python - One-to-one self-referential relationship using an association table in SqlAlchemy -

so have parent child relationship between topic models relationship represented class:

class parentchildrelation(db.model):     __tablename__ = 'parent_child_relation'      id = db.column(db.integer, primary_key=true)     child_topic_id = db.column(db.integer, db.foreignkey('topic.id'), nullable=false)     parent_topic_id = db.column(db.integer, db.foreignkey('topic.id'), nullable=false) 

and topics defined such:

class topic(db.model):     __tablename__ = 'topic'      id = db.column(db.integer, primary_key=true)      parent = db.relationship(         'topic',         secondary='parent_child_relation',         primaryjoin='topic.id == parentchildrelation.child_topic_id',         secondaryjoin='topic.id == parentchildrelation.parent_topic_id'     ) 

i'd have parent one-to-one relationship (i might change later on), comes instrumentedlist. there simple way of stating parent should one-to-one relationship such links directly topic model instead of being instrumentedlist?

so turns out had found correct answer, must have had typo :/. adding uselist=false did trick.

parent = db.relationship(     'topic',     secondary='parent_child_relation',     primaryjoin='topic.id == parentchildrelation.child_topic_id',     secondaryjoin='topic.id == parentchildrelation.parent_topic_id',     uselist=false )