[sqlalchemy] Re: Relation w/ declarative
Allen, allen.fowler wrote: ... > > What is that __repr__ function doing exactly? Looks interesting. > It is really useful, and yes Michael comes up with beauties like this. Produces nice print output, i.e.: print 'after flush' print con print add Will give you: after flush Contact(address=[Address(contact=Contact(address=[...], id=7, name='a name'), fk_contact=7, id=8, street='a street')], id=7, name='a name') Address(contact=Contact(address=[Address(contact=Contact(address=[...], id=7, name='a name'), fk_contact=7, id=8, street='a street')], id=7, name='a name'), fk_contact=7, id=8, street='a street') If it were not there you would get: after flush Werner --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Relation w/ declarative
On Aug 6, 4:59 am, Wichert Akkerman wrote:
> On 8/6/09 09:30 , werner wrote:
>
> > 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'
>
> You can also do this with the default declarative base constructor:
>
> add = Address(email_address='j...@example.com')
>
> All columns can be used as named parameters.
>
Brilliant! :)
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[sqlalchemy] Re: Relation w/ declarative
On Aug 6, 3:30 am, werner wrote:
> 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()
>
OK, that explains it. Thank you.
> 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
>
What is that __repr__ function doing exactly? Looks interesting.
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[sqlalchemy] Re: Relation w/ declarative
On 8/6/09 09:30 , werner wrote:
> 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'
You can also do this with the default declarative base constructor:
add = Address(email_address='j...@example.com')
All columns can be used as named parameters.
Wichert.
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[sqlalchemy] Re: Relation w/ declarative
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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