Django Custom Queryset filters

python django django-queryset generator-expression
interstar picture interstar · Mar 23, 2009 · Viewed 12.9k times · Source

Is there, in Django, a standard way to write complex, custom filters for QuerySets?

Just as I can write 

MyClass.objects.all().filter(field=val)

I'd like to do something like this :

MyClass.objects.all().filter(customFilter)

I could use a generator expression 

(x for x in MyClass.objects.all() if customFilter(x))

but that would lose the chainability and whatever other functions the QuerySets provide.

Answer

Carl Meyer picture Carl Meyer · Mar 23, 2009

The recommendation to start using manager methods is a good one, but to answer your question more directly: yes, use Q objects. For example:

from django.db.models import Q

complexQuery = Q(name__startswith='Xa') | ~Q(birthdate__year=2000)

MyModel.objects.filter(complexQuery)

Q objects can be combined with | (OR), & (AND), and ~ (NOT).

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