Drf: Update or create a model instance - django

Question

i have an attendance model that has a unique together constraint for date and user fk field, right now my implimentation of the createorupdate is an if else that doesn't look nice
def create(self, validated_data):
user = validated_data.get('user', None)
date = validated_data.get('date', None)
if date is not None:
user = Attendance.objects.filter(user=user, date=date).first()
if user is not None:
instance = Attendance.objects.update(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance
else:
instance = Attendance.objects.create(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance
this works the only issue is that the returned object from the update is null for all the fields and i need a better implimentation example
the full serializer:
class AttendanceSerializer(serializers.ModelSerializer):
date = serializers.HiddenField(default=timezone.now)
leave_reason = serializers.CharField(required=False, default="")
class Meta:
model = Attendance
fields = ['user', 'presence', 'leave_reason', 'date'] #all the fields except pk
extra_kwargs = {
'user': {'required': True},
'presence': {'required': True},
'leave_reason': {'required': False},
}
# validators = [
# UniqueForYearValidator(
# queryset=Attendance.objects.all(),
# field='user',
# date_field='date',
# message=("You have already taken the attendance")
# )
# ]
def create(self, validated_data):
user = validated_data.get('user', None)
date = validated_data.get('date', None)
if date is not None:
user = Attendance.objects.filter(user=user, date=date).first()
if user is not None:
instance = Attendance.objects.update(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance
else:
instance = Attendance.objects.create(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance

Answer 1

I'm only familiar with the .update() after Attendace.objects.filter() and not after Attendance.objects. Maybe try this:
def create(self, validated_data):
user = validated_data.get('user', None)
date = validated_data.get('date', None)
if date is not None:
user_var = Attendance.objects.filter(user=user, date=date).first()
if user is not None:
instance = user_var.update(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance
else:
instance = Attendance.objects.create(
user=validated_data['user'],
presence=validated_data['presence'],
leave_reason=validated_data['leave_reason'],
date=validated_data['date'],
)
return instance