Django ORM: When, Case, F (keyword: zero division error)

django_orm_when_case_f_example.py

from django.db.models import F, Case, When, FloatField
from myapp import models

md = models.MyModel.objects.filter(pk=3).annotate(pr=Case(When(price__gte=40., then=F('price') * 10), default=F('price') / 10, output_fields=FloatField())).first()

In [27]: md.price
Out[27]: 40.7424047560126

In [29]: md.pr
Out[29]: 407.424047560126

md = models.MyModel.objects.filter(pk=3).annotate(pr=Case(When(price__lte=30., then=F('price') * 10), default=F('price') / 10, output_fields=FloatField())).first()

In [32]: md.pr
Out[32]: 4.07424047560126