Sorry for duplicate post How to create
Union<http://stackoverflow.com/questions/23110658/how-to-create-union-in-django-queryset>
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
Is there any other way to do this task?
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