Hei Wes and Paul...
On 10/29/07, Wes Duff <[EMAIL PROTECTED]> wrote:
> Hey whats going on.
> I am a new sqlalchemist as well but lets see if this helps any.
>
> This is how I am getting a list of all names that corrispond with my
> document names class.
>
> names = [ c.name for c in model.Document.select_by(param=param) ]
> So I am just collecting all the names from my Document table. I added
> select_by(param=param) if you want to find all the names that have to do
> with a parameter.
> names becomes a list
>
> I hope this helps a little.
I think you misunderstood Paul's question (which I'm also waiting for
response)... :)
What Paul is asking is: given this mapping:
mapper(User, users_table)
mapper(Address, addresses_table, properties={
'user' : relation(User, backref='addresses', lazy=False)
})
We are able to know that Address class has a reference to User class
by introspecting its mapper's properties:
>>> q = session.query(Address)
>>> q.mapper.properties['user']
<sqlalchemy.orm.properties.PropertyLoader object at 0x013094D0>
However, if the relation is declared this way:
mapper(Address, addresses_table)
mapper(User, users_table, properties={
'addresses' : relation(Address, backref='user', lazy=False)
})
... our introspection gives us:
>>> q = session.query(Address)
>>> q.mapper.properties['user']
Traceback (most recent call last):
File "<pyshell#42>", line 1, in -toplevel-
q.mapper.properties['user']
KeyError: 'user'
But Address actually has a user property... :(
If we need to introspect both Address->user and User->addresses, one
solution is to not use the backref ... :
mapper(User, users_table, properties={
'addresses' : relation(Address, lazy=False)})
mapper(Address, addresses_table, properties={
'user' : relation(User, lazy=False)})
>>> q = session.query(User)
>>> q.mapper.properties['addresses']
<sqlalchemy.orm.properties.PropertyLoader object at 0x01313F70>
>>> q = session.query(Address)
>>> q.mapper.properties['user']
<sqlalchemy.orm.properties.PropertyLoader object at 0x013134F0>
BTW, one practical use of this introspection can be found at:
http://trac.turbogears.org/ticket/1582
> On Oct 29, 2007 11:21 AM, Paul Johnston <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > How do I get a list of the relations a mapper has? I've been using
> mapper.properties, but have just realised this doesn't pick up backrefs.
/me too... :)
> > Any ideas? Thanks,
I also want to know that...
Cheers,
Roger
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