Django: Filter a Queryset made of unions not working

Question

I defined 3 models related with M2M relationsships

class Suite(models.Model):
    name = models.CharField(max_length=250)
    title = models.CharField(max_length=250)
    icon = models.CharField(max_length=250)

    def __str__(self):
        return self.title



class Role(models.Model):
    name = models.CharField(max_length=250)
    title = models.CharField(max_length=250)
    suites = models.ManyToManyField(Suite)
    services = models.ManyToManyField(Service)
    Actions = models.ManyToManyField(Action)
    users = models.ManyToManyField(User)

    def __str__(self):
        return self.title

In one of my views I tried to collect all the Suites related to an specific User. The user may be related to several Roles that can contain many Suites. And then filter Suites by name. But the filter seem to have no effects

queryset = Suite.objects.union(*(role.suites.all() for role in 
self.get_user().role_set.all()))
repr(self.queryset)

'<QuerySet [<Suite: energia>, <Suite: waste 4 thing>]>'

self.queryset = self.queryset.filter(name="energia")
repr(self.queryset)

'<QuerySet [<Suite: energia>, <Suite: waste 4 thing>]>'

The query atribute inside the queryset not alter its content before executin the filter:

(SELECT "navbar_suite"."id", "navbar_suite"."name", "navbar_suite"."title", "navbar_suite"."icon" FROM "navbar_suite") UNION (SELECT "navbar_suite"."id", "navbar_suite"."name", "navbar_suite"."title", "navbar_suite"."icon" FROM "navbar_suite" INNER JOIN "navbar_role_suites" ON ("navbar_suite"."id" = "navbar_role_suites"."suite_id") WHERE "navbar_role_suites"."role_id" = 1)

(SELECT "navbar_suite"."id", "navbar_suite"."name", "navbar_suite"."title", "navbar_suite"."icon" FROM "navbar_suite") UNION (SELECT "navbar_suite"."id", "navbar_suite"."name", "navbar_suite"."title", "navbar_suite"."icon" FROM "navbar_suite" INNER JOIN "navbar_role_suites" ON ("navbar_suite"."id" = "navbar_role_suites"."suite_id") WHERE "navbar_role_suites"."role_id" = 1)

Answer 1

As stated in django docs, only count(), order_by(), values(), values_list() and slicing of union queryset is allowed. You can't filter on union queryset.

That means, you have to apply filters on queries before applying union on them.

Also, you can achieve your goal without even using union():

Suite.objects.filter(role_set__users=self.get_user(), name="energia")

You may need to adjust field name in filter if you've used related_name or related_query_name in definition of suites M2M field in Role model.