Michael,
Thank you,
reading trough your example (and running it)
made me understand a bit more how SQLA works.
I managed to get it all working,
Since I was on my way to something a bit slightly more complex ...one last
Question
What if I would like to:
Class RelationType(Base):
__tablename__ = 'relationtypes'
Id = Column(Integer,
primary_key=True)
ChildRelationType = Column(Unicode(20))
ParentRelationType = Column(Unicode(20))
Some data for information:
Id ChildRelationType
ParentRelationType
1 "Parent"
"Child"
2 "Supplier"
"Customer"
I will put additional logic to print Mother - Son, in Fact this is not really
what I am doing but I feel the need to make it a bit more understandable for
the MailingList
At the end it will be something with molecules, not really interesting and easy
to understand.
>
> relation_table = Table('relation', Base.metadata,
> Column('rid', Integer, ForeignKey('affiliations.id'), primary_key=True),
Column('RelationType', integer, ForeignKey('relationtypes.Id')),
> Column('lid', Integer, ForeignKey('affiliations.id'), primary_key=True),
> )
Adding this column to the relation_table does not make a difference but....
Somehow I need to get a reference to the "type of relation"
Setting the relation_type MUST be done whilst "Appending" it. i.e. every
relation between "Affiliates" must have a reason
Is this possible or is there another way to do such a thing, I feel logically
it should be part of the relation_table.
Thank you Again for your great help. I'm Not really good in Database stuff, but
did/do a lot on the mod_python/mod_wsgi lists so I know about the huge amounts
of time spent....
Martijn
On Jan 4, 2011, at 7:20 PM, Michael Bayer wrote:
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import declarative_base
>
> Base = declarative_base()
>
> relation_table = Table('relation', Base.metadata,
> Column('rid', Integer, ForeignKey('affiliations.id'), primary_key=True),
> Column('lid', Integer, ForeignKey('affiliations.id'), primary_key=True),
> )
>
> class Affiliation(Base):
> __tablename__ = "affiliations"
> id = Column(Integer, primary_key=True)
> discriminator = Column('type', Unicode(20))
> __mapper_args__ = {'polymorphic_on': discriminator}
>
> ParentRelation = relation(
> 'Affiliation',
> primaryjoin=relation_table.c.rid==id,
> secondaryjoin=relation_table.c.lid==id,
> secondary=relation_table,
> backref="ChildRelation")
>
> class Person(Affiliation):
> __tablename__ = 'persons'
> id = Column(Integer, ForeignKey('affiliations.id'), primary_key=True)
> __mapper_args__ = {'polymorphic_identity':'person'}
>
> class Company(Affiliation):
> __tablename__ = 'companies'
> id = Column(Integer, ForeignKey('affiliations.id'), primary_key=True)
> __mapper_args__ = {'polymorphic_identity':'company'}
>
> e = create_engine('sqlite://', echo =True)
> Base.metadata.create_all(e)
> sess = Session(e)
>
> p1, p2, c1, c2 = Person(), Person(), Company(), Company()
>
> p1.ParentRelation.append(c1)
> p1.ChildRelation.append(c2)
> c1.ParentRelation.append(p2)
> c2.ChildRelation.append(p1)
>
> sess.add_all([p1, p2, c1, c2])
> sess.commit()
--
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 at
http://groups.google.com/group/sqlalchemy?hl=en.
