I've got the following models and I'd like to automatically filter out
ReservationPackages that contain a "soft deleted" package. A package is
"soft deleted" if deleted != null. I've been struggling with this for a few
days now. The problem goes away if I don't use the proxy but then I cannot
model duplicate packages on my reservation.
class ReservationPackage(db.Model):
""" We must use the association pattern to support duplicate packages on
a reservation """
__tablename__ = "reservation_packages"
id = db.Column(db.Integer, primary_key=True)
reservation_id = db.Column(db.Integer, db.ForeignKey('reservations.id'))
package_id = db.Column(db.Integer, db.ForeignKey('packages.id'))
package = db.relationship("Package")
def __init__(self, package):
self.package = package
class Reservation(db.Model):
""" Reservation represents a contract to rent something to a User """
__tablename__ = "reservations"
id = db.Column(db.Integer, primary_key=True)
# We unfortunately need to use an association like this to
# support the ability to have duplicate packages.
_package_rel = db.relationship(ReservationPackage, lazy="joined")
packages = association_proxy('_package_rel', 'package')
class Package(db.Model):
__tablename__ = "packages"
id = db.Column(db.Integer, primary_key=True)
deleted = db.Column(db.DateTime)
I could create a read only property that contains something like
return object_session(self).query(ReservationPackage) \
.filter_by(reservation_id=self.id) \
.join("package"). \
filter(text("packages.deleted != null")).all()
but I'd really like to be able to manipulate the packages list through the
packages property.
thanks,
-shawn
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