Django Rest Framework filtering calculated model property

Question

Sorry for a newbie question. I have a following model:

class WeightSlip(models.Model):

    grossdate = models.DateTimeField(auto_now=False, auto_now_add=False)
         


        

Answer 1

Extending the answer further. With the latest django and drf version one might experience an exception like this.

Exception

File "/home/USER/.env/drf3/lib64/python3.7/site-packages/django/db/models/query.py", line 76, in iter setattr(obj, attr_name, row[col_pos]) AttributeError: can't set attribute

Versions Used: Django==3.1 djangorestframework==3.11.1 django-filter==2.3.0

The solution that worked for me is this where slipdate and netweight requires model name to be used in the queryset...

def filter_slipdate(self, queryset, name, value):
    if value:
       queryset = queryset.annotate(WeightSlip__slipdate=Case(When(grossdate__gt=F('taredate'), then=F('grossdate')), default=F('taredate'))).filter(WeightSlip__slipdate=value)
    return queryset

def filter_netweight(self, queryset, name, value):
    if value:
        queryset = queryset.annotate(WeightSlip__netweight=F('grossweight') - F('tareweight')).filter(WeightSlip__netweight=value)
    return queryset
    return queryset