Django Creating a Custom User with the Django Rest

I'm trying to create a custom user using the Django Rest Framework. I got it to the point to where I can create a regular user, but I'm unsure on how to extend it to the custom user model.

models.py:

from django.db import models
from django.contrib.postgres.fields import ArrayField
from django.contrib.auth.models import User


class UserProfile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    languages = ArrayField(models.CharField(max_length=30, blank=True))

serializers.py:

from rest_framework import serializers
from django.contrib.auth.models import User


class UserSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True)

    class Meta:
        model = User
        fields = ('first_name', 'last_name', 'email', 'username', 'password')

    def create(self, validated_data, instance=None):
        user = super(UserSerializer, self).create(validated_data)
        user.set_password(validated_data['password'])
        user.save()
        return user

views.py:

@api_view(['POST'])
@permission_classes((AllowAny,))
def create_user(request):
    serialized = UserSerializer(data=request.data)
    if serialized.is_valid():
        serialized.save()
        return Response(serialized.data, status=status.HTTP_201_CREATED)
    else:
        return Response(serialized._errors, status=status.HTTP_400_BAD_REQUEST)

How do I extend the languages field to the UserSerializer to where it can process it? Would it be better to create a signal for every time a user is created it then creates a userprofile automatically?

You can do it two ways, either by creating a profile Serializer or without it. With Serializer,

class UserProfileSerializer(serializers.ModelSerializer):
    languages = serializers.ListField(child=serializers.CharField(max_length=30, allow_blank=True))

    class Meta:
        model = UserProfile
        fields = ('languages',)

class UserSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True)
    userprofile = UserProfileSerializer(required=False)

    class Meta:
        model = User
        fields = ('first_name', 'last_name', 'email', 'username', 'password', 'userprofile')


    def create(self, validated_data, instance=None):
        profile_data = validated_data.pop('userprofile')
        user = User.objects.create(**validated_data)
        user.set_password(validated_data['password'])
        user.save()
        UserProfile.objects.update_or_create(user=user,**profile_data)
        return user

without a profile serializer

class UserSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True)
    languages = serializers.ListField(child=serializers.CharField(max_length=30, allow_blank=True), source="userprofile.languages")

    class Meta:
        model = User
        fields = ('first_name', 'last_name', 'email', 'username', 'password', 'lanugages')


    def create(self, validated_data, instance=None):
        profile_data = validated_data.pop('userprofile')
        user = User.objects.create(**validated_data)
        user.set_password(validated_data['password'])
        user.save()
        UserProfile.objects.update_or_create(user=user,**profile_data)
        return user