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 ? )
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==tblRaceParticipant.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=False,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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