On 11/24/2015 06:14 PM, Christopher Lee wrote:
>
> I am having a problem with SQLAlchemy 1.0.9 that cropped up when I
> upgraded from 0.8.
this is a nicely written test but I get the same recursion overflow
error when I run it in 0.8, 0.9, and 1.0, even back in 0.8.3. Can you
provide a script that illustrates success in 0.8 and not in 1.0 ? thanks.
>
> I have the following polymorphic relationship defined. For some reason,
> when I build a tree, and I try to access the children of the middle node
> of the tree, it is picking up the wrong edge object and going into a
> recursive loop. (Querying for the children of n2 is picking up the edge
> e12, instead of the edges e23, e24 and e25.)
>
> Looking at the identity map, it looks like the query isn't populating
> the correct objects.
>
> If I move the "links" relationship from the NodesWithEdges class to the
> base Node class, the query works fine. Also, if I drop join_depth or
> remove with with_polymorphic mapper arg, it forces multiple queries, and
> the problem doesn't occur. Is this a bug with the new release, or am I
> doing something bad?
>
>
> from __future__ import print_function, unicode_literals
>
> import sqlalchemy as sa
> import sqlalchemy.orm
> import sqlalchemy.ext.associationproxy
> import sqlalchemy.ext.declarative
> import sqlalchemy.ext.orderinglist
>
> Base = sqlalchemy.ext.declarative.declarative_base()
>
>
> class Node(Base):
> __tablename__ = 'todo_elements'
>
> element_id = sa.Column(sa.Integer, nullable=False, primary_key=True)
> element_type = sa.Column(sa.String(20), nullable=False)
>
> __mapper_args__ = {
> 'polymorphic_on': element_type,
> 'with_polymorphic': ('*', None),
> }
>
>
> class NodeWithEdges(Node):
> __mapper_args__ = {'polymorphic_identity': 'todo.list'}
>
>
> class LeafNode(Node):
> __mapper_args__ = {'polymorphic_identity': 'todo.item'}
>
> my_flag = sa.Column(sa.Boolean, default=False)
>
>
> class Edge(Base):
> __tablename__ = 'todo_links'
> __table_args__ = (
> sa.PrimaryKeyConstraint('parent_id', 'child_id'),
> sa.ForeignKeyConstraint(['parent_id'], [Node.element_id]),
> sa.ForeignKeyConstraint(['child_id'], [Node.element_id]),
> )
>
> parent_id = sa.Column(sa.Integer, nullable=False)
> child_id = sa.Column(sa.Integer, nullable=False)
>
>
> Edge.child = sa.orm.relationship(
> Node,
> uselist=False,
> primaryjoin=Edge.child_id == Node.element_id,
> lazy=False,
> cascade='all',
> passive_updates=False,
> join_depth=8,
> )
>
>
> NodeWithEdges.links = sa.orm.relationship(
> Edge,
> primaryjoin=NodeWithEdges.element_id == Edge.parent_id,
> lazy=False,
> cascade='all, delete-orphan',
> single_parent=True,
> passive_updates=False,
> join_depth=8,
> )
>
> NodeWithEdges.children = sa.ext.associationproxy.association_proxy(
> 'links', 'child',
> creator=lambda child: Edge(child_id=child.element_id))
>
>
>
> engine = sa.create_engine('sqlite:///:memory:', echo=True)
> Base.metadata.create_all(engine)
>
> Session = sa.orm.sessionmaker(bind=engine)
> session = Session()
>
>
> #
> # 1 --> 2 --> 3
> # --> 4
> # --> 5
> #
>
> n1 = NodeWithEdges(element_id=1)
> n2 = NodeWithEdges(element_id=2)
> n3 = LeafNode(element_id=3)
> n4 = LeafNode(element_id=4, my_flag=True)
> n5 = LeafNode(element_id=5)
>
> e12 = Edge(parent_id=n1.element_id, child_id=n2.element_id)
> e23 = Edge(parent_id=n2.element_id, child_id=n3.element_id)
> e24 = Edge(parent_id=n2.element_id, child_id=n4.element_id)
> e25 = Edge(parent_id=n2.element_id, child_id=n5.element_id)
>
> session.add_all([n1, n2, n3, n4, n5, e12, e23, e24, e25])
> session.commit()
> session.expunge_all()
>
> new_n1 =
> session.query(NodeWithEdges).filter(NodeWithEdges.element_id==1).first()
> print(session.identity_map.keys())
>
>
> def traverse(node, f, depth=0):
> f(node, depth)
> if hasattr(node, 'children'):
> for c in node.children:
> traverse(c, f, depth + 1)
>
> def indent_print(node, depth):
> print(' ' * depth + str(node.element_id))
> if hasattr(node, 'my_flag'):
> print(node.my_flag)
>
> traverse(new_n1, indent_print)
>
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