python - Overide serializer.data in Django REST Framework -

i've been trying alter value of form field django rest framework's admin panel , reason change never takes place. have serializer below

class someview(modelviewset):   queryset = mymodel.objects.all()   serializer_class = mymodelserializer    # want override , change post data   def perform_create(self, serializer):      user = self.request.user.id       # form field manually entered user id      # want default logged in user      serializer.data['user'] = user       # returns original user entered form field      print serializer.data 

i checked out serializer.data dir() , it's python dictionary can't figure out why can't modify value. test tried add values doesn't work either

# doesnt work serializer.data['some_new_field'] = 'test' 

edit

on note, can copy data , edit it

fake_data = serializer.data.copy() fake_data['old_value'] = 'new value' 

however fails validate

serializer = mymodelserializer(data=fake_data) serializer.is_valid() # returns false 

edit edit:

ok, validation error caused django returning simplelazyobject. works when perform copy on data, i'm curious why can't edit serializer.data directly without copying it. problem solved now, if can provide insight on issue curiosity, awesome.

i checked out serializer.data dir() , it's python dictionary can't figure out why can't modify value.

while value return serializer.data indeed dictionary, serializer.data not simple instance variable.

if @ rest_framework/serializers.py:

class serializer(baseserializer):     # [...]     @property     def data(self):         ret = super(serializer, self).data         return returndict(ret, serializer=self) 

returndict inherits ordereddict, still new dictionary every time access serializer.data.

the real data in _data, noted underscore might not want modify either not intended public. values filled serializer.to_representation() override on viewset.

as second part: modelviewset defines get_serializer() called request post data create serializer want modify. i'd suggest try change input data before serializer created, instead.