I apologize if this is well trodden ground, but having googled, and
stack-overflowed, read the docs, and searched this list, where lots of
people have asked the same (or similar) questions, I couldn't find a
concrete answer...
I'm trying to set up a Model such that an entry can be connected to one or
more other entries, and that the reverse relationship can be found from the
same attribute.
Effectively I'm trying to do this:
```
from sqlalchemy import Integer, ForeignKey, String, Column, Tablefrom
sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy.orm import
relationship
Base = declarative_base()
node_to_node = Table("node_to_node", Base.metadata,
Column("left_node_id", Integer, ForeignKey("node.id"), primary_key=True),
Column("right_node_id", Integer, ForeignKey("node.id"), primary_key=True))
class Node(Base):
__tablename__ = 'node'
id = Column(Integer, primary_key=True)
label = Column(String)
connected = relationship("Node",
secondary=node_to_node,
primaryjoin=id==node_to_node.c.left_node_id,
secondaryjoin=id==node_to_node.c.right_node_id,
backref="connected"
)
```
However, that naturally fails (`Error creating backref 'translations' on
relationship 'Sentence.translations': property of that name exists`) as
there's no magic to figure out that `translations` should be
bi-directional.
Is there another way to achieve this?
Thanks!
Matt.
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