You need to use argument post_update=True on your thumbnails relation
http://www.sqlalchemy.org/docs/05/mappers.html#rows-that-point-to-themselves-mutually-dependent-rows <http://www.sqlalchemy.org/docs/05/mappers.html#rows-that-point-to-themselves-mutually-dependent-rows>Here is a sample I used that seems to work. Interesting is that you cannot create the tables with meta.create_all() because of te circular dependency. I created the table in 2 separate calls. class Image(Base): __tablename__='image' id = Column(Integer, primary_key=True) project_id = Column(Integer, ForeignKey('project.id')) def __repr__(self): return "<I> id:%s" % self.id class Project(Base): __tablename__='project' id = Column(Integer, primary_key=True) thumbnail_id = Column(Integer, ForeignKey('image.id') ) images = relation('Image', backref=backref('project'), primaryjoin="Project.id==Image.project_id", foreign_keys=[Image.project_id] ) thumbnail = relation(Image, primaryjoin="Project.thumbnail_id==Image.id", foreign_keys=[thumbnail_id], uselist=False, post_update=True) def __repr__(self): return "<P> id:%s thumb:%s" % (self.id, self.thumbnail_id) Image.__table__.create() Project.__table__.create() P1 = Project() I1 = Image() I2 = Image() I3 = Image() P1.images.extend([I1,I2,I3]) P1.thumbnail=I2 session.add(P1) session.flush() --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
