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 <[email protected]> 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 [email protected]. > To post to this group, send email to [email protected]. > 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 [email protected]. To post to this group, send email to [email protected]. 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.
