your relationships are not being set up correctly, since you haven't specified a "foreignkey" parameter on any of them. note that the "root" relationship in the documentation example has a "foreignkey" set on it.
when you say: > node_table.c.parent_id==node_table.c.id the "foreignkey" is automatically going to be "parent_id". but for half of those relationships, you want the "foreignkey" to be "id". the actual ordering of the columns in the comparison is not significant. On Sep 5, 2006, at 10:12 AM, Nick Joyce wrote: > I am attempting to extend the self referential example in the docs > http://www.sqlalchemy.org/docs/index.myt? > paged=no#advdatamapping_circular > by adding properties 'prev_sibling' and 'next_sibling'. (See attached > script) > > When run, the following exception is raised: > > Traceback (most recent call last): > File "tree.py", line 79, in ? > session.flush() > File "build/bdist.linux-i686/egg/sqlalchemy/orm/session.py", line > 234, > in flush > File "build/bdist.linux-i686/egg/sqlalchemy/orm/unitofwork.py", line > 197, in flush > File "build/bdist.linux-i686/egg/sqlalchemy/orm/unitofwork.py", line > 359, in execute > File "build/bdist.linux-i686/egg/sqlalchemy/orm/unitofwork.py", line > 407, in _sort_dependencies > File "build/bdist.linux-i686/egg/sqlalchemy/orm/unitofwork.py", line > 395, in sort_hier > File "build/bdist.linux-i686/egg/sqlalchemy/orm/unitofwork.py", line > 800, in _sort_circular_dependencies > File "build/bdist.linux-i686/egg/sqlalchemy/orm/topological.py", > line > 139, in sort > sqlalchemy.exceptions.FlushError: Circular dependency detected > {<Node(path=first)> (idself=1079711436): {<Node(path=second)> > (idself=1079711468): True, <Node(path=root)> (idself=1079711404): > True}, <Node(path=root)> (idself=1079711404): {<Node(path=second)> > (idself=1079711468): True, <Node(path=first)> (idself=1079711436): > True}, <Node(path=second)> (idself=1079711468): {<Node(path=first)> > (idself=1079711436): True, <Node(path=root)> (idself=1079711404): > True}}[] > > I am doing something wrong? If so can someone point me in the right > direction ... > > Thanks, > > Nick > import sqlalchemy.mods.threadlocal > from sqlalchemy import * > > engine = create_engine('sqlite:///:memory:', echo=True); > metadata = BoundMetaData(engine) > > node_table = Table('node', metadata, > Column('id', Integer, primary_key=True), > Column('path', String(50), nullable=False), > Column('parent_id', Integer, ForeignKey('node.id'), > nullable=True), > Column('prev_sibling_id', Integer, ForeignKey('node.id'), > nullable=True), > Column('next_sibling_id', Integer, ForeignKey('node.id'), > nullable=True) > ) > > class Node(object): > def __init__(self, path=''): > self.path = path > > def has_child_nodes(self): > return len(self.children) == 0 > > def append_child(self, child): > try: > lc = self.children[len(self.children) - 1] > except IndexError, e: > lc = None > > self.children.append(child) > > child.parent = self > > if lc is not None: > lc.next_sibling = child > child.previous_sibling = lc > > def __repr__(self): > return '<Node(path=%s)>' % self.path > > n_mapper = mapper(Node, node_table, properties={ > 'parent': relation( > Node, > lazy=True, > primaryjoin=node_table.c.parent_id==node_table.c.id, > uselist=False > ), > 'children': relation( > Node, > primaryjoin=node_table.c.id==node_table.c.parent_id, > lazy=True, > cascade="all, delete-orphan" > ), > 'previous_sibling': relation( > Node, > primaryjoin=node_table.c.prev_sibling_id==node_table.c.id, > lazy=True, > uselist=False > ), > 'next_sibling': relation( > Node, > primaryjoin=node_table.c.next_sibling_id==node_table.c.id, > lazy=True, > uselist=False > ) > }) > > if __name__ == '__main__': > node_table.create() > > root = Node('root') > first = Node('first') > second = Node('second') > > root.append_child(first) > root.append_child(second) > > print first==second.previous_sibling > > session = objectstore.session > > session.flush() > ---------------------------------------------------------------------- > --- > Using Tomcat but need to do more? Need to support web services, > security? > Get stuff done quickly with pre-integrated technology to make your > job easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache > Geronimo > http://sel.as-us.falkag.net/sel? > cmd=lnk&kid=120709&bid=263057&dat=121642______________________________ > _________________ > Sqlalchemy-users mailing list > Sqlalchemy-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
