Here's the issue, boiled down to one file. On import, the last statement
fails, mapping the Connections object. I just need to map two relations on an
association object (Connections) to a polymorphic union (NetworkNode). Is
there a way to do this?
sqlalchemy.exc.ArgumentError: Column 'network_nodes.node_id' is not represented
in mapper's table. Use the `column_property()` function to force this column
to be mapped as a read-only attribute.
from sqlalchemy import *
from sqlalchemy import sql
from sqlalchemy import orm
metadata = MetaData()
tbl1 = Table("source_sink",metadata,
Column("node_id",Integer,primary_key=True),
Column("source_sink_name",String(60),nullable=False),
Column("source_or_sink",String(6)))
tbl2 = Table("meas_type_a",metadata,
Column("node_id",Integer,primary_key=True),
Column("meas_point_name",String(60),nullable=False),
Column("subtype",String(10)),
Column("latitude",Numeric(precision=12,scale=9,asdecimal=True)),
Column("longitude",Numeric(precision=12,scale=9,asdecimal=True)))
tbl3 = Table("meas_type_b",metadata,
Column("node_id",Integer,primary_key=True),
Column("meas_point_name",String(60),nullable=False),
Column("subtype",String(10)),
Column("latitude",Numeric(precision=12,scale=9,asdecimal=True)),
Column("longitude",Numeric(precision=12,scale=9,asdecimal=True)),
Column("capacity",Numeric(precision=6,scale=2,asdecimal=True)))
tbl4 = Table("meas_type_c",metadata,
Column("node_id",Integer,primary_key=True),
Column("meas_point_name",String(60),nullable=False),
Column("subtype",String(10)),
Column("latitude",Numeric(precision=12,scale=9,asdecimal=True)),
Column("longitude",Numeric(precision=12,scale=9,asdecimal=True)),
Column("stringuserfield1",String(40)),
Column("numericuserfield1",Numeric(precision=6,scale=2,asdecimal=True)))
nn = orm.util.polymorphic_union({1:tbl1,2:tbl2,3:tbl3,4:tbl4},
"node_type","network_nodes")
cnct = Table("connections",metadata,
Column("upstream_id",Integer,primary_key=True),
Column("upstream_type",Integer,primary_key=True),
Column("downstream_id",Integer,primary_key=True),
Column("downstream_type",Integer,primary_key=True),
Column("effective_date",DateTime(timezone=False)),
Column("expiration_date",DateTime(timezone=False)))
class NetworkNode(object):
pass
nnmapper = orm.mapper(NetworkNode,nn,primary_key=[nn.c.node_id,nn.c.node_type],
with_polymorphic=('*',nn),polymorphic_on=nn.c.node_type)
class SourceSinkNode(NetworkNode):
pass
ss =
orm.mapper(SourceSinkNode,tbl1,inherits=nnmapper,polymorphic_identity=1,concrete=True)
class MeasTypeA(NetworkNode):
pass
ma =
orm.mapper(MeasTypeA,tbl2,inherits=nnmapper,polymorphic_identity=2,concrete=True)
class MeasTypeB(NetworkNode):
pass
mb =
orm.mapper(MeasTypeB,tbl3,inherits=nnmapper,polymorphic_identity=3,concrete=True)
class MeasTypeC(NetworkNode):
pass
mc =
orm.mapper(MeasTypeC,tbl4,inherits=nnmapper,polymorphic_identity=4,concrete=True)
class Connection(NetworkNode):
pass
connmapper = orm.mapper(Connection,cnct,properties=dict(
upstreamnodes=orm.relation(NetworkNode,primaryjoin=
and_(cnct.c.downstream_id==nn.c.node_id,
cnct.c.downstream_type==nn.c.node_type),
foreign_keys=[nn.c.node_id,nn.c.node_type]),
downstreamnodes=orm.relation(NetworkNode,primaryjoin=
and_(cnct.c.upstream_id==nn.c.node_id,
cnct.c.upstream_type==nn.c.node_type)),
foreign_keys=[nn.c.node_id,nn.c.node_type]))
Wes Dyk
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