[odb-users] Crash on accessing odb::result object.

[Tolga HOŞGÖR]

You cannot operate on result (iterating in this code) after ending the
transaction.

On Fri, Jul 17, 2015 at 1:40 AM Mike O'Driscoll <
modriscoll at clearpathrobotics.com> wrote:

> Hello Users,
>
> I'm in the process of evaluating the ODB libraries using Postgresql and
> encountering the following crash after getting results from a query.
>
> If I only instantiate "r" and don't provide it a query result everything
> works fine.
> Although if I call "db_->query" and act upon the results, I get a segfault
> on empty or trying to work with the iterator.
>
> I've tried to follow the examples as closely as possible but continue to be
> unable to progress.
> Any thoughts or insights would be appriciated.
>
> GDB backtrace:
>
> Program received signal SIGSEGV, Segmentation fault.
>
> #0  0x00007ffff416a4a0 in odb::pgsql::select_statement::next() ()
> >    from /usr/lib/x86_64-linux-gnu/libodb-pgsql-2.4.so
> > #1  0x00007ffff6bb9edc in
> > odb::pgsql::object_result_impl<mytype::orm::Task>::next (this=0x65cb10)
> at
> > /usr/include/odb/pgsql/simple-object-result.txx:102
> > #2  0x00007ffff6bb291a in begin (this=0x65cb10)
> >     at /usr/include/odb/simple-object-result.hxx:76
> > #3  empty (this=0x7fffffffc720) at /usr/include/odb/result.hxx:200
> > #4  mytype::orm::MyORM::getUncompletedTasks (this=0x64f610)
> >     at /path/to/my_orm.cpp:107
>
>
>
> Code:
>
>   odb::core::transaction t(db_->begin());
> >   odb::core::query<mytype::orm::Task> q_rt;
> >   q_rt = odb::core::query<mytype::orm::Task>(
> >     odb::core::query<mytype::orm::Task>::task_state
> > != mytype::orm::COMPLETED);
> >   ROS_INFO("ORM: Querying for uncompleted tasks");
> >   // Transact the database and query it.
> >   odb::core::result<mytype::orm::Taskt> r =
> >           db_->query<mytype::orm::Task>(q_rt);
> >   t.commit();
> >   ROS_INFO("ORM: Processing results, count: %d", r.size());
> >   // Take all results and push them to a results vector
> >   if (!r.empty())
> >   {
> >     for (odb::result<mytype::orm::Taskt>::iterator i = r.begin();
> >          i != r.end();
> >          ++i)
> >     {
> >       ROS_INFO("ORM: Processing Loop");
> >       // non_complete_tasks.push_back(i->task());
> >     }
> >   }
> >   ROS_INFO("ORM: Found %d, uncompleted tasks",
> non_complete_tasks.size());
>
>
>
> --
> Mike O'Driscoll
>