Serializers vs views to retrieve object by foreign key field - django

Question

I'd like to allow users to perform POST request to create a blog post, and to use the topic name instead of the topic id as an option.
A minimal model might look as follows.
models.py
class Topic(models.Model):
name = models.CharField(max_length=30, unique=True)
description = models.CharField(max_length=100)
class Post(models.Model):
name = models.CharField(max_length=30)
topic = models.ForeignKey(Topic, on_delete=models.PROTECT)
created_on = models.DateTimeField(blank=True, auto_now_add=True, editable=False)
Now there are 2 possible approaches that I've considered:
1) Keep the views simple.
views.py
class PostList(ListCreateAPIView):
queryset = Post.objects.all()
serializer_class = PostSerializer
serializers.py
class PostSerializer(serializers.ModelSerializer):
topic_name = serializers.CharField()
class Meta:
model = Topic
fields = ('name', 'topic_name', 'created_on')
read_only_fields = ('created_on',)
def validate_topic_name(self, value):
"""Verify that the topic exists."""
if not Topic.objects.filter(name=value).exists():
raise serializers.ValidationError("Specified Topic Name does not exist!")
else:
return value
def create(self, validated_data):
"""Create a Post."""
topic_name = validated_data.pop('topic_name', None)
topic = Topic.objects.get(name=topic_name)
return Post.objects.create(topic=topic, **validated_data)
2) Keep the serializers simple.
views.py
class PostList(ListCreateAPIView):
queryset = Post.objects.all()
def create(self, request, *args, **kwargs):
serializer = self.get_serializer(data=request.data)
if not serializer.is_valid():
return Response(
serializer.errors, status=status.HTTP_400_BAD_REQUEST)
topic = get_object_or_404(Topic, name=serializer.data['topic_name'])
post = Post.objects.create(
name=serializer.data['name'],
topic=topic)
return Response({'name': serializer.data['name'], 'description': serializer.data['topic_name']},
status=status.HTTP_201_CREATED)
serializers.py
class PostSerializer(serializers.ModelSerializer):
topic_name = serializers.CharField()
class Meta:
model = Topic
fields = ('name', 'topic_name', 'created_on')
read_only_fields = ('created_on',)
My question are:
Where should I put the complexity? In the serializer on in the views?
Is there a better way to proceed?

Answer 1

There's no need to put this complexity into your code at all, because this function is already provided by serializers.SlugRelatedField, which allows you to refer to a related field using a string instead of an id. Here's how it looks with your model:
views.py
class PostList(ListCreateAPIView):
queryset = Post.objects.all()
serializer_class = PostSerializer
serializers.py
class PostSerializer(serializers.ModelSerializer):
topic = serializers.SlugRelatedField(slug_field='name',
queryset=Topic.objects.all())
class Meta:
model = Post
fields = '__all__'