Django DRF: POST to CreateAPIView with list of PrimaryKeyRelatedFields - django

Question

I have a many-to-one relationship between the following models
class Story(models.Model):
id = models.CharField(max_length=12, primary_key=True)
class Article(models.Model):
id = models.CharField(max_length=16, primary_key=True)
title = models.CharField(max_length=500)
address = models.URLField()
story = models.ForeignKey(to=Story, blank=True, null=True, on_delete=models.CASCADE)
Suppose I post several article objects to the database successfully.
I identify that the articles with the ids
['1', '2', '3']
are all reporting on a particular Story.
I want create a Story via a POST method to a CreateAPIView view like this
POST http://127.0.0.1/news/story {articles': ['1', '2', '3']}
Here is my serializer
class StorySerializer(serializers.ModelSerializer):
id = serializers.ReadOnlyField()
articles = serializers.PrimaryKeyRelatedField(many=True, allow_empty=False, queryset=Article.objects.all())
class Meta:
model = Story
fields = ('id', 'articles')
Here is my view
class StoryList(generics.ListCreateAPIView):
serializer_class = StorySerializer
queryset = Story.objects.all()
I want to ensure that 1) the articles exist. 2) the article story is updated before the Story object is created.
Suppose I run this as it is, I will get the following error:
Got a TypeError when calling Story.objects.create(). This may be
because you have a writable field on the serializer class that is not
a valid argument to Story.objects.create(). You may need to make the
field read-only, or override the StorySerializer.create() method to
handle this correctly.
So here is an attempt to override the create() method:
def create(self, validated_data):
story_id = None
for article_id in validated_data['articles']:
article = Article.objects.get(id=article_id)
story_id = article.story_id
if story_id:
break
story = Story.objects.get(id=story_id) if story_id else Story.objects.create()
for article_id in validated_data['articles']:
article = Article.objects.get(id=article_id)
article.story_id = story.id
article.save()
story.save()
return story
def update(self, instance, validated_data):
return self.create(validated_data)
The idea here is make sure there are no overlapping stories by merging them.
When I try POST to this view, I encounter a DoesNotExist thrown by the line Article.objects.get(id=article_id)
My questions are
1) Minor : Why am I getting this error
2) Major : Is there a cleaner / correct way of addressing such a use case in django?
Thank you

Answer 1

class StoryList(generics.ListCreateAPIView):
serializer_class = StorySerializer
query_set = Story.objects.all()
It's should be quertset not query_set.
1) Minor : Why am I getting this error
You gived an illegal article_id which is not exist.
2) Major : Is there a cleaner / correct way of addressing such a use case in django?
drf-writable-nested can handle nested write in drf well.