Hi Koonal, As said in django doc <https://docs.djangoproject.com/en/1.10/ref/models/querysets/#order-by> you can use `distinct()` to remove duplicated rows from first query.
I believe with this your pagination should works as expected. Regards, On Thu, Aug 18, 2016 at 2:58 AM, Koonal Bharadwaj <kbharad...@heartflow.com> wrote: > Hello, > > The issue: > > When trying to order_by on a related model duplicate entries are created. > I solved this with an OrderedSet that is applied after paginating ( > http://code.activestate.com/recipes/576694/). However, when I try to > paginate the queryset, all the results are not returned. It's missing a few > table rows. > > Models: > > class HeartFlowCase(models.Model): > """ > > A Hearflow Case. > > This serves at the true state of a case as it is processed through the > system. > It also holds the results of each step of the processing. > > """ > > # Primary > hf_id = models.CharField('HeartFlow ID', max_length=200, blank=True, > unique=True) > canonical_data = models.ForeignKey('cases.CaseData', to_field='uuid', > related_name="canonical_data") > > > class CaseData(models.Model): > """ > Extracted and computed values related to a single processing run of a > case. > > A HeartFlowCase can have multiple runs associated with it. > The one which is accepted to be the "clinically accurate" one is the one > referred to as 'canonical_data' by > the HeartFlowCase itself. > > """ > > # Primary > heartflowcase = models.ForeignKey(HeartFlowCase, related_name='data', > blank=True, null=True) > uuid = models.CharField('Case Data UUID', max_length=200, blank=False, > null=False, unique=True) > deadline = models.DateTimeField('Deadline', blank=True, > default=get_default_deadline) > > > As you can see, there is a ForeignKey to canonical CaseData from > HeartFlowCase and a ForeignKey to HeartFlowCase from CaseData. So you can > have multiple CaseDatas per HeartFlowCase. > > Structure: > > HeartFlowCase > | > data - CaseData1 > \ > \ CaseData2 > > > For example: > > Total number of HeartFlow objects are 5 with 2 CaseDatas each. If I > order_by deadline on CaseData as: > cases = HeartFlowCase.objects.all().order_by(data__deadline) > this returns duplicates since there are multiple CaseDatas, which is fine. > Now I try and paginate it by applying: > > paginator = Paginator(cases, 2) > cases = paginator.page(1) > > Now the SQL query has a LIMIT and OFFSET given. If the order_by gives > duplicate HeartFlowCase objects this hits the LIMIT number and the results > that are returned are missing a HeartFlowCase object. So if 2 duplicates are > returned per case after applying the OrderedSet I get only one case back and > missing one case since it was never returned from the database. As I goto the > next page: > > cases = paginator.page(2) > > that missingHeartFlowCase object that was not returned from the first page > queryset is lost forever and is never displayed. > > > I hope this is clear. Please let me know if I can clarify further. Any help > would greatly be appreciated. Thanks. > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/django-users/61ec03f6-3325-49fe-bcdc-a7ca50784dc0%40googlegroups.com > <https://groups.google.com/d/msgid/django-users/61ec03f6-3325-49fe-bcdc-a7ca50784dc0%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAK52boUF2mNVaU-06TWebfH5JonHvFmdqW103Q_CF1WmWShjJw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
