Let me prefix this by saying that I am a newbie to SA, though not to
ORMs in general. So far I've really enjoyed using SA: its an amazing
package for working with databases.
Presently I am trying to create a GM tool for Shadowrun 4th Edition,
where I am trying to model this concept called a "Data Bomb." The
Data Bomb works by detonating and doing damage to the hacker and then
potentially deleting the file it sits on. There is also some
associated metadata that I would like to store, so I have modeled the
data bombs as being in a separate table from the files. The database
is currently sqlite, but I may switch later to another system that is
a little more robust at a later date.
The system is MacOS X 10.4.10, Python 2.5.1 Stackless 3.1b3 060516
(python-2.51:55546, May 24 2007, 08:50:09). I am calling the
following from inside of a unit test, and no tasklets or threads of
any sort are involved in this part of the app.
When I attempt to delete an object it generates an exception and then
appears to corrupt the session, such that further save statements
generate the same exception.
These are the table definitions I am presently using:
file_table = Table('files', dbutil.metadata,
Column('id', Integer, primary_key=True),
Column('securable_id', Integer,
ForeignKey('securable.id')),
Column('node_id', Integer, ForeignKey('nodes.id')),
Column('name', String(32), nullable=False),
Column('content', String(), nullable=False),
Column('version', Integer),
Column('encryption', Integer, default=0)
)
bomb_table = Table('data_bombs', dbutil.metadata,
Column('id', Integer, primary_key=True),
Column('name', String(16), default="None"),
Column('strength', Integer,
CheckConstraint('strength >= 0'), nullable=False),
Column('destroy_chance', Float(2), nullable=False),
Column('file_id', Integer, ForeignKey('files.id'),
unique=True),
Column('version', Integer)
)
The mapper calls:
mapper(DataBomb, bomb_table, version_id_col='version',
properties={
'file':relation(File, backref='bomb')
})
mapper(File, file_table, version_id_col='version', inherits=Securable,
polymorphic_identity='file',
properties={
'node':relation(node.Node, backref='files',
primaryjoin=node.node_table.c.id == file_table.c.node_id)
}
)
The classes are right now just acting as data stores with a few
utility functions. The data bomb takes the file as an argument when
it is being created.
I have created a DAO for both tables, but for the sake of debugging I
have moved the pieces generating the error out into the test
function. The DAO uses the "with" statement with begin_nested().
The first unit test that is running:
* Creates a file
* Creates a data bomb that is associated to that file.
* Deletes the data bomb in a separate transaction.
The code for the test is as follows:
def testBomb(self):
session = dbutil.create_session()
filetest = file_dao.create('green', 'maho')
bomb = bomb_dao.create(filetest, 10)
with session.begin():
session.delete(bomb)
When it flushes/commits after the deletion, it generates the
following:
======================================================================
ERROR: testBomb (nodefile.FileTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/raven/Documents/AoW/workspace/ShadowMatrix/src/
shadowmatrix/model/nodefile.py", line 172, in testBomb
session.delete(bomb)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 256, in __exit__
self.commit()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 211, in commit
self.session.flush()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 665, in flush
self.uow.flush(self, objects)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 202, in flush
flush_context.execute()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 414, in execute
UOWExecutor().execute(self, head)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1056, in execute_delete_steps
self.execute_childtasks(trans, task, True)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1070, in execute_childtasks
self.execute(trans, child, isdelete)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1056, in execute_delete_steps
self.execute_childtasks(trans, task, True)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1070, in execute_childtasks
self.execute(trans, child, isdelete)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1058, in execute_delete_steps
self.delete_objects(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1041, in delete_objects
task.mapper.delete_obj(task.polymorphic_todelete_objects, trans)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 1253, in delete_obj
params[mapper.version_id_col.key] = mapper.get_attr_by_column(obj,
mapper.version_id_col)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 949, in get_attr_by_column
prop = self._getpropbycolumn(column, raiseerror)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 933, in _getpropbycolumn
prop = self.columntoproperty[column]
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
util.py", line 101, in __getitem__
return super(TranslatingDict,
self).__getitem__(self.__translate_col(col))
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
util.py", line 94, in __translate_col
ourcol = self.selectable.corresponding_column(col, keys_ok=False,
raiseerr=False)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/sql/
expression.py", line 1605, in corresponding_column
for c in column.orig_set:
AttributeError: 'str' object has no attribute 'orig_set'
The second test that runs just generates the file, retrieves it by
name, and then makes sure that name is the same coming out as it is
going in:
def testCreate(self):
file_dao.create('purple', 'foo')
filetest = file_dao.get('purple')
self.assertEqual(filetest.name, 'purple')
After the prior testBomb runs, it generates the following error:
======================================================================
ERROR: testCreate (nodefile.FileTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/raven/Documents/AoW/workspace/ShadowMatrix/src/
shadowmatrix/model/nodefile.py", line 149, in testCreate
file_dao.create('purple', 'foo')
File "/Users/raven/Documents/AoW/workspace/ShadowMatrix/src/
shadowmatrix/database/dao.py", line 60, in create
session.save(obj)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 256, in __exit__
self.commit()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 211, in commit
self.session.flush()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
session.py", line 665, in flush
self.uow.flush(self, objects)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 202, in flush
flush_context.execute()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 414, in execute
UOWExecutor().execute(self, head)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1056, in execute_delete_steps
self.execute_childtasks(trans, task, True)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1070, in execute_childtasks
self.execute(trans, child, isdelete)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1056, in execute_delete_steps
self.execute_childtasks(trans, task, True)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1070, in execute_childtasks
self.execute(trans, child, isdelete)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1035, in execute
self.execute_delete_steps(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1058, in execute_delete_steps
self.delete_objects(trans, task)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
unitofwork.py", line 1041, in delete_objects
task.mapper.delete_obj(task.polymorphic_todelete_objects, trans)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 1253, in delete_obj
params[mapper.version_id_col.key] = mapper.get_attr_by_column(obj,
mapper.version_id_col)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 949, in get_attr_by_column
prop = self._getpropbycolumn(column, raiseerror)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
mapper.py", line 933, in _getpropbycolumn
prop = self.columntoproperty[column]
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
util.py", line 101, in __getitem__
return super(TranslatingDict,
self).__getitem__(self.__translate_col(col))
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/orm/
util.py", line 94, in __translate_col
ourcol = self.selectable.corresponding_column(col, keys_ok=False,
raiseerr=False)
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/
python2.5/site-packages/SQLAlchemy-0.4.0beta4-py2.5.egg/sqlalchemy/sql/
expression.py", line 1605, in corresponding_column
for c in column.orig_set:
AttributeError: 'str' object has no attribute 'orig_set'
If I reverse the order, changing the name of testBomb to testDataBomb,
testCreate will run correctly, but testDataBomb will generate the
same error as above.
testCreate (nodefile.FileTests) ... ok
testDataBomb (nodefile.FileTests) ... ERROR
Any ideas? Any help is appreciated.
Sincerely,
David
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