conn has not method rollback(), but db_session does.
conn has not method rollback(), but db_session does.

critzo/piecewise,critzo/piecewise,critzo/piecewise,opentechinstitute/piecewise,opentechinstitute/piecewise,opentechinstitute/piecewise,opentechinstitute/piecewise,critzo/piecewise