Thanks for your reply,
> OK, i had the impression you were switching the mapper inside of a
> relation() somehow, but it seems all youre doing is sticking a mapper
> on a property (i dont quite understand how youd use it ? )
>
I want to use it like this
fixRace(dbPeople, myrace)
listofgreeks=session.query(dbPeople.inRace).select_by(Nationality="Greece")
listofresident=session.query(dbPeople.inRace).select_by(Country="Germany")
So I need to have the "inRace" mapper an attribute of the class itself.
I'll stick to what I have right now, it seems to work fine.
Cheers,
François
> if i understand properly, id just do it this way:
>
> class dbPeople(object):
> def fixRace(self, race):
> self._race_id = race.id
> def _in_race(self):
> return object_session(self).query(dbRace).select(
> and_(tblRaceParticipant.c.Race_id==self._race_id,tblPeople.c.id==tblRacePar
>ticipant.c.Racer_id)) inRace = property(_in_race)
>
> François Wautier wrote:
> > Hi Michael,
> >
> > Thanks for your reply.
> >
> > First an apology, my program is now working.... It was a silly mistake...
> >
> > Second, I agree that what I am doing is not the most elegant thing I've
> > ever done... .to put it mildly... Yet, in most cases, the "fixRace"
> > function will only be run once at startup ..... In all but one case you
> > only deal with one race. So that's not as bad as it sounds... Still the
> > application that input data into the database does need to deal with
> > multiple races. In that case I only keep one secondary mapper attached to
> > the class and only create a new one when needed (i.e. when the race
> > changes) (I probably need to "delete" the old mapper if present)
> >
> > At the bottom you will see the actual definition/mapping I use.
> >
> > I guess that I may be able to map the various attributes of dbPeople and
> > dbRace to attributes of dbRaceParticipant and deal with that object when
> > needed, but I still see no elegant way of "fixing" the race, either I
> > create a secondary mapper (same as now essentially) or I need to pass the
> > race as an argument to all my queries... which is exactly what I am
> > trying to avoid.
> >
> > Cheers,
> > François
> >
> > Here is an excerpt of my definitions.... draft in progress
> >
> > =========+%<================%<================
> > tblPeople=Table("People",
> > Column("id", Integer, primary_key = True),
> > Column("Nickname",Unicode(32),nullable=False,index=True),
> > Column("Firstname",Unicode(32),nullable=False),
> > Column("Lastname",Unicode(32),nullable=False,index=True),
> > Column("Email",VARCHAR(64),index=True),
> > Column("Birthdate",Date),
> > Column("Gender",Enum(["Male","Female"]),nullable=False),
> > Column("Nationality",Country,nullable=False),
> > Column("Address",Unicode(256)),
> > Column("Zip",Unicode(32)),
> > Column("Country",Country),
> > Column("Tel",String(16)),
> > Column("Tel_Ext",String(4)),
> > Column("Mobile",String(16)),
> > Column("Picture_id",Integer,ForeignKey("ADM_Files.id"),
> > nullable=True), Column("Tag",String(32)),
> > Column("Active",Boolean,default=True))
> >
> > tbbPeopleidx=Index('OnlyOne', tblPeople.c.Nickname,tblPeople.c.Firstname,
> > tblPeople.c.Lastname, unique=True)
> >
> > class dbPeople(object):
> >
> > def __str__(self):
> > return self.Fullname()
> >
> > def Fullname(self):
> > return unicode(self.Firstname)+u" "+unicode(self.Lastname)
> >
> > def age(self,adate=None):
> > """Compute the age of a person. If adate is set the age is
> > computed at the given date"""
> > if adate is None:
> > adate=datetime.date.today()
> > myage=adate.year-self.Birthdate.year
> > if adate.month<self.Birthdate.month:
> > myage -=1
> > elif adate.month==self.Birthdate.month:
> > if adate.day<self.Birthdate.day:
> > myage -=1
> > return myage
> >
> >
> > # Mapping a Racer with a Race
> > tblRaceParticipant=Table("Race_Participant",
> > Column("id", Integer, primary_key = True),
> > Column("Race_id",Integer,ForeignKey("Race.id"), nullable=False),
> > Column("Racer_id",Integer,ForeignKey('People.id'), nullable=False),
> > Column("Team_id",Integer,ForeignKey('Team.id'), nullable=True),
> > Column("Weight",DECIMAL(4,1), nullable=True),
> > Column("Age",Integer, nullable=True),
> > Column("Height",Integer, nullable=True),
> > #Column("Categories",String, nullable=True),
> > Column("isActive",Boolean, nullable=False,default=True),
> > Column("Retired",TIMESTAMP, nullable=True),
> > Column("Comment",Unicode))
> >
> > tbbParticipantidx=Index('OnlyOne',
> > tblRaceParticipant.c.Race_id,tblRaceParticipant.c.Racer_id, unique=True)
> >
> > class dbRaceParticipant(object):
> >
> > def __str__(self):
> > return str(self.Racer)+u" during "+str(self.Race)
> >
> > #Defining races
> > tblRace=Table("Race",
> > Column("id", Integer, primary_key = True),
> > Column("Name",Unicode(64),nullable=False),
> > Column("Type",Enum(["Team","Individual"]),nullable=False),
> > Column("Vehicle",Enum(["None","One","Multiple","Individual"]),nullable=Fa
> >lse,default="One"),
> > Column("Organiser_id",Integer,ForeignKey('People.id'),nullable=True),
> > Column("Description",Unicode),
> > Column("Logo_id",Integer,ForeignKey("ADM_Files.id"), nullable=True),
> > Column("Standing",Unicode(32)))
> >
> >
> > class dbRace(object):
> > def __str__(self):
> > return self.Name
> >
> > def getRegistrationRecord(self,people):
> > """There must be a session here"""
> > for rec in self.Registration:
> > if rec.Racer==people:
> > return rec
> >
> > #
> > dbRaceParticipant.mapper=mapper(dbRaceParticipant, tblRaceParticipant,
> > properties = {
> > 'Races' : relation(dbRace, backref=backref('Registration')),
> > 'Racer' : relation(dbPeople, backref=backref('Registration')),
> > "Team":relation(dbTeam )})
> >
> > # Organiser with back reference
> > dbRace.mapper=mapper(dbRace, tblRace,
> > properties = {
> > 'Organiser' : relation(dbPeople, backref=backref('Organise')),
> > "Racers":relation(dbPeople,secondary=tblRaceParticipant,
> > primaryjoin=tblRace.c.id==tblRaceParticipant.c.Race_id,
> > secondaryjoin=tblPeople.c.id==tblRaceParticipant.c.Racer_id),
> > "Teams":relation(dbTeam,secondary=tblRaceParticipant,
> > primaryjoin=tblRace.c.id==tblRaceParticipant.c.Race_id,
> > secondaryjoin=tblTeam.c.id==tblRaceParticipant.c.Team_id),
> > "Logo":relation(dbFile)})
> >
> >
> > # Picture is mapped to the corresponding file.
> > #We have a list of participation record
> > dbPeople.mapper=mapper(dbPeople, tblPeople, properties = {'Picture' :
> > relation(dbFile, cascade="all")})
> >
> > def fixRace(obj,race):
> > """Create a secondary mapper where the race is fixed
> >
> > This has nothing to do with "fixing races", This limits the
> > dataset to those records directly related to the race at hand
> > """
> > if isinstance(race,int):
> > myraceid=race
> > else:
> > myraceid=race.id
> >
> > try:
> > test=obj.fixedRaceId != myraceid
> > except:
> > test=True
> >
> > if test:
> > if obj==dbPeople:
> >
> > s=tblPeople.select(and_(tblRaceParticipant.c.Race_id==myraceid,tblPeople.
> >c.id==tblRaceParticipant.c.Racer_id)).alias("per_race_select")
> >
> > dbPeople.inRace=mapper(dbPeople,s,non_primary=True)
> >
> >
> > =========+%<================%<================
> >
> > > Michael Bayer wrote:
> > > if you are creating mappers within functions on a per-request basis,
> > > that is a Very Bad Idea. dont create ad-hoc mappers just to create
> > > queries. you should only have one mapper per class, corresponding to
> > > the scope of the class itself. i am beginning to consider if the
> > > "non_primary" keyword argument to mapper can even be deprecated since i
> > > am hypothesizing that it doesn't provide any unique functionality, and
> > > only leads to problems.
> > >
> > > if you want a particualr query to occur, you should create the query
> > > you want yourself. without seeing anything that you are doing, if you
> > > are having issues, things like that would be the biggest reason.
>
>
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