I'm trying to use the object association pattern from the doco. Is it
the case that this requires departure from Declarative mode and is it
wrong to mix with non-declarative? I looked at the example code
optimized_al.py but it didn't seem to be exactly what I want. I want a
symmetric relation for adjacency of nodes in an undirected graph with
cycles. ie. it is not a tree.
<code>
class Node(DeclarativeBase):
__tablename__ = 'node'
#with some columns id etc.
adj = Table(u'adj', metadata,
Column(u'node', Integer(), ForeignKey('node.id'),
primary_key=True),
Column(u'adj_node', Integer(), ForeignKey('node.id'),
primary_key=True),
Column(u'somedata_id', Integer(), ForeignKey('somedata.id')),
)
class Adj(object):
__table__ = _adj
#relation definitions
node = relation('node') # self-referential, bidirectional, many-
to-many
somedata = relation('SomeData')
def __init__(self, n1, n2):
self.n1 = n1
self.n2 = n2
mapper(Adj, adj, properties={
'node': relation(Adj,
primaryjoin = Node.id==Adj.node,
#secondaryjoin = Node.id==Adj.adj_node?,
backref=backref('adj_node',
remoteside=[_adj.c.node])
)
}, non_primary=True)
</code>
I put the non_primary and the primaryjoin in after error messages told
me to but now this is causing another error 'Adj' has not attribute
'node' I even tried primaryjoin = Node.id==adj.c.node but then I got
"Could not locate any equated, locally mapped column pairs." This
seems to be getting a bit more complicated than it should be already.
Is there an example of an association object in Declarative style?
Also, is it possible to do it with forward references only?
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