Hi everybody, After switching from SQLAlchemy 0.6.5 to 0.7.0 we have observed a problem with such an example code:
(copy at http://ideone.com/WB36Y) ============================================================== # Fails with Python-2.7.1 and SQLAlchemy-0.7.0 # import sqlalchemy import sqlalchemy.ext.declarative Base = sqlalchemy.ext.declarative.declarative_base() class LimitingQuery(sqlalchemy.orm.query.Query): def get(self, ident): # override get() so that the flag is always checked in the # DB as opposed to pulling from the identity map. - this is optional. return sqlalchemy.orm.query.Query.get(self.populate_existing(), ident) def __iter__(self): return sqlalchemy.orm.query.Query.__iter__(self.private()) def private(self): crit = (self._mapper_zero().class_.isDeleted == False) return self.enable_assertions(False).filter(crit) engine = sqlalchemy.create_engine('sqlite:///:memory:', echo = False) session = sqlalchemy.orm.scoped_session( sqlalchemy.orm.sessionmaker( bind = engine, autocommit = False, query_cls = LimitingQuery ) ) Base.metadata.bind = engine class Employee(Base): __tablename__ = "employees" Id = sqlalchemy.Column( sqlalchemy.types.Integer, primary_key=True, autoincrement=True) isDeleted = sqlalchemy.Column( sqlalchemy.types.Boolean(), default = False) name = sqlalchemy.Column(sqlalchemy.types.String(128)) managerId = sqlalchemy.Column(sqlalchemy.types.Integer, sqlalchemy.ForeignKey(Id)) manager = sqlalchemy.orm.relation( 'Employee', backref = sqlalchemy.orm.backref('subordinates', lazy = 'dynamic'), primaryjoin = managerId == Id, remote_side = Id ) Base.metadata.create_all() SteveBallmer = Employee(name = 'Steve Ballmer') CraigMundie = Employee(name = 'Craig Mundie') BillGates = Employee(name = 'Bill Gates') session.add_all((SteveBallmer, CraigMundie, BillGates)) BillGates.subordinates = [SteveBallmer, CraigMundie] # this line: print BillGates.subordinates.count() # raises: # Traceback (most recent call last): # File "count_problem.py", line 60, in <module> # print BillGates.subordinates.count() # File "/home/filip/tefnet/teferp/workspace/tefobjects/lib/python2.7/site-packages/SQLAlchemy-0.7.0-py2.7.egg/sqlalchemy/orm/dynamic.py", line 251, in count # return self._clone(sess).count() # File "/home/filip/tefnet/teferp/workspace/tefobjects/lib/python2.7/site-packages/SQLAlchemy-0.7.0-py2.7.egg/sqlalchemy/orm/query.py", line 2123, in count # return self.from_self(col).scalar() # File "/home/filip/tefnet/teferp/workspace/tefobjects/lib/python2.7/site-packages/SQLAlchemy-0.7.0-py2.7.egg/sqlalchemy/orm/query.py", line 1775, in scalar # ret = self.one() # File "/home/filip/tefnet/teferp/workspace/tefobjects/lib/python2.7/site-packages/SQLAlchemy-0.7.0-py2.7.egg/sqlalchemy/orm/query.py", line 1744, in one # ret = list(self) # File "count_problem.py", line 17, in __iter__ # return sqlalchemy.orm.query.Query.__iter__(self.private()) # File "count_problem.py", line 20, in private # crit = (self._mapper_zero().class_.isDeleted == False) # AttributeError: 'NoneType' object has no attribute 'class_' ============================================================== As far as I could debug it the problem starts when count() creates a new query with the old one as a subquery (but I could very well be wrong). A similar recipe can be found here: http://www.sqlalchemy.org/trac/wiki/UsageRecipes/PreFilteredQuery Could you give me a hint about a proper way to do this? regards, Filip Zyzniewski Tefnet -- 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.
