True but joins are expensive.
If I only need many2many in one directions I use the list:reference
and I cache the query that maps the id into the representation of the
corresponding record.
Massimo
On Aug 12, 11:10 am, Thadeus Burgess <thade...@thadeusb.com> wrote:
> ew
>
> jaywalking should never be a replacement for joins...
>
> --
> Thadeus
>
> On Thu, Aug 12, 2010 at 2:42 AM, mdipierro <mdipie...@cs.depaul.edu> wrote:
> > Yes, if you use any validator IS_IN_SET or IS_IN_DB with
> > multiple=True
>
> > I think it is still very convenient and can simplify some of your
> > code. Yet on RDBS you can do joins and this should be used a
> > replacement for that.
>
> > On Aug 11, 9:51 pm, Jason Brower <encomp...@gmail.com> wrote:
> >> Should i worry about this on my setups with sqlite but i do not use gae?
> >> Almost all my setups are sqlite but on apachi fcgi.
> >> Best regards,
> >> jason
>
> >> ----- Original message -----
> >> > There was a problem with this which is now fixed.
> >> > This is a very important feature if you plan to develop locally
> >> > (sqlite) and deploy on GAE.
>
> >> > Massimo
>
> >> > On Aug 10, 4:18 am, mdipierro <mdipie...@cs.depaul.edu> wrote:
> >> > > Experimentally there is a new feature in trunk.
>
> >> > > Field('name','list:string')
> >> > > Field('name','list:integer')
> >> > > Field('name','list:reference other table')
>
> >> > > and new operators
>
> >> > > db.mytable.myfield.contains(4)
>
> >> > > which works for list:reference, list:integer, list:string, string and
> >> > > text types.
>
> >> > > The list: type are mapped differently on RDBS ([1,2,3]->'|1|2|3|') and
> >> > > on GAE (uses a string list propery). It is backward compatible with
> >> > > data stored using the IS_IN_DB(...,multiple=True). So here is an
> >> > > example of a program:
>
> >> > > # model
> >> > > db.define_table('product',Field('name'),format='%(name)s')
> >> > > db.define_table('purchase',Field('code'),Field('products','list:reference
> >> > > product'))
>
> >> > > # controller
> >> > > def products():
> >> > > db.product.id.represent=lambda id: A('click
> >> > > me',_href=URL('purchases_by_product',args=id))
> >> > > return
> >> > > dict(form=crud.create(db.product),items=db(db.product.id>0).select())
> >> > > def purchases():
> >> > > return
> >> > > dict(form=crud.create(db.purchase),items=db(db.purchase.id>0).select())
> >> > > def purchases_by_product():
> >> > > product_id=request.args(0)
> >> > > return
> >> > > dict(items=db(db.purchase.products.contains(product_id)).select())
>
> >> > > Now register some products. When you try register purchases you should
> >> > > automatically get a SELECT window with product names. The list of
> >> > > items should also show a comma separated list of product names.
>
> >> > > I have not tested this on GAE. I could use some tests. Please let me
> >> > > know.
>
> >> > > Massimo
