How to set current user to user field in Django Rest Framework?

Question

I have the following code working perfectly. I can create a Post object from DRF panel by selecting an image and a user. However I want DRF to populate the user

Answer 1

Try this:

def post(self, request, format=None)

        serializer = ProjectSerializer(data=request.data)
        request.data['user'] = request.user.id


        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)

        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST

Answer 2

This is what works for me in serializers.py, where I am also using nested data. I want to display created_by_username without having to lookup other users.

class ListSerializer(serializers.ModelSerializer):
    """
    A list may be created with items
    """
    items = ItemSerializer(many=True)

    # automatically set created_by_id as the current user's id
    created_by_id = serializers.PrimaryKeyRelatedField(
        read_only=True,
    )

    created_by_username = serializers.PrimaryKeyRelatedField(
        read_only=True
    )


    class Meta:
        model = List
        fields = ('id', 'name', 'description', 'is_public',
            'slug', 'created_by_id', 'created_by_username', 'created_at',
            'modified_by', 'modified_at', 'items')

    def create(self, validated_data):
        items_data = validated_data.pop('items', None)
        validated_data['created_by_id'] = self.context['request'].user
        validated_data['created_by_username'] = self.context['request'].user.username
        newlist = List.objects.create(**validated_data)

        for item_data in items_data:
            Item.objects.create(list=newlist, **item_data)
        return newlist

Answer 3

You will have to override the default behavior of how generics.ListCreateAPIView creates an object.

class PhotoListAPIView(generics.ListCreateAPIView):
    queryset = Post.objects.filter(hidden=False)
    authentication_classes = (SessionAuthentication, BasicAuthentication)
    permission_classes = (IsAuthenticated,)

    def get_serializer_class(self):
        if self.request.method == 'POST':
            return CreatePostSerializer
        else:
            return ListPostSerializer

    def create(self, request, *args, **kwargs):
        # Copy parsed content from HTTP request
        data = request.data.copy()

        # Add id of currently logged user
        data['user'] = request.user.id

        # Default behavior but pass our modified data instead
        serializer = self.get_serializer(data=data)
        serializer.is_valid(raise_exception=True)
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

The .get_serializer_class() is not necessary as you can specify which fields are read-only from your serializer, but based on the projects I have worked on, I usually end up with 'asymmetric' serializers, i.e. different serializers depending on the intended operation.

Answer 4

It depends on your use case. If you want it to be "write-only", meaning DRF automatically populates the field on write and doesn't return the User on read, the most straight-forward implementation according to the docs would be with a HiddenField:

class PhotoListAPIView(generics.ListCreateAPIView):
    user = serializers.HiddenField(
        default=serializers.CurrentUserDefault(),
    )

If you want want it to be readable, you could use a PrimaryKeyRelatedField while being careful that your serializer pre-populates the field on write - otherwise a user could set the user field pointing to some other random User.

class PhotoListAPIView(generics.ListCreateAPIView):
    user = serializers.PrimaryKeyRelatedField(
        # set it to read_only as we're handling the writing part ourselves
        read_only=True,
    )

    def perform_create(self, serializer):
        serializer.save(user=self.request.user)

Finally, note that if you're using the more verbose APIView instead of generics.ListCreateAPIView, you have to overwrite create instead of perform_create like so:

class PhotoListAPIView(generics.ListCreateAPIView):
    user = serializers.PrimaryKeyRelatedField(
        read_only=True,
    )

    def create(self, validated_data):
        # add the current User to the validated_data dict and call
        # the super method which basically only creates a model
        # instance with that data
        validated_data['user'] = self.request.user
        return super(PhotoListAPIView, self).create(validated_data)

Answer 5

You can use CurrentUserDefault:

user = serializers.PrimaryKeyRelatedField(
    read_only=True, 
    default=serializers.CurrentUserDefault()
)

Answer 6

Off the top of my head, you can just override the perform_create() method:

class PhotoListAPIView(generics.ListCreateAPIView):
    ...
    def perform_create(self, serializer):
        serializer.save(user=self.request.user)

Give that a shot and let me know if it works