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()

Your first paragraph seems incomplete. “This how I do it with” what? — Donal Fellows, Nov 26 '12 at 11:00

Tom Christie · Answer 1 · 2015-01-19T17:31:27.600

78

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)

edited Jan 19 '15 at 17:31

answered Nov 26 '12 at 12:05

Tom Christie

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2

It looks like this has changed to `perform_create()` in DRF 3.x. – nnyby Jan 16 '15 at 15:49
1

Hint: inside the `perform_create()` method, you can access `self.request`, `self.args`, and `self.kwargs`. – Karim Sonbol Sep 03 '16 at 13:17
1

This can not be used when we need conditional modification. – Iqbal Jun 21 '18 at 19:46

score 34 · Accepted Answer · edited Sep 16 '13 at 21:27

34

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

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

edited Sep 16 '13 at 21:27

paulmelnikow

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answered Feb 28 '13 at 21:35

zephyr

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Can one modify a nested object ? serializer.object.book.author_id = 22 – Amogh Talpallikar Jan 28 '15 at 19:50
12

`serializer.validated_data['user_id'] = 15` works on 3.8.2 – Iqbal Jun 21 '18 at 19:45
11

Serializer object has no attribute 'object'. – Alex78191 Dec 08 '19 at 19:43

score 0 · Answer 3 · answered Sep 29 '22 at 09:02

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.

Editing django-rest-framework serializer object before save

3 Answers3

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