请参见下面的工作代码。关键点是我在评论中提到的那些：
- 适当的复合
ForeignKey
小号 relationship
使用FK正确配置
码：
workflows = Table('workflows', base.metadata, Column('id', Integer, primary_key=True), )actions = Table('actions', base.metadata, Column('workflow_id', Integer, ForeignKey(workflows.c.id), primary_key=True), Column('name', String, primary_key=True), )action_dependencies = Table('action_dependencies', base.metadata, Column('workflow_id', Integer, ForeignKey(workflows.c.id), primary_key=True), Column('parent_action', String, ForeignKey(actions.c.name), primary_key=True), Column('child_action', String, ForeignKey(actions.c.name), primary_key=True), ForeignKeyConstraint(['workflow_id', 'parent_action'], ['actions.workflow_id', 'actions.name']), ForeignKeyConstraint(['workflow_id', 'child_action'], ['actions.workflow_id', 'actions.name']), )class Workflow(base): __table__ = workflows actions = relationship("Action", order_by="Action.name", backref="workflow")class Action(base): __table__ = actions children = relationship("Action", secondary=action_dependencies, primaryjoin=and_(actions.c.name == action_dependencies.c.parent_action, actions.c.workflow_id == action_dependencies.c.workflow_id), secondaryjoin=and_(actions.c.name == action_dependencies.c.child_action, actions.c.workflow_id == action_dependencies.c.workflow_id), backref="parents" )# create db schemabase.metadata.create_all(engine)# create entitiesw_1 = Workflow()w_2 = Workflow()a_11 = Action(name="ac-11", workflow=w_1)a_12 = Action(name="ac-12", workflow=w_1)a_21 = Action(name="ac-21", workflow=w_2)a_22 = Action(name="ac-22", workflow=w_2)session.add(w_1)session.add(w_2)a_22.parents.append(a_21)session.commit()session.expunge_all()print '-'*80# helper functionsdef get_workflow(id): return session.query(Workflow).get(id)def get_action(name): return session.query(Action).filter_by(name=name).one()# test another OKa_11 = get_action("ac-11")a_12 = get_action("ac-12")a_11.children.append(a_12)session.commit()session.expunge_all()print '-'*80# test KO (THIS SHOULD FAIL VIOLATING FK-constraint)a_11 = get_action("ac-11")a_22 = get_action("ac-22")a_11.children.append(a_22)session.commit()session.expunge_all()print '-'*80
