CODEWITHSUNDEEP
django
user1518217
user1518217

Reputation: 614

Django filter queryset based on many to many extra fields model

Here is a models example.

class Person(models.Model):
      name = models.CharField(max_length=128)

      def __unicode__(self):
          return self.name

class Group(models.Model):
      name = models.CharField(max_length=128)

      def __unicode__(self):
          return self.name

class Membership(models.Model):
      person = models.ForeignKey(Person)
      group = models.ForeignKey(Group)

I want to get all Person objects, and for each one adding a column 'is_member' that values True if the person is member at least of one group.

I try with annotate and count, but I'm a bit confused... Thank you.

Upvotes: 1

Views: 136

Answers (2)

Paulo Pessoa
Paulo Pessoa

Reputation: 2569

Try this :

Person.objects.annotate(
    is_member=Case(
        When(membership=True, then=True), default=False, output_field=BooleanField()
        )
    ).distinct('id')

if you want learn more about this, conditional-expressions can help u.

Upvotes: 1

ettanany
ettanany

Reputation: 19806

The following should work for you:

persons = []
for p in Person.objects.all():
    if p.membership_set.all():
        p.is_member = True
    else:
        p.is_member = False
    persons.append(p)

Upvotes: 0

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