code: def create(self, validated_data):
          
          if 'user' not in validated_data:
              validated_data['user'] = self.context['request'].user
          return super(RefreshTokenSerializer, self).create(validated_data)
docs: Override ``create`` to provide a user via request.user by default.
  
          This is required since the read_only ``user`` field is not included by
          default anymore since
          https://github.com/encode/django-rest-framework/pull/5886.