CODEWITHSUNDEEP
djangodjango-rest-frameworkdjango-serializer
Winters
Winters

Reputation: 1089

Django REST Framework SerializerMethodField vs Django model methods

When creating a serializer in Django REST Framework, I understand that I can create a SerializerMethodField that creates a new read-only method for a model. For example:

class AnswerSerializer(serializers.ModelSerializer):
    likes_count = serializers.SerializerMethodField()

    class Meta:
        model = Answer
        exclude = ["a_field"]

    def get_likes_count(self,instance):
        return instance.voters.count()

A similar thing could also be done using a property or method in the models.py file:

class Answer(models.Model):

    @property
    def get_likes_count(self):
        return voters.count()

So my question is:

What are the pros and cons of each? I understand that SerializerMethodField is for read_only operations but aside from that are not sure.

Is it best practice to keep the models.py file for model fields only, and to use signals for update/create operations and serializers for read operations?

Upvotes: 0

Views: 709

Answers (1)

Iain Shelvington
Iain Shelvington

Reputation: 32244

One advantage to using the serializer approach instead of the @property approach is that you can use annotations on the queryset passed to the serializer

 AnswerSerializer(Answer.objects.annotate(likes_count=Count('voters')), many=True)

def get_likes_count(self, instance):
    return getattr(instance, 'likes_count', None) or instance.voters.count()

This way you can use annotations to reduce the number of queries you make and have a fall back that calculates the value anyway

Upvotes: 2

Related Questions