web.py + pony orm?

[Tomas Schertel]

Is some one using this combination?

[Aydın ŞEN]

someone use web.py + sqlalchemy rom

2013/4/19 Tomas Schertel <tsch...@gmail.com>

Is some one using this combination?

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Aydın Şen

[Leandro Severino]

Hello Tomas,

    What's the advantage of the use of the pony instead db module of web.py ?

[Tomas Schertel]

Adige,

You'll find web.py + sqlalchemy in web.py's cookbook.

[Tomas Schertel]

Hi Leandro.

I can't say what's the real advantage. I'm just curious.

[Alexander Kozlovsky]

Hi, Pony ORM developer here. We just get first public attention today, so I don't think there are many
experienced Pony ORM users exist at this moment (April 2013) ;-)

I think that currently Pony ORM is suitable for experiments, but probably not for immediate in-production usage.
Currently Pony ORM is a great toy, and during the next few months we must implement several tasks in order

to get complete product. For example, we must add support of Psycopg2 PostgreSQL driver (currently we work
with PostgreSQL via PyGreSQL which is not as popular as Psycopg2). This is not hard, but just takes some time.
Also, we must add migration support (and its implementation will be really cool, we plan to get migrations
automatically from diagram changes in visual diagram editor).

I expect Pony ORM will be fully production-ready a few months later.

Regarding to benefits of using Pony ORM, I think its mainly in higher level of abstraction. With Pony, you can
write query to database as if you write simple python generator to iterate over ordinary python list of objects.
So, you can do something like this

    orders = select(o for o in Order if o.date_shipped.year == 2012)

And you get optimized SQL query which return list of order objects. You can pass this objects between
several layers of you application, and when some of this objects are updated, Pony ORM accumulates
these updates and then send changes to database on commit() execution.

The main architectural difference between Pony ORM and SQLAlchemy is this: SQLAlchemy based
on relational data model, and can write queries to relational databases only, whereas Pony ORM
internally based on "entity-relationship" model which is independent of SQL. So, in the future, Pony ORM
could be used with NoSQL databases such as MongoDB. But currently only SQL databases are supported.

So, at the current time the main difference between Pony ORM and SALAlchemy is that SQLAlchemy
queries are more verbose. For example, this is Pony ORM query:

    select(o for o in Order if o.date_shipped.year == 2012)

And this is equivalent SQLAlchemy query (did't test it):

    session.query(Order).filter(extract("year", Order.date_shipped) == 2012)

This is really the matter of taste and personal preferences, so no critique here.
SQLAlchemy is great ORM, but I just forget correct query syntax every time :)
I hear from many people that they cannot handle SQLAlchemy "complexity",
so maybe Pony ORM will be good choice for them.

[Aydın ŞEN]

Tomas,

I mean i am using web.py + sqlalchemy :)

2013/4/20 Alexander Kozlovsky <alexander...@gmail.com>

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Aydın Şen

[Tomas Schertel]

Thanks for your feedback Alexander.

I really hope Pony gets ready for production soon.