的SQLAlchemy：ValueError异常

Question

我有这些表： 1）用户

class User(Base): 
    __tablename__ = 'users' 
    id = Column(Integer, primary_key = True) 
    fname = Column(String(45)) 
    lname = Column(String(45)) 
    mail = Column(String(45)) 
    password = Column(String(45)) 

    courses = relationship("Course", secondary=user_course, backref="users") 
    universities = relationship("University", secondary=user_university, backref="users") 

    def add_university(self, university): 
     universities = self.universities 
     universities.append(university) 
     self.universities = universities 

    def add_course(self, course): 
     courses = self.courses 
     courses.append(course) 
     self.courses = courses 

2）大学

class University(Base): 
    __tablename__ = 'universities' 
    id = Column(Integer, primary_key=True) 
    date = Column(DateTime) 
    name = Column(String(45)) 

3）课程

class Course(Event): 
    __tablename__ = 'courses' 
    id = Column(Integer, ForeignKey('events.id'), primary_key=True) 
    name = Column(String(45)) 
    year = Column(Integer) 

    __mapper_args__ = { 
     'polymorphic_identity':'course', 
    } 

    events = relationship("Event", secondary=course_event, backref="courses") 

所以一个多对多到许多与用户课程和用户大学，以及许多课程活动（当然还有家长）。

当我尝试添加我的方法一所大学的在用户定义它的工作原理，但是当我尝试添加一门课程我得到这个错误：

回溯（最近通话最后一个）：

File "/Users/arnoutaertgeerts/Documents/Eclips/SlideTalk 2.0/test_SQL.py", line 473, in <module> 
    arnout.add_course(Analyse) 
    File "/Users/arnoutaertgeerts/Documents/Eclips/SlideTalk 2.0/test_SQL.py", line 101, in add_course 
    courses.append(course) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 1046, in append 
    item = __set(self, item, _sa_initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 1021, in __set 
    item = getattr(executor, 'fire_append_event')(item, _sa_initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 714, in fire_append_event 
    item, initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 800, in fire_append_event 
    value = fn(state, value, initiator or self) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 1026, in emit_backref_from_collection_append_event 
    passive=PASSIVE_NO_FETCH) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 854, in append 
    collection.append_with_event(value, initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 655, in append_with_event 
    getattr(self._data(), '_sa_appender')(item, _sa_initiator=initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 1046, in append 
    item = __set(self, item, _sa_initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 1021, in __set 
    item = getattr(executor, 'fire_append_event')(item, _sa_initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/collections.py", line 714, in fire_append_event 
    item, initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 800, in fire_append_event 
    value = fn(state, value, initiator or self) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 1020, in emit_backref_from_collection_append_event 
    _acceptable_key_err(state, initiator) 
    File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/SQLAlchemy-0.7.9-py2.7.egg/sqlalchemy/orm/attributes.py", line 982, in _acceptable_key_err 
    manager_of_class(initiator.class_)[initiator.key])) 

ValueError异常：对象不是类型的属性相关联User.courses

但是，如果我停下让课程从事件继承，它的工作！

任何想法？

Answer 1

问题解决了！这里是票：http://sqlalchemy.org/trac/ticket/2674