numeric(8,2) not null,
> primary key (it_description) using index, unique (item_id) using
> index);
>
> create table order_items (
> oi_order_id Integer not null,
> oi_item_id Integer not null,
> oi_price Numeric(8,2) not null,
> primary key (oi_order_id, oi_item_id) using index);
>
> Python
> ----------
> [SNIP] setup and connect string
>
> engine = create_engine(connectString, echo=False)
> metadata = MetaData(engine)
>
> orders_table = Table('orders', metadata, autoload=True)
> items_table = Table('items', metadata, autoload=True)
> orderitems_table = Table('order_items', metadata,
> Column('oi_order_id', Integer,
> ForeignKey('orders.order_id'),
> primary_key=True),
> Column('oi_item_id', Integer,
> ForeignKey('items.item_id'),
> primary_key=True),
> autoload=True
> )
>
> class Order(object):
> def __init__(self, customer_name, order_date):
> self.customer_name = customer_name
> self.order_date = order_date
>
> class Item(object):
> def __init__(self, description, price):
> self.description = description
> self.price = price
>
> class OrderItem(object):
> def __init__(self, item, price=None):
> self.item = item
> self.price = price or item.price
>
> mapper(Order, orders_table, properties = {
> 'id' : orders_table.c.order_id,
> 'customer_name' : orders_table.c.o_customer_name,
> 'order_date' : orders_table.c.o_order_date,
> 'order_items' : relation(OrderItem)
> })
>
> mapper(Item, items_table, properties = {
> 'id' : items_table.c.item_id,
> 'description' : items_table.c.it_description,
> 'price' : items_table.c.it_price
> })
>
> mapper(OrderItem, orderitems_table, properties = {
> 'order_id' : orderitems_table.c.oi_order_id,
> 'item_id' : orderitems_table.c.oi_item_id,
> 'price' : orderitems_table.c.oi_price,
> 'item' : relation(Item)
> })
>
> Session = sessionmaker(bind=engine, autoflush=True,
> transactional=True)
> session = Session()
>
> session.save(Item('Item A', 10.99))
> session.save(Item('Item B', 8))
> session.save(Item('Item C', 4))
> session.save(Item('Item D', 1))
> session.flush()
>
> def item(name):
> return session.query(Item).filter_by(description=name).one()
>
> order = Order("cust1", datetime.now())
> order.order_items.append(OrderItem(item('Item A')))
> order.order_items.append(OrderItem(item('Item B'),10))
> order.order_items.append(OrderItem(item('Item C')))
>
> session.save(order)
> session.commit()
>
> >
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