Issue using nested serializer with django-rest-framework

I'm trying to create a nested serializer, UserLoginSerializer , composed of a UserSerializer and a NotificationSerializer, but I'm getting this error when it tries to serialize:

> AttributeError: Got AttributeError when attempting to get a value for
> field email on serializer UserSerializer. The serializer field
> might be named incorrectly and not match any attribute or key on the
> UserSerializer instance. Original exception text was:
> 'UserSerializer' object has no attribute 'email'.

Here is my models.py:

class Notification(models.Model):
    kind = models.IntegerField(default=0)
    message = models.CharField(max_length=256)

class User(AbstractUser):
    username = models.CharField(max_length=150, blank=True, null=True)
    email = models.EmailField(unique=True)
    customer_id = models.UUIDField(default=uuid.uuid4, editable=False)

And my serializers.py:

class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = User
        fields = [
            "id",
            "first_name",
            "last_name",
            "email",
            "customer_id"
        ]

class NotificationSerializer(serializers.ModelSerializer):

    class Meta:
        model = Notification
        fields = [
            "id",
            "kind",
            "message",
        ]

class UserLoginSerializer(serializers.Serializer):
    user_info = UserSerializer(read_only=True)
    notifications = NotificationSerializer(many=True, read_only=True)

The error occurs at the last line in this endpoint:

def get_login_info(self, request):
    notifications = Notification.objects.filter(recipient=request.user)
    serializer = UserLoginSerializer(
        {
            "user_info": UserSerializer(request.user),
            "notifications": NotificationSerializer(notifications, many=True),
        }
    )
    return Response(serializer.data)

What am I doing wrong?

You can use .data attribute.

def get_login_info(self, request):
    notifications = Notification.objects.filter(recipient=request.user)
    serializer = UserLoginSerializer(
        {
            "user_info": UserSerializer(request.user).data,
            "notifications": NotificationSerializer(notifications, many=True).data,
        }
    )
    return Response(serializer.data)

You must pass the data, not the serializer objects themselves. The data argument allows you to pass in a dictionary of data that will be used by the inner serializers to create a serialized representation. In this case, you will pass in the serialized data from the UserSerializer and NotificationSerializer to the UserLoginSerializer, which then returns the final serialized representation of the data.

Or, you may pass user and notifications directly as such:

def get_login_info(self, request):
    notifications = Notification.objects.filter(recipient=request.user)
    serializer = UserLoginSerializer(
        {
            "user_info": request.user,
            "notifications": notifications
        }
    )
    return Response(serializer.data)

Django Rest Framework model serializers have a to_representation method which converts the model instances to their dictionary representation, so in this case, the UserLoginSerializer will automatically use the UserSerializer and NotificationSerializer to serialize the user and notifications data. You can modify/change this method's behaviour by overriding it.

I hope this helps.