Editing django-rest-framework serializer object before save

Question

I want to edit a django-rest-framwork serializer object before it is saved. This is how I currently do it -

def upload(request):
    if request.method == 'POST':
        form = ImageForm(request.POST, request.FILES)
        if form.is_valid(): # All validation rules pass
             obj = form.save(commit=False)
             obj.user_id = 15
             obj.save()

How can I do it with a django-rest-framework serializer object?

@api_view(['POST','GET'])
def upload_serializers(request):
    if request.method == 'POST':
         serializer = FilesSerializer(data=request.DATA, files=request.FILES)
         if serializer.is_valid():
              serializer.save()

Answer 1

Now edited for REST framework 3

With REST framework 3 the pattern is now:

if serializer.is_valid():
    serializer.save(user_id=15)

Note that the serializers do not now ever expose an unsaved object instance as serializer.object , however you can inspect the raw validated data as serializer.validated_data .

If you're using the generic views and you want to modify the save behavior you can use the perform_create and/or perform_update hooks...

def perform_create(self, serializer):
    serializer.save(user_id=15)

Answer 2

You can edit the serializer's object before save the serializer:

if serializer.is_valid():
    serializer.object.user_id = 15 # <----- this line
    serializer.save()

Answer 3

Just in case you need to modify the data before validation, there is another option without needing to override the functions create or perform_create . Just use the to_internal_value function on your serializers class:

class MySerializer(serializers.ModelSerializer):
    class Meta:
        model = MyModel
    def to_internal_value(self, data):
        data['field1'] = "new value for field 1"
        data['field2'] = "new value for field 2"
        data['field3'] = "new value for field 3"
        return super().to_internal_value(data)

So we can modify the data before doing the validation.