custom serializer for list of custom objects in django example

Here is an example of a custom serializer for a list of custom objects in Django using the Django Rest Framework:

from rest_framework import serializers
from .models import CustomObject

class CustomObjectSerializer(serializers.ModelSerializer):
    class Meta:
        model = CustomObject
        fields = '__all__'

class CustomObjectListSerializer(serializers.ListSerializer):
    def create(self, validated_data):
        custom_objects = [CustomObject(**item) for item in validated_data]
        return CustomObject.objects.bulk_create(custom_objects)

    def update(self, instance, validated_data):
        instance_mapping = {str(obj.id): obj for obj in instance}
        data_mapping = {str(item['id']): item for item in validated_data}

        ret = []
        for obj_id, data in data_mapping.items():
            obj = instance_mapping.get(obj_id, None)
            if obj is None:
                ret.append(self.child.create(data))
            else:
                ret.append(self.child.update(obj, data))

        for obj_id, obj in instance_mapping.items():
            if obj_id not in data_mapping:
                obj.delete()

        return ret

class CustomObjectViewSet(viewsets.ModelViewSet):
    queryset = CustomObject.objects.all()
    serializer_class = CustomObjectSerializer
    list_serializer_class = CustomObjectListSerializer

    def get_serializer_class(self):
        if self.action == 'list':
            return self.list_serializer_class
        return self.serializer_class

In this example, we define a custom serializer for the CustomObject model using the ModelSerializer class provided by Django Rest Framework. We then define a custom list serializer CustomObjectListSerializer that overrides the create and update methods to handle creating and updating a list of objects.

Finally, we define a CustomObjectViewSet that uses the custom list serializer for the list action and the standard serializer for all other actions. This allows us to handle creating and updating a list of objects using the custom list serializer and handle all other actions using the standard serializer.