Thanks guys
The problem in this case with querying against ItemRatingsByGroup is that
not all Items are in there.
Only the items that have been rated are in items rated by group
I'm looking to display as following:
The Group
All the items in the group
A rating for each item - if a rating exists
So I need to go about it by getting all the items for the group at some
point
On 4/15/07, Michael Trier <[EMAIL PROTECTED]> wrote:
>
>
> You need to query against your ItemRatingsByGroup table directly where
> the group_id equals the group you want. That will give you all the
> info you want, the item, the group, and the rating.
>
> Michael
>
> On 4/15/07, Paul Rauch <[EMAIL PROTECTED]> wrote:
> >
> > tejas schrieb:
> > > Hi - I'm a Django newbie and I have a query that, using the syntax in
> > > the database API, would become very slow. I'm wondering what the way
> > > around it is.
> > >
> > > I have 3 tables
> > >
> > > Group -- contains a list of groups
> > >
> > >
> > > Item: (each item belongs to a group)
> > > ForeignKey(groupid)
> > >
> > > ItemRatingsByGroup: (the rating for each item from each group)
> > > ForeignKey(groupid)
> > > ForeignKey(itemid)
> > > rating
> > >
> > > So in the ItemRatingsByGroup Table there at most one row for each
> > > (item, group) combo (some groups may not have rated an item)
> > >
> > > I want to list the items in a group - and also show the rating given
> > > by that group. Using SQL this would be a left join from Item to
> > > ItemRatingsByGroup
> > >
> > >
> > > But using the Django ORM (not using exact syntax)
> > >
> > > items = Item.objects.get(groupid=desiredgroupid)
> > >
> > > for item in items:
> > > ratings =
> > > item.item_ratings_by_group_set.filter(groupid=desiredgroupid)
> > > #there's only 0 or 1 results
> > > for rating in ratings:
> > > #display the rating with the item
> > >
> > >
> > > In the Django ORM case, a new query would seem to be executed to get
> > > the ratings for each item.
> > >
> > > Is there anything in Django to help me execute this query (I don't
> > > think select_related works backwards). Also on a related note, how do
> > > I find out what queries Django is running?
> > >
> > > thanks
> > >
> > >
> >
> >
> http://www.djangoproject.com/documentation/faq/#how-can-i-see-the-raw-sql-queries-django-is-running
> >
> > here you can see what queries django is running.
> >
> > mfg Paul Rauch
> >
> > >
> >
>
>
> --
> Michael Trier
> http://www.railsconsulting.com
>
> >
>
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