On Aug 25, 2009, at 2:08 PM, Mike Orr wrote:
> Can you give an example of this? I've read about the features but I
> don't quite have my head around them. Are you talking about mappers
> that leave some columns unmapped, or queries that return calculated
> results alongside ORM objects, etc?
Let's say you have articles that map to authors. You set it all up
using mapper with relations, each article has an author, and each blog
might have multiple authors related. You eventually need to do more
low-level SQL type queries. So say instead of doing:
stories =
Session
.query(Article).join(Article.blog).filter(Blog.name=='Tech').all()
You then realize, well, you don't really need the ORM, its slowing you
down, you just want all the id's and titles. Instead of using the
whole SQL table query stuff, in SA 0.5 you can do:
stories = Session.query(Article.id,
Article.title).join(Article.blog).filter(Blog.name=='Tech').all()
So we can just select multiple attributes, and the rest of the lingo
stays the same. We're still utilizing the 'blog' back-ref property on
the Article that we setup with the SA ORM level mapper stuff. Of
course, instead of Article objects back, we get an AttributeTuple list
of rows just like when you do a lower level SA SQL query. It's verrrry
slick.
Of course, as with the lower level of SA, you have the same
limitations, these are just row-tuple's now with 2 attributes, no lazy
loading of relations, etc. Which is fine for me as I want my speed and
specific attributes. You can even combine them, like so:
stories = Session.query(Article, Blog.id).join(Article.blog)....
for article, blog_id in stories:
etc....
And yes, Article will be the fully SA ORM mapped object.
It's also waaay shorter than doing the query with all the table
objects and such. :)
Cheers,
Ben
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"pylons-discuss" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/pylons-discuss?hl=en
-~----------~----~----~----~------~----~------~--~---
