On 2014-11-29 16:19, Michael Bayer wrote:
>>> opList = dbSession.query(PendingOperation).filter_by(opcode=opcode).all()
>
> looks easy enough to reproduce:
>
> import codecs
>
> x = u'\u0142'
>
> codecs.utf_8_decode(x)
>
> that is, in Py2K when you call decode() on a unicode object already, things
> go wrong.
>
> SQLAlchemy shouldn’t be attempting to run this decode operation unless the
> MySQL driver used here is acting in a flaky way, that is, SQLAlchemy did a
> test on first connect to see if a Unicode() type comes back as u’’ or not.
> That it’s trying to do the decode means that it didn’t, yet then on this
> column it is.
>
> The MySQL driver in use here would be of top importance in determining why
> this might be happening, I guess this is the “gaerdbms” driver?
Exactly! The connection string looks like this:
> 'mysql+gaerdbms:///{}?instance={}'.format(...)
when running on Google App Engine, and like this:
> 'mysql://{}:{}@{}/{}'.format(...)
when running in a local setting.
The DB session is created like this (upon connecting, we set SQL mode to
traditional):
> from sqlalchemy import create_engine, event
> from sqlalchemy.orm import sessionmaker
>
> def makeEngine():
> connectionString = ...
>
> eng = create_engine(connectionString,
> case_sensitive=True,
> encoding='utf-8',
> isolation_level='REPEATABLE READ'
> )
>
> @event.listens_for(eng, "first_connect", insert=True) # make sure we're
> the very first thing
> @event.listens_for(eng, "connect")
> def receive_connect(dbapi_connection, connection_record):
> sqlMode = 'TRADITIONAL'
> cursor = dbapi_connection.cursor()
> cursor.execute("SET sql_mode = '{0}'".format(sqlMode))
>
> return eng
>
> engine = makeEngine()
> Session = sessionmaker(
> bind=engine,
> autoflush=True,
> autocommit=False
> )
> So the best approach for MySQL is to ensure that the driver is predictable
> about unicode include, specify use_unicode=0 in the URL (see
> http://docs.sqlalchemy.org/en/rel_0_9/dialects/mysql.html#unicode).
Like this? :
'mysql+gaerdbms:///{}?instance={}&charset=utf8&use_unicode=0'.format(...)
'mysql://{}:{}@{}/{}&charset=utf8&use_unicode=0'.format(...)
Why is gaerdbms flaky?
I understand this is a bug in the driver?
I don't think we have meddled with anything here, like MySQL's default
character encoding or something like that.
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