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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)
466
With the Django QuerySet class, you can apply filters that return QuerySets defined by your filters. The filter() method returns all objects that match the keyword arguments given to the method.
To answer your specific question, there is no "not equal to" but that's probably because django has both "filter" and "exclude" methods available so you can always just switch the logic round to get the desired result.
This is because a Django QuerySet is a lazy object. It contains all of the information it needs to populate itself from the database, but will not actually do so until the information is needed.
The filter() method is used to filter you search, and allows you to return only the rows that matches the search term.
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.
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