Dnia 2009-09-25, Pt o godzinie 21:24 -0400, thatsanicehatyouh...@mac.com
pisze:
> Hello,
>
> I am wondering if it's possible to simplify a method I have defined. I
> have a few classes that are autoloaded:
>
> PlatePointing, Plate, Plugging, PlPlugMapM
>
> All are related, and all defined in this manner:
>
> class Plate(Base):
> __tablename__ = 'plate'
> __table_args__ = {'autoload' : True}
>
> Later, I define my relationships. I want to define an attribute that
> performs a more complicated query, and this works:
>
> def platePointing(self,session):
> try:
> pp = session.query(PlatePointing)\
> .join(Plate, Plugging)\
> .filter(Plate.pk==self.plugging.plate.pk)\
>
> .filter(PlatePointing.pointing_name==self.pointing_name).one()
> except sqlalchemy.orm.exc.NoResultFound:
> pp = None
> return pp
>
> PlPlugMapM.platePointing = platePointing
>
>
> My question is, can this be written so that I don't need to pass in
> the session? I don't know how else to perform the query (or return the
> object) without that.
>
First... why don't you define this method with class definition? I don't
use "reflection" but I think that it is possible...
Second... you could probably convert it to column_property
And back to your question..
1. you can have globally accessed session (like it is done in Pylons via
meta.Session)
http://wiki.pylonshq.com/display/pylonsdocs/Using+SQLAlchemy+with+Pylons
2. you can get session for instance using
sqlalchemy.orm.session.Session.object_session
http://www.sqlalchemy.org/docs/05/reference/orm/sessions.html?highlight=session#sqlalchemy.orm.session.Session.object_session
3. You can have "session-aware class"
http://www.sqlalchemy.org/trac/wiki/UsageRecipes/SessionAwareMapper
---
Tomasz Jezierski
Tefnet
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