There are many good examples of implementing many to many via a join table.
I'm not sure if I'm being lazy, or just using this as an opportunity to
learn more sqlalchemy, but I'm trying to implement a shortcut from long a go
I know this approach requires a much slower query but these are tiny tables
and they are cached at application startup, so I'm not concerned with
performance.
I have two tables:
class SuperType(Base):
'''
creates groups of type recs
'''
__tablename__ = 'stp_super_type'
stp_name = Column(String(50), nullable=False)
stp_bit = Column(Integer, nullable=False, unique=True) # holds a
unique bit-val for each record (2,4,8, 16,32, 64, etc)
* types = relationship("Type",*
* order_by="asc(Type.typ_order)",*
*
primaryjoin="SuperType.stp_bit.op('&')(Type.typ_stp_bits)==SuperType.stp_bit",*
* backref="stype"*
* )*
class Type(Base):
'''
types for many other recs throughout the system
'''
__tablename__ = 'typ_type'
typ_name = Column(String(50), nullable=False)
typ_stp_bits = Column(Integer, nullable=False) #
ForeignKey(SuperType.stp_bit)
typ_order = Column(Integer, nullable=False)
"id" is the pkey for each table and is generated in the Base
typ_stp_bits would hold a value such as 38 (2 or 4 or 32) to indicate it
is a child (applicable within) those THREE super-type classes....
Hope that makes sense
How do I properly specify this relationship?
I'm getting a complaint that there is no foreign key defined on the
Type/child table....
Thanks,
D
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
