How to create a connection in Django

Question

I am using the Django REST Framework in a project and I want to create a union of 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 request

SELECT id,name FROM tbl_a UNION (SELECT b.id,b.name From tbl_b b)

My attempt to unite

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 the original model 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 to make an 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 searched on it, basically answered this problem as using a list for both models. But I do not want to use a list since I am using the Django Rest Framework, so I need a QuerySet. So my question is, if I use a list to combine, can I convert the resulting list to a QuerySet.

Note: I do not want to use SQL Query in Django

Is there any other way to accomplish this task?

Answer 1

Q django . this_link .