I don't want use SQL query in django On Thursday, 17 April 2014 04:39:09 UTC+5, Russell Keith-Magee wrote: > > On Wed, Apr 16, 2014 at 9:30 PM, Shoaib Ijaz > <[email protected]<javascript:>> > wrote: > > Sorry for duplicate post How to create Union > > > > I am using Django REST Framework in project and I want to create union > two > > different Models. > > > > My Models > > > > class A(models.Model): > > name = models.CharField(max_length=240, blank=True) > > geometry = models.GeometryField(blank=True, null=True) > > abwrapper= models.ForeignKey(ABWrapper) > > > > class Meta: > > db_table = 'tbl_a' > > > > class B(models.Model): > > name = models.CharField(max_length=240, blank=True) > > link = models.IntegerField(blank=True, null=True) > > geometry = models.GeometryField(blank=True, null=True) > > abwrapper= models.ForeignKey(ABWrapper) > > > > class Meta: > > db_table = 'tbl_b' > > > > I am trying to create this query > > > > SELECT id,name FROM tbl_a UNION (SELECT b.id,b.name From tbl_b b) > > > > My attempt for union > > > > a = A.objects.values_list('id') > > b = B.objects.values_list('id') > > queryset = a | b > > > > Error: > > AssertionError: Cannot combine queries on two different base models. > > > > Now i tried with parent Model in this way > > > > class ABWrapper(models.Model): > > objects = models.GeoManager() > > class Meta: > > db_table = u'ab_wrapper' > > > > Added this model as ForeignKey above both Models > > > > a = ABWrapper.objects.filter(a__isnull=False).values('a__id') > > b = ABWrapper.objects.filter(b__isnull=False).values('b__id') > > queryset = a | b > > > > Error: > > TypeError: Merging 'GeoValuesQuerySet' classes must involve the same > values > > in each case. > > > > Another attempt by making alias > > > > a = > > > ABWrapper.objects.filter(a__isnull=False).extra(select={'tempID':'a__id'}).values_list('tempID') > > > > b = > > > ABWrapper.objects.filter(b__isnull=False).extra(select={'tempID':'b__id'}).values_list('tempID') > > > > queryset = a | b > > > > Error: > > ValueError: When merging querysets using 'or', you cannot have > > extra(select=...) on both sides. > > > > I have searched on it, mostly answered this issue as using list for both > > models. But I don't want to use list as I am using Django Rest Framework > so > > I need QuerySet. So my question if I use list for union can I convert > > resulting list into QuerySet. > > > > Note: I don't want to use SQL Query in Django > > Why not? That would seem to be the exact answer you need. > > You appear to have a very specific idea of the SQL query you want to > issue, including UNION clauses (an operator that Django's ORM doesn't > support) and "extra" columns (which means the data you want is outside > your regular Django model). Getting this query in 100% native Django > query sets is going to be somewhere between difficult and impossible. > > However, you don't have to drop right back to SQL cursors - Django has > raw query sets for exactly this purpose: > > ABWrapper.objects.raw("SELECT …. FROM … WHERE") > > This will return ABWrapper objects contained in a query set object > that should be compatible with Django REST Framework, but you get > those objects by providing the exact SQL you want to execute. > > See: > > https://docs.djangoproject.com/en/dev/topics/db/sql/ > > for more details > > Yours, > Russ Magee %-) >
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