Django Rest Framework associating Related Model with current User

Question

I'll start by explaining the current scenario of my problem.

Models

There are 5 models for example: Community, User, Membership, Reservation, Item

class User(Model):
    name = CharField(max_length=50)
    communities = ManyToManyField('Community', through='Membership')


class Community(Model):
    name = CharField(max_length=50)


class Membership(Model):
    user = ForeignKey('User')
    community = ForeignKey('Community')


class Item(Model):
    name = CharField(max_length=50)


class Reservation(Model):
    item = ForeignKey('Item')
    membership = ForeignKey('Membership')

• Community is m:m User through Membership.
• Reservation is 1:m Membership
• Item is 1:m Reservation

ModelSerializer

class ReservationSerializer(ModelSerializer):
    class Meta:
        model = Reservation
        fields = ('membership', 'item')

Problem

What's the best approach to automatically set the User value from request.user, hence the attribute that is required for this ReservationSerializer is just the community and item instead of membership and item?

References

• How to create a django User using DRF's ModelSerializer
• Return the current user with Django Rest Framework
• http://www.django-rest-framework.org/tutorial/4-authentication-and-permissions#associating-snippets-with-users
• Django Rest Framework ModelSerializer Set attribute on create
• Dynamically limiting queryset of related field
• djangorestframework: Filtering in a related field

Answer 1

The role of the serializer is to represent the information in a legible way, not to manipulate such data. You may want to do that on a view: Using the generic ListCreateAPIView available on DRF, you could use the pre_save signal to store that information:

from rest_framework.generics import ListCreateAPIView

class ReservationView(ListCreateAPIView):
    def pre_save(self, obj):
        obj.membership.user = self.request.user