SQLAlchemy, a brave new World

SQLAlchemy becomes an essential technology for any python developper interacting with relational databases. As a Django developper, I have sat on my laurels for long, being completely satisfied with the Django ORM. It was time to explore its challenger.

First, before it sounds like I crush my favorite framework : when Django ORM was developped, there was no SQLAlchemy, or almost no good python ORM at all.

Here are some of the things you might want to know first:

In order to explore SQLAlchemy (SA) I created pyfspot (sources are on github): a very small application to manage the database of the F-Spot photo manager. It is not supposed to save lives, but that will at least be:

I discovered a few concrete things:

# get() does not throw exception
tag = session.query(Tag).get(5)
# filter().one() does ...
    tag = session.query(Photo).filter_by(id=1337).one()
except sqlalchemy.orm.exc.NoResultFound:
    # d'oh!
Photo.base_uri.like('%\\%%', escape="\\")
# A tag
tag = session.query(Tag).filter_by(name='foo').one()
# A set of photos
photoset = session.query(Photo).filter(~Photo.base_uri.endswith('/'))
# intersect() won't work
AttributeError: 'InstrumentedList' object has no attribute 'c'
# Use any()

Well, those were my first steps. As expected, it did not feel so well to relearn how to walk. But at least I am now ready to get my bearings in SQLAlchemy's world.

Original post at Makina Corpus

#python, #django, #sqlalchemy - Posted in the Dev category