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.AdminController 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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