How to create and restore a backup from SqlAlchemy?

I'm writing a Pylons app, and am trying to create a simple backup system where every table is serialized and tarred up into a single file for an administrator to download, and use to restore the app should something bad happen.

I can serialize my table data just fine using the SqlAlchemy serializer, and I can deserialize it fine as well, but I can't figure out how to commit those changes back to the database.

In order to serialize my data I am doing this:

from myproject.model.meta import Session
from sqlalchemy.ext.serializer import loads, dumps
q = Session.query(MyTable)
serialized_data = dumps(q.all())

In order to test things out, I go ahead and truncation MyTable, and then attempt to restore using serialized_data:

from myproject.model import meta
restore_q = loads(serialized_data, meta.metadata, Session)

This doesn't seem to do anything... I've tried calling a Session.commit after the fact,开发者_开发技巧 individually walking through all the objects in restore_q and adding them, but nothing seems to work.

What am I missing? Or is there a better way to do what I'm aiming for? I don't want to shell out and directly touch the database, since SqlAlchemy supports different database engines.

You have to use Session.merge() method instead of Session.add() to put deserialized object back into the session.