I think it was missing a key in foreign_keys:
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[data.c.id_meas, acquisitions.c.id_cu],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
Now it seems work as expected, thanks.
On Feb 28, 1:03 pm, neurino neur...@gmail.com wrote:
Sorry if I resume this after two months but I think there's a bug in
cascade deletion of the relationship you suggested me:
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[data.c.id_meas],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
since, on a cascade delete of a Sensor sqlalchemy issues this query:
SELECT data.id AS data_id, data.id_acq AS data_id_acq, data.id_meas AS
data_id_meas, data.id_elab AS data_id_elab, data.value AS data_value
FROM data, acquisitions, sensors
WHERE ? = data.id_meas AND data.id_acq = acquisitions.id AND
acquisitions.id_cu = sensors.id_cu
(1,)
DELETE FROM data WHERE data.id = ?
that's going to delete all data with id_meas = 1 while it should be
SELECT data.id AS data_id, data.id_acq AS data_id_acq, data.id_meas AS
data_id_meas, data.id_elab AS data_id_elab, data.value AS data_value
FROM data, acquisitions, sensors
WHERE ? = data.id_meas AND ? = acquisitions.id_cu AND data.id_acq =
acquisitions.id AND acquisitions.id_cu = sensors.id_cu
(1, 3)
DELETE FROM data WHERE data.id = ?
with the `AND ? = acquisitions.id_cu` part added because Sensor has a
composite primary key (id_cu, id_meas).
I know it's a rare situation so I have no problems in removing cascade
and doing deletions on my own but I'd like to be sure it's not a fault
of mine but a bug.
Thanks for your support.
On Dec 30 2010, 5:45 pm, Michael Bayer mike...@zzzcomputing.com
wrote:
this is again my error messages not telling the whole story, ill see if i
can get the term foreign_keys back in there:
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[data.c.id_meas],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
or
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[sensors.id_meas],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
depending on if this is one-to-many or many-to-one. A relationship like
this is really better off as a viewonly=True since populating it is not
going to add rows to the acquisitions table.
On Dec 30, 2010, at 10:15 AM,neurinowrote:
data = Table('data', metadata,
Column('id', Integer, primary_key=True),
Column('id_acq', Integer, ForeignKey('acquisitions.id'),
nullable=False),
Column('id_meas', Integer, nullable=False),
Column('value', Float, nullable=True),
)
acquisitions = Table('acquisitions', metadata,
Column('id', Integer, primary_key=True),
Column('id_cu', Integer, ForeignKey('ctrl_units.id'),
nullable=False),
Column('datetime', DateTime, nullable=False),
)
sensors = Table('sensors', metadata,
Column('id_cu', Integer, ForeignKey('ctrl_units.id'),
primary_key=True,
autoincrement=False),
Column('id_meas', Integer, primary_key=True, autoincrement=False),
Column('name', Unicode(20), nullable=False),
Column('desc', Unicode(40), nullable=False),
)
ctrl_units = Table('ctrl_units', metadata,
Column('id', Integer, primary_key=True, autoincrement=False),
Column('desc', Unicode(40), nullable=False)
)
and this mapping:
...
orm.mapper(Sensor, sensors,
properties={
'data': orm.relationship(Data, backref='sensor',
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
...
--
You received this message because you are subscribed to the Google Groups
sqlalchemy group.
To post to this group,
