Hi,
AF wrote:
> Am starting to experiment with declarative base.
>
> In the code block at:
>
> http://www.sqlalchemy.org/docs/05/ormtutorial.html#building-a-relation
>
> Why does __init__() not contain any mention of the foreign key
> "user_id"?
>
>
As one normally does not manually set an id - it is done with a sequence
in most cases.
IIRC correctly the __init__ section is only needed if you want to do:
add = Address('an email address')
I never do this, i.e. I assign like this
add = Address()
add.email_address = 'an email address'
> In what way is the Address object expected to be instantiated such
> that it receives the correct user id?
>
You just do this and SA will take care of the id's:
con = db.Contact()
con.name = 'a name'
add = db.Address()
add.street = 'a street'
con.address.append(add)
session.add(con)
session.add(add)
session.commit()
Above is based on this model (db) and the BaseExt was a tip I had from
Michael.
class BaseExt(object):
def __repr__(self):
return "%s(%s)" % (
(self.__class__.__name__),
', '.join(["%s=%r" % (key, getattr(self, key))
for key in sorted(self.__dict__.keys())
if not key.startswith('_')]))
Base = sad.declarative_base(cls=BaseExt)
metadata = Base.metadata
class Contact(Base):
__table__ = sa.Table(u'contact', metadata,
sa.Column(u'id', sa.Integer(), sa.Sequence('gen_contact_id'),
primary_key=True, nullable=False),
sa.Column(u'name', sa.String(length=70, convert_unicode=False),
nullable=False),
)
class Address(Base):
__table__ = sa.Table(u'address', metadata,
sa.Column(u'id', sa.Integer(), sa.Sequence('gen_contact_id'),
primary_key=True, nullable=False),
sa.Column(u'street', sa.String(length=70, convert_unicode=False),
nullable=False),
sa.Column(u'fk_contact', sa.Integer(), sa.ForeignKey(u'contact.id'),
nullable=False),
)
contact = sao.relation('Contact', backref='address')
Werner
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