Calling Model Method Via Django Rest Framework View

Question

I have a model:

class Size(models.Model):
    size = models.DecimalField(max_digits=5, decimal_places=1)

    def plus_one(self):
        self.size += 1
        self.save()

And I have a simple serializer for this:

class SizeSerializer(serializers.ModelSerializer):
    class Meta:
        model = Size
        fields = '__all__'

How can I call a plus_one model method from my view, using DRF? How is it callable, what is good practice for that? Thanks!

Added:

class SizeAPIView(generics.UpdateAPIView):
    serializer_class = SizeSerializer
    queryset = Size.objects.filter()

Can you show your view?

neverwalkaloner
– neverwalkaloner

2018-06-23 14:31:43 +00:00
Commented Jun 23, 2018 at 14:31 — neverwalkaloner
– neverwalkaloner, Commented Jun 23, 2018 at 14:31
@neverwalkaloner made, but this is just abstaract

D. Make
– D. Make

2018-06-23 14:37:48 +00:00
Commented Jun 23, 2018 at 14:37 — D. Make
– D. Make, Commented Jun 23, 2018 at 14:37

neverwalkaloner · Accepted Answer · 2018-06-23 14:43:48Z

3

If I understood you right you need to call plus_one each time when object updated. In this case you can override perform_update() method like this:

class SizeAPIView(generics.UpdateAPIView):
    serializer_class = SizeSerializer
    queryset = Size.objects.filter()

    def perform_update(self, serializer):
        serializer.save()
        serializer.instance.plus_one()

answered Jun 23, 2018 at 14:43

neverwalkaloner

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3 Comments

D. Make Over a year ago

What is about best practice? Is it good, when i create adittional ready_for_plus bool field in Model and add if ready_for_plus = True to plus_one method? Idea is to give access to method from API request. Anyway thank, you make it clear, again:).

neverwalkaloner Over a year ago

@D.Make you are welcome. Not sure but probably it would be better to override model's save() method. In this case you will not required doubled save operation.

D. Make Over a year ago

got it, so i will do, tnx!

mrehan · Accepted Answer · 2018-06-23 19:19:09Z

2

This should be done on serializer level while your SizeAPIView remains unchanged:

class SizeSerializer(serializers.ModelSerializer):
    class Meta:
        model = Size
        fields = '__all__'

    def update(self, instance, validated_data):

        for attr, value in validated_data.items():
            setattr(instance, attr, value)

        instance.plus_one()  # performs `instance.save` too.

Documentation on saving instances.

answered Jun 23, 2018 at 19:19

mrehan

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