lol... i have answered to late ...
it seems that after all i have said the same thing as Tiago
Regards
On Mon, Sep 14, 2009 at 11:58 PM, Alexandru-Emil Lupu
<gang.al...@gmail.com>wrote:
> i do not know if is database killing or not, but you could try some of
> those
>
> Person.objects.select_related(depth=2).get()
>
>
> or you could make something like
>
> Membership.objects.select_related(depth=1).get()
>
> That will perform a query on the entire membership table and related tables
> in order to extract the values
> but you could try something like
>
> Membership.objects.distinct('person_id').select_related(depth=1).get()
>
>
> Alecs
>
>
>
>
> On Mon, Sep 14, 2009 at 11:27 PM, W.P. McNeill <bill...@gmail.com> wrote:
>
>>
>> Never mind. Tiago Serafim's reply answered my question for me.
>>
>> Follow on question: say I want to make a 2-dimensional table of the
>> dates when people joined bands. I'd have code that looks like this.
>>
>> for p in Person.objects.all():
>> for g in Group.objects.all():
>> date = Membership.objects.get(person=p, group=g).join_date
>> ...
>>
>> Am I making (person x group) database calls here? This is impression
>> I get from reading:
>>
>> http://docs.djangoproject.com/en/dev/ref/models/querysets/#id1
>>
>> Is this inefficient? Is there a way to do this with a single database
>> call?
>>
>>
>> On Sep 14, 11:43 am, "W.P. McNeill" <bill...@gmail.com> wrote:
>> > Or maybe another way of asking this, since I don't want to force you
>> > to write Python code just to answer my question...
>> >
>> > If I have the music group model written as shown in the Django
>> > documentation is it possible to write a model API statement that gets
>> > me this information, or would I have to add fields to the model?
>> >
>> > Thanks.
>> >
>> > On Sep 14, 9:46 am, Alexandru-Emil Lupu <gang.al...@gmail.com> wrote:
>> >
>> >
>> >
>> > > basically you would have to make a ManyToMany relation thru a class.
>> In that
>> > > class you make m,n,date field
>> > > After that you just use a query to answer the question: Who (Paul)?
>> joined
>> > > to whom (Beatles), and after that will pop up the ManyToMany date
>> field that
>> > > will answer to question "when".
>> >
>> > > I am preety new in django my self .. and i don't know pretty well how
>> to do
>> > > it...
>> >
>> > > On Mon, Sep 14, 2009 at 6:21 PM, W.P. McNeill <bill...@gmail.com>
>> wrote:
>> >
>> > > > I can't figure out how to query the values of fields in a ManyToMany
>> > > > "through" table.
>> >
>> > > > For instance, say I'm working with the Beatles database in the
>> Django
>> > > > documentation (
>> http://docs.djangoproject.com/en/dev/topics/db/models/
>> > > > #extra-fields-on-many-to-many-relationships<
>> http://docs.djangoproject.com/en/dev/topics/db/models/%0A#extra-field..
>> .>).
>> > > > I want to be able to
>> > > > query the date on which Paul joined the Beatles. (As opposed to
>> when
>> > > > Ringo joined the Beatles, or when Paul joined Wings.) Basically I
>> > > > want to treat the Group table as a two-dimensional array, look up:
>> >
>> > > > Group[Beatles][Paul].date_joined
>> >
>> > > > and have it return:
>> >
>> > > > date(1960, 8, 1)
>> >
>> > > > I'd think this would be easy to do, but I've been playing around
>> with
>> > > > the command-line database API and I can't figure it out. The
>> > > > documentation I've seen describes how to use a Membership field as a
>> > > > filter criteria, but not how to look up the actual value.
>> >
>> > > --
>> > > As programmers create bigger & better idiot proof programs, so the
>> universe
>> > > creates bigger & better idiots!
>> > > I am on web: http://www.alecslupu.ro/
>> > > I am on twitter:http://twitter.com/alecslupu
>> > > I am on linkedIn:http://www.linkedin.com/in/alecslupu
>> > > Tel: (+4)0748.543.798
>> >>
>>
>
>
> --
> As programmers create bigger & better idiot proof programs, so the universe
> creates bigger & better idiots!
> I am on web: http://www.alecslupu.ro/
> I am on twitter: http://twitter.com/alecslupu
> I am on linkedIn: http://www.linkedin.com/in/alecslupu
> Tel: (+4)0748.543.798
>
>
--
As programmers create bigger & better idiot proof programs, so the universe
creates bigger & better idiots!
I am on web: http://www.alecslupu.ro/
I am on twitter: http://twitter.com/alecslupu
I am on linkedIn: http://www.linkedin.com/in/alecslupu
Tel: (+4)0748.543.798
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