Well as I wrote ordering involves everything, also forms creation with formalchemy (make a select where all sensors are ordered that way etc) anyway I understand your point of view.
> quickest is a "where sensor id not in (query)", as a simple WHERE clause Problem comes when Sensor primary key is composite (id_cu + id_meas)... The good 'ol python comes in handy anyway: >>> all = Session.query(model.Sensor).all() >>> selected = Session.query(model.Sensor).filter( ... model.Sensor.id_cu==model.ViewOpt.id_cu).filter( ... model.Sensor.id_meas==model.ViewOpt.id_meas).filter( ... model.ViewOpt.id_view==1).all() >>> diff = [sens for sens in all if sens not in selected] >>> len(all), len(selected), len(diff) (154, 6, 148) We're talking of working on max total 200/300 sensors. The OR way did not filter anything (maybe I made somwthing wrong). Greetings On Jan 12, 4:04 pm, Michael Bayer <[email protected]> wrote: > On Jan 12, 2011, at 8:46 AM, neurino wrote: > > > I need always the same order_by in all app and it could be subject of > > modification and / or integration in the near future so which better > > place than mapper to define it once instead of any time I do a query? > > It sounds like the ordering here is for the purposes of view logic so I'd > have view logic that is factored down to receive Query objects that return > Sensor rows, the view logic then applies the .order_by() to the Query. I.e. > in a web app I use a Paginator object of some kind that does this, given a > Query. This is probably a reason I don't like "order_by" to be within > mapper(), it doesn't define persistence, rather a view. > > > > > Anyway do you think there are alternate paths to get `all sensors but > > already choosen` which are "order_by" compatible? > > quickest is a "where sensor id not in (query)", as a simple WHERE clause, or > use OR, "query sensor where sensor.cu != cu OR sensor.meas != meas OR > sensor.view != view". "Except" is not as widely used and I think its not > even supported by all backends, even though it is a nice logical set > operator, its got annoying quirks like this one. > > > > > > > > > > > Thanks for your support > > > On Jan 12, 2:38 pm, Michael Bayer <[email protected]> wrote: > >> On Jan 12, 2011, at 7:28 AM, neurino wrote: > > >>> I have this model: > > >>> ``I organize views with many view_options each one showing a sensor. > >>> A sensor can appear just once per view.`` > > >>> 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('id_elab', Integer, nullable=False), > >>> Column('name', Unicode(40), nullable=False), > >>> Column('desc', Unicode(80), nullable=True), > >>> ) > > >>> ctrl_units = Table('ctrl_units', metadata, > >>> Column('id', Integer, primary_key=True, autoincrement=False), > >>> Column('name', Unicode(40), nullable=False) > >>> ) > > >>> views = Table('views', metadata, > >>> Column('id', Integer, primary_key=True), > >>> Column('name', Unicode(40), nullable=False), > >>> Column('desc', Unicode(80), nullable=True), > >>> ) > > >>> view_opts = Table('view_opts', metadata, > >>> Column('id', Integer, primary_key=True), > >>> Column('id_view', Integer, ForeignKey('views.id'), > >>> nullable=False), > >>> Column('id_cu', Integer, ForeignKey('ctrl_units.id'), > >>> nullable=False), > >>> Column('id_meas', Integer, nullable=False), > >>> Column('ord', Integer, nullable=False), > >>> ForeignKeyConstraint(('id_cu', 'id_meas'), > >>> ('sensors.id_cu', 'sensors.id_meas')), > >>> #sensor can appear just once per view > >>> UniqueConstraint('id_view', 'id_cu', 'id_meas'), > >>> ) > > >>> Now I let the user add view_options letting him select the sensor. > >>> I'd like to show him only the sensors not already selected in other > >>> options of the same parent view so I tried to use except_ this way: > > >>> q = Session.query(model.Sensor) \ > >>> .except_( > >>> Session.query(model.Sensor) \ > >>> .filter(model.Sensor.id_cu==model.ViewOpt.id_cu) \ > >>> .filter(model.Sensor.id_meas==model.ViewOpt.id_meas) \ > >>> .filter(model.ViewOpt.id_view==1) > >>> ) > > >>> Sensor mapping has a order_by: > > >>> orm.mapper(Sensor, sensors, > >>> order_by=[sensors.c.id_cu, > >>> sensors.c.id_meas > >>> ]) > > >>> I get this SQL and this error, probably due to mapping order_by in > >>> Sensor: > > >>> (OperationalError) ORDER BY clause should come after EXCEPT not > >>> before > >>> u'SELECT anon_1.sensors_id_cu AS anon_1_sensors_id_cu, > >>> anon_1.sensors_id_meas AS anon_1_sensors_id_meas, > >>> anon_1.sensors_id_elab AS anon_1_sensors_id_elab, anon_1.sensors_name > >>> AS anon_1_sensors_name, anon_1.sensors_desc AS anon_1_sensors_desc > >>> FROM (SELECT sensors.id_cu AS sensors_id_cu, sensors.id_meas AS > >>> sensors_id_meas, sensors.id_elab AS sensors_id_elab, sensors.name AS > >>> sensors_name, sensors."desc" AS sensors_desc > >>> FROM sensors ORDER BY sensors.id_cu, sensors.id_meas EXCEPT SELECT > >>> sensors.id_cu AS sensors_id_cu, sensors.id_meas AS sensors_id_meas, > >>> sensors.id_elab AS sensors_id_elab, sensors.name AS sensors_name, > >>> sensors."desc" AS sensors_desc > >>> FROM sensors, view_opts > >>> WHERE sensors.id_cu = view_opts.id_cu AND sensors.id_meas = > >>> view_opts.id_meas AND view_opts.id_view = ? ORDER BY sensors.id_cu, > >>> sensors.id_meas) AS anon_1 ORDER BY anon_1.sensors_id_cu, > >>> anon_1.sensors_id_meas' > > >>> is this supposed to be a bug? > > >>> Any alternative solution (and maybe simpler :) ) to get what I need? > > >> I suppose its a bug, though I'm not a huge fan of "order_by" on mapper > >> though, so my recommendation would be to not rely upon that. A solution > >> in SQLA would be if some flag were passed through to not render built-in > >> order bys. I've added 2022 targeted for 0.7.xx for that. > > > -- > > You received this message because you are subscribed to the Google Groups > > "sqlalchemy" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > For more options, visit this group > > athttp://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. 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