It's not happening everytime.
And I am not using mysql-python, instead, I use pymysql.
So, the root cause is connection in bad state?
How to fix or work around from sqlalchemy side?
Wesley
在 2014年3月27日星期四UTC+8下午8时58分40秒，Michael Bayer写道：
>
> when the DBAPI cursor has no .description object, it is determined to not
> be a result-row returning object. The MySQLDB DBAPI has been observed to
> occasionally have issues in this area, when a connection gets into a bad
> state. There are likely patterns in how you’re calling it that lead it to
> have this issue but you might try a different DBAPI like
> mysql-connector-python just to see what’s different.
>
>
>
>
> On Mar 27, 2014, at 7:41 AM, Ni Wesley <nis...@gmail.com <javascript:>>
> wrote:
>
> Hi all,
> Today I get an error as title.
> I use sqlalchemy + mysql.
> Here is my code snippet:
>
> def dbquery(_table,whereclause):
>
> try:
>
> #_table=Table(tablename, metadata, autoload=True)
>
> #_table = tables[tablename]
>
> i=_table.select().where(whereclause)
>
> if direct_engine: #direct_engine is True
>
> res = engine.execute(i)
>
> return res
>
> else:
>
> session = scoped_session(sessionmaker(bind=engine))
>
> res = session.execute(i)
>
> return res
>
> session.close()
>
> except Exception,e:
>
> #dba_logger.log(40,'Exception when dbwriter:%s' % str(e))
>
> #dba_logger.log(20,'Exception detail:%s' % str(kwargs))
>
> exctrace('db','1','Error happened when querying
> db',dba_logger,'Exception when dbquery:%s' % str(e),'Exception detail:%s' %
> str(whereclause))
>
> #session.rollback()
>
> if not direct_engine:
>
> session.close()
>
> Here is snippet in another file involving dbquery:
>
> try:
>
> res = dbquery(tables[*'sessions_details'*],whereclause=and_(tables[
> *'sessions_details'*].c.app_key==*self*.app_key,tables[
> *'sessions_details'*].c.device_token==*self*._devicetoken))
>
> except Exception,e:
>
> exctrace(*'db'*,*'1'*,*'Error happened when querying
> db'*,dba_logger,*'Exception
> when query session_details:%s'* % str(e),*'Exception detail:appkey is
> %s,devicetoken is %s'* % (*self*.app_key,*self*._devicetoken))
>
> *self*.read_message()
>
> return
>
> if res is None:
>
> logger.log(40,*'When query connection,mysql has gone or something,
> just skip db and go-on'*)
>
> #here need to justify 0 or 1, later on
>
> *self*.status=*'0'*
>
> *self*.read_message()
>
> return
>
> if res.first() is None:
>
> if json_obj[*'action'*] == *'reg'*:
>
> So, the line in pink above raises the exception.
>
> Could anyone give some suggestion how this happened?
>
>
> Thanks.
>
> Wesley
>
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