OK, thank you,
I went back to SQLA and came up with this for now (simplified):
--------------------------------------------------------
class Pairs(Base):
__tablename__ = 'Pairs'
name = Column(String(20), primary_key=True)
other_name = Column(String(20), ForeignKey('Pairs.name'), nullable
= False)
other = relationship('Pairs',
primaryjoin = 'Pairs.name ==
Pairs.other_name',
remote_side=[name])
def __init__(self, name):
self.name = name
def __repr__(self):
return "(%s, %s)" % (self.name, self.other.name)
def pair(name1, name2):
p1, p2 = Pairs(name1), Pairs(name2)
p1.other_name = name2
p2.other_name = name1
return p1, p2
if __name__ == '__main__':
p1, p2 = pair('apple', 'pear')
session.add_all([p1, p2])
session.commit()
for p in session.query(Pairs).all():
print p
assert p1.other.other is p1
------------------------------------------
Note that there is no backref on "other" and that the primaryjoin is
completely written out (otherwise a got a mysterious (to me) error,
when using joined inheritance at the same time).
This solution is key to my datamodel. Does anyone see any drawbacks?
Cheers, Lars
On Feb 5, 10:50 am, Gaëtan de Menten <gdemen...@gmail.com> wrote:
> On 02/03/2012 12:08 PM, lars van gemerden wrote:
>
>
>
>
>
>
>
> > I should probably make the pair method:
>
> > def pair(name1, name2):
> > p1, p2 = Pairs(name1), Pairs(name2)
> > p1.other = p2
> > p2.other = p1
>
> > On Feb 3, 11:57 am, lars van gemerden<l...@rational-it.com> wrote:
> >> Hi, I am trying to sote pairs in a table as follows:
>
> >> #--------------------------------------------------------------------------
> >> ------------
> >> from elixir import *
>
> >> metadata.bind = "sqlite:///:memory:"
> >> metadata.bind.echo = False
>
> >> class Pairs(Entity):
> >> name = Field(String(50), primary_key = True)
> >> other = OneToOne('Pairs', inverse = 'other')
>
> You can't have a OneToOne as inverse for a OneToOne, even less for
> itself. Valid relationship pairs are:
>
> ManyToOne - OneToOne
> ManyToOne - OneToMany
> ManyToMany - ManyToMany
>
> In your case you want:
>
> class Pairs(Entity):
> name = Field(String(50), primary_key = True)
> other1 = ManyToOne('Pairs', inverse = 'other2')
> other2 = OneToOne('Pairs', inverse = 'other1')
>
> and if your database really only stores pairs, a property might make it
> more elegant:
>
> @property
> def other(self):
> return self.other1 if self.other1 is not None else self.other2
>
> As a side note, you probably do not want to use Elixir for a new
> project, as Elixir is not maintained anymore.
>
> -G.
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