this is something related to how turbogears is integrating
SQLAlchemy. there might be a bug in SA here but I cant track it down
without an example that shows what TG is doing more specifically. in
particular i hope they are using the QueuePool connection pool and
not the SingletonThreadPool....the error involves a cursor being
shared between two conflicting states.
On Feb 20, 2007, at 10:12 AM, Brad Lindsay wrote:
> I'm new to SQLAlchemy, and am currently using it for Turbogears
> developement. I've run into an issue calling delete on an
> instance. This almost exact same code works fine in one of my
> projects, but I get an error in this particular one. I think it
> may have be because this is a many-to-many relationship while the
> other one is simply a many-to-one relationship. I think there's
> something I'm missing, and was hoping someone might be able to see
> what it was.
>
> Thanks,
> Brad
>
> Here's the setup:
> ===================
> questions_table = Table('questions', metadata,
> Column('id', Integer, primary_key=True),
> Column('interrogative', Unicode(255), nullable=False),
> Column('sort_order', Integer, nullable=False, default=0)
> )
>
> choices_table = Table('choices', metadata,
> Column('id', Integer, primary_key=True),
> Column('a_choice', Unicode(255), nullable=False)
> )
>
> choices_questions_table = Table('choices_questions', metadata,
> Column('question_id', Integer, ForeignKey('questions.id')),
> Column('choice_id', Integer, ForeignKey(' choices.id'))
> )
>
> class Question(object):
> """The Question class."""
> def __init__(self, interrogative, order):
> self.interrogative = interrogative
> self.sort_order = order
>
> class Choice(object):
> """The Choice class."""
> def __init__(self, a_choice):
> self.a_choice = a_choice
>
> assign_mapper(session.context, Question, questions_table,
> properties=dict(choices=relation(Choice,
> secondary=choices_questions_table, backref='questions')))
>
> assign_mapper(session.context, Choice, choices_table)
>
>
> Here's the function that's having problems:
> ======================================
> def q_delete(self, qid):
> del_q = Question.get(int(qid))
> Question.delete(del_q)
> raise redirect("/admin")
>
>
> Here's the error:
> =====================
> Page handler: <bound method AdminController.q_delete of
> <neognosis.controllers.AdminCont
> roller object at 0x2151490>>
> Traceback (most recent call last):
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/CherryPy- 2.2.1-py2.4.egg/cherrypy/
> _cphttptools.py", line 105, in _run
> self.main()
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/CherryPy-2.2.1-py2.4.egg/cherrypy/
> _cphttptools.py", line 254, in main
> body = page_handler(*virtual_path, **self.params)
> File "<string>", line 3, in q_delete
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/TurboGears- 1.0-py2.4.egg/turbogears/
> controllers.py", line 334, in expose
> output = database.run_with_transaction(
> File "<string>", line 5, in run_with_transaction
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/TurboGears- 1.0-py2.4.egg/turbogears/
> database.py", line 305, in sa_rwt
> retval = dispatch_exception(e,args,kw)
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/TurboGears-1.0-py2.4.egg /turbogears/
> database.py", line 303, in sa_rwt
> transaction.commit()
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/session.py",
> line 54, in commit
> File "build/bdist.macosx-10.3-fat /egg/sqlalchemy/orm/
> session.py", line 220, in flush
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> unitofwork.py", line 194, in flush
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> unitofwork.py", line 321, in execute
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> unitofwork.py", line 771, in preexecute
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> dependency.py", line 176, in preprocess_dependencies
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> dependency.py", line 99, in get_object_dependencies
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> attributes.py", line 686, in get_history
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> attributes.py", line 85, in get_history
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/
> attributes.py", line 183, in get
> File "build/bdist.macosx- 10.3-fat/egg/sqlalchemy/orm/
> strategies.py", line 220, in lazyload
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/query.py",
> line 254, in select_whereclause
> File "build/bdist.macosx-10.3-fat /egg/sqlalchemy/orm/query.py",
> line 380, in _select_statement
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/query.py",
> line 312, in execute
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/orm/query.py",
> line 330, in instances
> File "build/bdist.macosx-10.3-fat/egg/sqlalchemy/engine/base.py",
> line 671, in fetchall
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/MySQLdb/cursors.py", line 258, in fetchall
> self._check_executed()
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/MySQLdb/cursors.py", line 54, in
> _check_executed
> self.errorhandler(self, ProgrammingError, "execute() first")
> File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
> python2.4/site-packages/MySQLdb/connections.py", line 33, in
> defaulterrorhandler
> raise errorclass, errorvalue
> ProgrammingError: execute() first
>
> >
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