django select_for_update and select_related on same query?

Question

Does anyone know if you can do both the .select_for_update() and .select_related() statements in a single query? Such as:

employee = get_object_or_404(Employ         


        

Answer 1

You can't use select_related with foreign keys that are nullable when you are using select_for_update on the same queryset.

This will work in all cases:

Book.objects.select_related().select_for_update().get(name='Doors of perception')

Answer 2

Since Django 2.0, you can use select_for_update together with select_related even on nullable relations - by using new parameter of=...

Using their Person example from docs, you could do

Person.objects.select_related('hometown').select_for_update(of=('self',))

which would lock only the Person object