DJango REST Framework Read Only field - django

Question

I have a field owner that is a ForeignKey to User model.
This field is required at the time of creation. But it can not be changed later on.
How to make fields Non-Editable? Is there any other way than creating multiple serializers?
Garage Model
class GarageDetails(models.Model):
owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.PROTECT, )
name = models.CharField(_('Garage Name'), max_length=254, blank=False, null=False, unique=True)
price = models.IntegerField(_('Price'), blank=False)
available_from = models.TimeField(_('Available From'), default=datetime.time(6, 00), blank=False)
available_till = models.TimeField(_('Available till'), default=datetime.time(18, 00), blank=False)
description = models.TextField(_('Garage Description'), blank=True, null=True)
create_date = cmodels.UnixTimestampField(_('Date Added'), auto_now_add=True)
update_date = cmodels.UnixTimestampField(_('Date Added'), auto_created=True)
is_available = models.BooleanField(_('Available'), default=True)
Serializer
class UserFKSerializer(serializers.ModelSerializer):
class Meta:
model = get_user_model()
fields = ('id', 'name', 'email', 'mobile')
class GarageSerializer(serializers.ModelSerializer):
owner = UserFKSerializer(many=False, read_only=True)
class Meta:
model = GarageDetails
fields = '__all__'
read_only_fields = ('id', 'owner', 'create_date', 'update_date')
Views
class GarageRegister(generics.ListCreateAPIView):
renderer_classes = (JSONRenderer, )
permission_classes = (IsAuthenticated, )
#csrf_exempt
def post(self, request, *args, **kwargs):
serialize = GarageSerializer(data=request.data)
if serialize.is_valid():
# Create Garage with owner & name
class GarageUpdate(generics.ListCreateAPIView):
renderer_classes = (JSONRenderer, )
permission_classes = (IsAuthenticated, )
#csrf_exempt
def post(self, request, *args, **kwargs):
serialize = GarageSerializer(data=request.data)
if serialize.is_valid():
# Update Garage but can't update create_date, id, owner & name

Answer 1

You could create a different model serializer for each use case (update, create):
specifying that field in read_only_fields in your model serializer:
class MyModelSerializer(serializers.ModelSerializer):
class Meta:
model = MyModel
fields = ('a', 'nother', 'field')
read_only_fields = ('owner',)
for django forms instead you set the disabled field:
class MyModelForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
form.fields['owner'].widget.attrs['disabled'] = True

Answer 2

You can do this by overriding the "update" method as follows:
def update(self, instance, validated_data):
if 'owner' in validated_data:
del validated_data['owner']
return super().update(instance, validated_data)
This will silently ignore the owner field on updates. If you want to you may instead "raise ValidationError('owner may not be set on updates')" but if you do so you may want to read the model instance and only raise the error if it's actually a change to avoid false positives.
Also, if you're using the python2, the "super" call needs to be "super(GarageSerializer, self)" or some such.