Results.objects.all().select_related('profile','testcase')
that was easy
that's A join B,C
if it was A join B join C
(my example)
class Release
fk Artist
class Artist
fk Label
class Label
Release.objects.all().select_related('artist','artist_label')
note selecting the C class via the B class 'B_C'
On Thu, Feb 5, 2009 at 5:28 PM, Daniel Roseman <
[email protected]> wrote:
>
> On Feb 5, 3:50 pm, rc <[email protected]> wrote:
> > I am newbie to Django and I am struggling to get my arms around DJango
> > and it's data access api (models).
> >
> > I have these models:
> >
> > class Profile(models.Model):
> > profile_id = models.AutoField(primary_key=True)
> > profile_name = models.CharField(max_length=75)
> > def __unicode__(self):
> > return self.profile_id
> > def __unicode__(self):
> > return self.profile_name
> > class Meta:
> > db_table = 'profile'
> >
> > class Testcase(models.Model):
> > test_id = models.AutoField(primary_key=True)
> > test_name = models.CharField(max_length=300)
> > src = models.ForeignKey(Source, null=True, blank=True)
> > bitrate = models.IntegerField(null=True, blank=True)
> > test_type = models.CharField(max_length=300)
> > output_resolution = models.CharField(max_length=15, blank=True)
> > def __unicode__(self):
> > return self.test_name
> > class Meta:
> > db_table = 'testcase'
> >
> > class Results(models.Model):
> > result_id = models.AutoField(primary_key=True)
> > date = models.DateTimeField()
> > test = models.ForeignKey(Testcase)
> > profile = models.ForeignKey(Profile)
> > status = models.CharField(max_length=30)
> > graph = models.BlobField(null=True, blank=True)
> > y_psnr = models.DecimalField(null=True, max_digits=5,
> > decimal_places=2, blank=True)
> > u_psnr = models.DecimalField(null=True, max_digits=5,
> > decimal_places=2, blank=True)
> > v_psnr = models.DecimalField(null=True, max_digits=5,
> > decimal_places=2, blank=True)
> > yuv_psnr = models.DecimalField(null=True, max_digits=5,
> > decimal_places=2, blank=True)
> > def __unicode__(self):
> > return self.result_id
> > class Meta:
> > db_table = 'results'
> >
> > and I want to be able to display this data:
> >
> > select result_id, date, profile_name, test_name, status, y_psnr,
> > u_psnr, v_psnr, yuv_psnr
> > from profile, testcase, results
> > where profile.profile_id = results.profile_id
> > and testcase.test_id = results.test_id
> >
> > Which is very easy to do with raw sql, but struggling to do it the
> > "django' way.
> >
> > Any ideas?
> > I have also tried to use raw sql, but struggled to get it to work in
> > my views and templates.
>
> The Django ORM is there to help you. If you don't find it easy, don't
> use it. However, the simple way of doing it would be something like
> this:
>
> for testcase in Testcase.objects.all():
> print testcase.status
> for result in testcase.result_set.all():
> print result.result_id, result.date,
> result.profile.profile_name, \
> result.status, result.y_psnr, \
> result.u_psnr, result.v_psnr, result.yuv_psnr
>
> You can make that much more efficient via proper use of
> select_related, but that's the general idea.
>
> Not related to your problem, but you've got an issue with your inner
> Meta classes - each time they are indented under the __unicode__
> method. They should be one indent level back.
>
>
> >
>
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