如何修改 django rest 框架发送的响应

Question

I am using Django REST as backend and angular as front end.

I have two serializers one for readong GET requests and other for POST, PUT requests.

This was because there are few fields like interval , etc which i am entering in integer by user but in the database i am saving as timedelta so i have to multitply them to make them as seconds on front end.

so eg interval = 5 entered by user and i am posting 5*60*60 to server.

In order to read i have made ReadSerializer where i am diving that by 60*60 to again show to user what he added.

This is working find my problem is after saving my object to database the djnago rest frameework sends the object as it is saved which has interval = 5*60*60 . inerval is just an example there 4-5 felds where i am changing them in front end before posting

Is there any way that response used my READ serializer before sending

class Serializer(serializers.ModelSerializer):
    interval = serializers.SerializerMethodField('get_interval')

    class Meta:
        model = User
        fields = ('id', 'interval')

    def get_interval(self, obj):
        return obj.interval/60*60

class WriteSerializer(serializers.ModelSerializer):

    class Meta:
        model = User
        fields = ('id', 'interval')

This is the view

class UserListCreateView(generics.ListCreateAPIView):
    queryset = User.objects.filter(is_deleted=False)

    def get_serializer_class(self):
        if self.request.method == 'GET':
            return ReadSerializer
        return WriteSerializer

Answer 1

You can use the transform_field method which allows you to customize the representation of a field when showing it.

Documentation about it: http://www.django-rest-framework.org/api-guide/serializers/#customizing-field-representation

Btw, careful if you are planning to upgrade to new versions of drf (>=3), these methods may disappear in favour of a unique to_representation method: https://groups.google.com/forum/?fromgroups#!topic/django-rest-framework/9kp5kXCssR4

Answer 2

I would just change it in JavaScript on the front end. However I have a similar issue and solved it like this, (warning, I just started using DRF, so may not be the best way):

Just change the response of the method directly by first getting the original response, then editing the data property of it, which is a dict (pre-serialized) of the data to return:

class UserListCreateView(generics.ListCreateAPIView):
    ...

    def list(self, request, *args, **kwargs):
            response = super().list(request, *args, **kwargs)
            response.data['interval'] = response.data['interval'] / 60 / 60
            return response