gistfile1.txt

class F(Combinable):
    def __init__(self, name):
        self.name = name
        self.functions = []

    def __getattr__(self, name):
        def wrapper(*args, **kwargs):
            self.functions.append((name, args, kwargs))
            return self
        return wrapper


Book.objects.filter(F('data').key('owner').key('name') == 'Brad')
Book.objects.filter(F('data').key('owner').key('name').eq('Brad'))
Book.objects.filter(F('data').key('owner').key('birthday').cast(DateField).year() < 1980)
Book.objects.filter(F('data').key('owner').key('birthday').cast(DateField).year().lt(1980))

# Allow transforms in order_by:

https://code.djangoproject.com/ticket/24747

# Allow Func Expressions to be used as Transforms:

https://code.djangoproject.com/ticket/24629

Marc's as_transform() PR
https://github.com/django/django/pull/4748

Josh's PR
https://github.com/django/django/pull/4482

Book.objects.filter(F('data').key('owner').key('birthday').cast(DateField).year() < 1980)?

Yup

F('data')['owner']['birthday'].cast(DateField).year() < 1980

And the example from yesterday:

book = M(Book)
Book.objects.filter(
    book.data['owner']['birthday'].cast(DateField).year() < 1980,
    book.title.lower().startswith('a'))