How do I do an OR filter in a Django query?

You want to make filter dynamic then you have to use Lambda like

from django.db.models import Q

brands = ['ABC','DEF' , 'GHI']

queryset = Product.objects.filter(reduce(lambda x, y: x | y, [Q(brand=item) for item in brands]))

reduce(lambda x, y: x | y, [Q(brand=item) for item in brands]) is equivalent to

Q(brand=brands[0]) | Q(brand=brands[1]) | Q(brand=brands[2]) | .....

There is Q objects that allow to complex lookups. Example:

from django.db.models import Q

Item.objects.filter(Q(creator=owner) | Q(moderated=False))

It is worth to note that it's possible to add Q expressions.

For example:

from django.db.models import Q

query = Q(first_name='mark')
query.add(Q(email='[email protected]'), Q.OR)
query.add(Q(last_name='doe'), Q.AND)

queryset = User.objects.filter(query)

This ends up with a query like :

(first_name = 'mark' or email = '[email protected]') and last_name = 'doe'

This way there is no need to deal with or operators, reduce's etc.

You can use the | operator to combine querysets directly without needing Q objects:

result = Item.objects.filter(item.creator = owner) | Item.objects.filter(item.moderated = False)

(edit - I was initially unsure if this caused an extra query but @spookylukey pointed out that lazy queryset evaluation takes care of that)