Update, (Still need help, I'm really puzzled on how to do this)
since both Person and Company are polymorphic from Affiliation the relations
are not really self referencing,
So I need help defining the relation and a reference table. The reference table
should however be something like this:
TablenameL LId TablenameR Rid
person 1 company 2
company 2 person 3
So the reference table "relations" should have a compound key "person:1" to
connect to "company:2"
at the same time "company:2" should connect to "person:3"
I would like to add something like this to my Affiliation class:
relationships =
relation(Relation,primaryjoin=or_(and_(Relation.LTable==discriminator,Relation.LId
==Id),and_(Relation.RTable==discriminator,Relation.RId==Id)))
I know this is wrong but the reference table should also work backwards. There
will also be an Relationtype indicating
Company->employee->Person,
Company->customer->Person
Person->friend-Person
etc. (one Company can have many relations to the same Person, like Companies
can have multiple relations with other companies (like "supplier", "customer",
"partner (like in a project)" etc. etc)
also Person1->Father->Person2 will be Person2->Son->Person1 when lookup the
other way around. the Relationtype will be a ForeignKey to another table, the
"Order" will be dependent on the "side" of the (current object) Person so there
might be two relations in the Affiliation object . One working on the "Left"
side of the reference table and the other one from the "Right"
This is just a small piece, in total there are many Classes based on the
Affiliation object so doing it all there would be nice....
Thanks for ANY thoughts, doing this right from the beginning helps me a lot.
The definition of Affiliation, Person and Company can be found below.
Martijn
On Jan 4, 2011, at 9:55 AM, Martijn Moeling wrote:
> Hi
>
> I have done the following:
>
>
> class Affiliation(Base):
> __tablename__ = "affiliations"
> Id = Column(Integer, primary_key=True)
> FullName = Column(Unicode(255), index = True)
> discriminator = Column('type', Unicode(20))
> __mapper_args__ = {'polymorphic_on': discriminator}
>
>
> class Person(Affiliation):
> __tablename__ = 'persons'
> __mapper_args__ = {'polymorphic_identity' : u'person'}
> Id = Column(Integer,ForeignKey('affiliations.Id'),
> primary_key=True)
>
>
> class Company(Affiliation):
> __tablename__ = 'companies'
> __mapper_args__ = {'polymorphic_identity' : u'company'}
> Id = Column(Integer,ForeignKey('affiliations.Id'),
> primary_key=True)
>
> which is straight foreward.
>
> What I want do do now is a bit more troublesome, I have been trying many
> different things but....
>
> class relation(Base):
>
> Parent = reference to one of the Affiliations
> Child = reference to one of the Affiliations
> Relation_type = column(Integer) (like two
> persons can be Father and Son, Two companies can be supplier and customer)
>
>
> It would be very nice if I can change the Affiliation class to self reference
> M:N
>
> Problem with this is that both Parent and child (or "left and right "side")
> have to be checked and updated
>
> Martijn
>
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