Hi,
i'm trying to understand how to cope with errors from the database and I
don't completely understand the following behaviour.
I try to delete a Project that has integrity constrains, so correctly the
db complains and SA raises an OperationalError. Right now I'm not trying
to understand how to *prevent* this. I just want to understand how to give
a message to the user and restore a working situation.
[I'm working with postgreSQL and SA 5.0rc4]
def delete_obj(obj):
print "### deleting obj", repr(obj)
try:
session.delete(obj)
print "session.delete:", session.deleted
session.commit()
except Exception, e:
print "Problemi...", e.message
session.rollback()
q = session.query(Project)
prj = q.filter_by(id=18).one()
print repr(prj)
delete_obj(prj)
print "session.delete:", session.deleted
for obj in session:
print "obj", hex(id(obj)), type(obj)
print "Project", prj ### <<<<<<< this code raises the Interface error
where is the problem? the connection (as I tend to believe) or the object
'prj'?
What's the state in which is now the object 'prj'? What should I do to
go back to the previous situation?
What exacltly means InterfaceError - connection already closed. I simply
issued a .rollback(), why should it be closed? How should I test if a
connection is closed? and how should I open it again?
Thaks in advance
sandro
*:-)
######### OUTPUT ###########
<Project Project 1>
### deleting obj <Project Project 1>
session.delete: IdentitySet([<Project Project 1>])
Problemi... (OperationalError) ERROR: update or delete on table
"ticket_project" violates foreign key constraint
"timereport_report_job_id_fkey" on table "timereport_report"
DETAIL: Key (id)=(18) is still referenced from table "timereport_report".
session.delete: IdentitySet([])
obj 0x88a912c <class 'models.ticket.Project'>
obj 0x88b52cc <class 'models.ticket.Organization'>
obj 0x88b59ec <class 'models.cliente.User'>
No handlers could be found for logger "sqlalchemy.pool.QueuePool.0x...bc2c"
Project Traceback (most recent call last):
File "test.py", line 24, in <module>
print "Project", prj
File "/home/misc/src/hg/py/sqlkit-pub/sqlkit/db/utils.py", line 65, in __str__
format = get_description(self.__table__, attr='format')
File "/home/misc/src/hg/py/sqlkit-pub/sqlkit/db/utils.py", line 226, in
get_description
return getattr(TableDescr(table), attr)
File "/home/misc/src/hg/py/sqlkit-pub/sqlkit/db/utils.py", line 133, in
__init__
self.description, dbformat = self.guess_description()
File "/home/misc/src/hg/py/sqlkit-pub/sqlkit/db/utils.py", line 197, in
guess_description
description, format = get_description_from_sqlkit(table)
File "/home/misc/src/hg/py/sqlkit-pub/sqlkit/db/utils.py", line 240, in
get_description_from_sqlkit
res_proxy = metadata.bind.execute(SQL, table=table.name)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
1202, in execute
return connection.execute(statement, *multiparams, **params)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
824, in execute
return Connection.executors[c](self, object, multiparams, params)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
888, in _execute_text
return self.__execute_context(context)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
896, in __execute_context
self._cursor_execute(context.cursor, context.statement,
context.parameters[0], context=context)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
950, in _cursor_execute
self._handle_dbapi_exception(e, statement, parameters, cursor, context)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
928, in _handle_dbapi_exception
self._autorollback()
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
794, in _autorollback
self._rollback_impl()
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
738, in _rollback_impl
self._handle_dbapi_exception(e, None, None, None, None)
File
"/home/misc/src/sqlalchemy/sqlalchemy-svn/lib/sqlalchemy/engine/base.py", line
912, in _handle_dbapi_exception
raise exc.DBAPIError.instance(None, None, e)
sqlalchemy.exc.InterfaceError: (InterfaceError) connection already closed None
None
--
Sandro Dentella *:-)
http://sqlkit.argolinux.org SQLkit home page - PyGTK/python/sqlalchemy
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