How to update modified_by field with CurrentUserDefualt - django

Question

i get this error when i am trying to update modified_by field
Tried to update field sales.CustomersTag.modified_by with a model instance, <SimpleLazyObject: <UserProfile: Admin>>. Use a value compatible with CharField.
this is my serializer.py:
class CustomersTagSerializer(serializers.ModelSerializer):
created_by = serializers.CharField(read_only=True, default=serializers.CurrentUserDefault())
modified_by = serializers.CharField(read_only=True, default=serializers.CurrentUserDefault())
def update(self, instance, validated_data):
instance.name = validated_data.get('name', instance.name)
instance.modified_by = validated_data.get('modified_by', instance.modified_by)
instance.save()
return instance
class Meta:
model = models.CustomersTag
fields = (
'id',
'name',
'created_date',
'modified_date',
'created_by',
'modified_by',
)
and this my view.py:
class CustomerTagGetIdPutView(generics.RetrieveAPIView,
mixins.UpdateModelMixin):
permission_classes = (AllowAny,)
queryset = models.CustomersTag.objects.all()
serializer_class = CustomersTagSerializer
def get_object(self):
id = self.kwargs['id']
obj = generics.get_object_or_404(models.CustomersTag, id=id)
return obj
def put(self, request, *args, **kwargs):
return self.update(request, *args, **kwargs)
def patch(self, request, *args, **kwargs):
return self.update(request, *args, **kwargs)
i tried alot to solve this problem but i can't .. any one can help me for this problem

Answer 1

If you're using Django REST Framework generic views and no overriding the behavior of methods like get_serializer or get_serializer_context, your serializer will receive a context object. This context object is a dictionary with the request and the view object.
That said, you can do this by overriding create() and update() in your serializer. For example:
class CustomersTagSerializer(serializers.ModelSerializer):
class Meta:
model = models.CustomersTag
fields = (
'id',
'name',
'created_date',
'modified_date',
'created_by',
'modified_by',
)
def create(self, validated_data):
user = self.context['request'].user
return models.CustomersTag.objects.create(
created_by=user, **validated_data)
def update(self, instance, validated_data):
user = self.context['request'].user
instance.name = validated_data.get('name', instance.name)
instance.modified_by = user
instance.save()
return instance
But maybe if you want to maintain a log history of editions in your models you could use a package like django-auditlog.

Answer 2

You can do this while calling save() in your model.
For example:
class CustomersTagSerializer(serializers.ModelSerializer):
created_by = models.ForeignKey(User, null=True, editable=False)
modified_by = models.ForeignKey(User, null=True, editable=False)
def save(self, *args, **kwargs):
user = get_current_user()
if user and user.is_authenticated():
self.modified_by = user
if not self.id:
self.created_by = user
super(CustomersTagSerializer, self).save(*args, **kwargs)