This is insane. I chose a case I was confident would work and I still
have the same problem. Check it out:
def save(self, project, **data):
pid = int(project.id)
engine = sqlalchemy.create_engine(cns)
print engine, '...................'
session = sqlalchemy.create_session(bind_to=engine)
print session, '....................'
project = session.query(Project).get(pid)
print project.title, '...................................'
session.flush()
print project.title, '...................................'
session.refresh(project)
print project.title, '...................................'
tg.flash("Changes saved!")
raise tg.redirect("/")
Look at the output now:
<sqlalchemy.engine.threadlocal.TLEngine object at 0xb71d8f2c>
...................
<sqlalchemy.orm.session.Session object at 0xb71d8cac> ....................
Test Project 2 ...................................
Title ...................................
Test Project 2 ...................................
Again, I can't help that this is in a threadlocal context, but it makes
no sense to me why the changes are not saved to the database. The last
line should read:
Title ..............................
Randall
Randall Smith wrote:
> Michael,
>
> Thanks for the advice. I'm working with TurboGears and determined to
> use SA, but having a tough time. TG defines a "PackageEngine" which is
> a subclass of AutoConnectEngine. The SA imports look like this:
>
> import sqlalchemy.mods.threadlocal
> import sqlalchemy
> from sqlalchemy.ext.proxy import AutoConnectEngine
>
> My classes are not bound to a PackageEngine as illustrated in TG
> examples. Instead, I import my classes, which use DynamicMetaData, and
> add them to a session as needed. I define and engine so that it is
> initialized with TG. I then reference that engine when I need a session
> like
>
> from tgwater import model
> session = create_session(bind_to=model.engine)
>
> so that I always reference the same engine. I'm guessing the sessions
> are being opened in separate threads from model.engine. This is not
> working out and I'm sure the answer lies in your response below, but I
> can't seem to put it all together. Here are some symptoms.
>
> Symptom 1.
>
> I receive a persistent (I think) object and want to assign data to it.
> I get the session and work on it like:
> def save(self, project, **data):
> session = sqlalchemy.object_mapper(project).get_session()
> project.title = data['title']
> session.flush()
> But nothing is written to the database and I get no errors.
>
> Symptom 2.
>
> I query an object and pass it from the controller to the template.
> Within the template, the lazy fields are None when they should contain
> values. If I access them first in the controller, the values are there.
> Strange, b/c I would think this is all happening in the same thread.
>
> I don't mean to make this a TG thing. I'm hoping the symptoms will make
> it obvious how I am misusing the SA connections. Thanks for the great
> software and your help.
>
> Randall
>
>
> Michael Bayer wrote:
>
>>connections are generally not held onto anywhere; so connection-using
>>operations are usually threadsafe. the only time a connection is
>>held onto somewhere is when you explicitly hold onto a Connection
>>yourself, or a Transaction, or a SessionTransaction. A
>>SessionTransaction occurs during a session.flush() as well, so
>>Sessions are not connection-threadsafe when used with flush(). if
>>you use a thread-local SessionContext, you should be fine in that
>>regard.
>>
>>Also, objects loaded by a Session may have some lazy-loaders present
>>on them which also can initiate connection-using operations, so that
>>is something to be aware of. if you have objects with unexecuted
>>lazy loaders that are going to be shared among threads, you might
>>want to make sure they dont remain within a session that is going to
>>be used for flush() operations.
>
>
>
> Using Tomcat but need to do more? Need to support web services, security?
> Get stuff done quickly with pre-integrated technology to make your job easier
> Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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