django rest framework nested objects get or create behaviour - django

Question

I am creating an api end point using django-rest-framework for a specific json input. I have two related models like so (let's assume post can only have one category):
class Category(models.Model):
name = models.CharField(max_length=10)
slug = models.SlugField()
class Post(models.Model):
category = models.ForeignKey()
title = models.CharField(max_length=100)
text = models.CharField(max_length=256)
and my serializer are simple model serializers:
class CategorySerializer(ModelSerializer):
id = serializers.IntegerField(required=True)
class Meta:
model = Category
class PostSerializer(ModelSerializer):
id = serializers.IntegerField(required=True)
category = CategorySerializer()
class Meta:
model = Post
and my api view is very simple also:
class PostAPIView(mixins.CreateModelMixin, GenericAPIView):
serializer_class = PostSerializer
permission_classes = (IsAuthenticated,)
now in order to create posts I need to parse a json input like this:
{
"id": 10,
"pk": 10
"title": "Some title",
"text": "Some text",
"category": {
"id": 15,
"pk": 15
"name": "Best category",
"slug": "best-category"
}
}
in here 'pk' parameters are crucial for me, I want data to be created on my db using exact pk provided in json. Now if I make a post request and there are no posts with id:10 and categories with id:15 all is fine and data is written to db new records get inserted, but if there are any when rest-framework returns an error like ['Post id 10 already exists'], I would like matching records to be updated according to input instead. How can I do that?

Answer 1

You just need to add the UpdateMixin, just import it like the CreateModelMixin.
This mixin will implement the update and partial update methods, that will do what you want.
But you can not send a POST, for it you will need a PUT, or PATCH. You you want to do this on POST, I recommend you to implement your own create view method.