Django REST attribute error

Question

I am trying to write serializers for my models that are inherited from some base classes, but I get an attribute error. I would appreciate any help.

Base class:

class AbstractTranslationModel(models.Model): class Meta: abstract = True language = models.CharField(max_length=2, choices=LANGUAGES) # Translatable fields name = models.CharField(max_length=22) description = models.TextField(default='') def __str__(self): return self.name + ' ' + str(self.language) 

Subclass:

 class SkillTranslation(AbstractTranslationModel): class Meta: unique_together = (('translation_of', 'language'), ) # Foreign keys translation_of = models.ForeignKey(Skill, related_name='translations', related_query_name='translation') 

Here is the serializer for this class:

 class SkillTrSerializer(serializers.ModelSerializer): class Meta: model = SkillTranslation fields = ('language', 'name', 'description', ) 

And here is the serializer for the class, which contains the following:

 class SkillSerializer(serializers.ModelSerializer): translations = SkillTrSerializer() class Meta: model = Skill fields = ('translations', ) 

Here is the console output:

 >>> from skills.models import * >>> from api.serializers import * >>> skill = Skill.objects.all().first() >>> skill.translations.all() [<SkillTranslation: English skill EN>, <SkillTranslation:  RU>] >>> skill.translations.all().first() <SkillTranslation: English skill EN> >>> skill.translations.all().first().language 'EN' >>> s = SkillSerializer(instance=skill) >>> s.data AttributeError: Got AttributeError when attempting to get a value for field `language` on serializer `SkillTrSerializer`. The serializer field might be named incorrectly and not match any attribute or key on the `RelatedManager` instance. Original exception text was: 'RelatedManager' object has no attribute 'language'. 

EDIT: Here is more information.

 >>> s SkillSerializer(instance=<Skill: English skill>): translations = SkillTrSerializer(): id = IntegerField(label='ID', read_only=True) language = ChoiceField(choices=(('EN', 'English'), ('RU', 'Russian'), ('UA', 'Ukrainian')), required=True) name = CharField(max_length=22) description = CharField(required=False, style={'base_template': 'textarea.html'}) translation_of = PrimaryKeyRelatedField(queryset=Skill.objects.all(), required=True) 

Thanks Anton

Answer 1

translations is the inverse of the Skill model, so Skill.transations is a one-to-many relationship. In your serializer, you defined it as a one-to-one relationship, so DRF cannot find any of the attributes because they do not exist on the QuerySet . To fix this, you just need to use many=True :

 class SkillSerializer(serializers.ModelSerializer): translations = SkillTrSerializer(many=True)