Always True Q object

Based on this answer we can make conditional argument passing

Obj.filter(
    *( (Q(some_f1=some_v1),) if some  else ()),    
    f1=v1,
    f2=v2,
    f3=v3,
    f4=v4,
    ...
)

So, if some is True we add tuple (Q(some_f1=some_v1),) to arguments list, in other case we add empty tuple (), also we need to wrap it in *(), as always when we passing tuple of non-keyword args

Try this;

conditions = {'f1':f1,'f2':f2, 'f3':f3}
if some:
    conditions['some_f1'] = some_v1

Obj.objects.filter(**conditions)

Here's one way to get an always true Q object:

always_true = ~Q(pk__in=[])

The ORM optimizer recognises that Q(pk__in=[]) always evaluates to False, and the ~ negates it to make it True.

as Alasdair answered in comment:

Obj.filter(
    Q(some_f1=some_v1) if some else Q(), 
    f1=v1,
    f2=v2,
    f3=v3,
    f4=v4,
    ...
)