CODEWITHSUNDEEP
djangofilteringdjango-queryset
Agos
Agos

Reputation: 19450

Django excluding specific instances from queryset without using field lookup

I sometimes have the need to make sure some instances are excluded from a queryset.
This is the way I do it usually: 

unwanted_instance = MyModel.objects.get(pk=bad_luck_number)
uninteresting_stuff_happens()
my_results = MyModel.objects.exclude(id=unwanted_instance.id)

or, if I have more of them:

my_results = MyModel.objects.exclude(id_in=[uw_in1.id, uw_in2.id, uw_in3.id])

This 'feels' a bit clunky, so I tried:

my_ideally_obtained_results = MyModel.objects.exclude(unwanted_instance)

Which doesn't work. But I read here on SO that a subquery can be used as parameter for exclude.
Am I out of luck? Am I missing some functionality (checked the docs, but didn't find any useful pointer)

Upvotes: 58

Views: 56851

Answers (3)

Seyyid Said
Seyyid Said

Reputation: 525

You can put your unwanted items in a list , and a fetch all items except those in the list like so:

MyModel.objects.exclude(id__in=[id1,id2,id3 ])

Upvotes: 2

kartheek
kartheek

Reputation: 6704

The Given answer is perfect and try this which works fine for me

step 1)

 from django.db.models import Q

step 2)

 MyModel.objects.filter(~Q(id__in=[o.id for o in <unwanted objects>]))

Upvotes: 8

obeattie
obeattie

Reputation: 3354

The way you're already doing it is the best way.

If it's a model-agnostic way of doing this you're looking for, don't forget that you can do query.exclude(pk=instance.pk).

Just as an aside, if Django's ORM had an identity mapper (which it doesn't at present), then you would be able to do something like MyModel.objects.filter(<query>).all().remove(<instance>), but you're out of luck in that regard. The way you're doing it (or the one above) is the best you've got.

Oh, and also you can do much better than that in query with a list comprehension: query.exclude(id__in=[o.id for o in <unwanted objects>])

Upvotes: 99

Related Questions