{
    "items": {
        12: {
            "name": "item 1"
        },
        66: {
            "name": "item 2"
        }
    }
}

{
    "items": [
        {
            "name": "item 1",
            "id": 12
        }, {
            "name": "item 2"
            "id": 66
        }
    ]
}

class ItemSerializer(serializers.Serializer):
    id = serializers.IntegerField()
    name = serializers.CharField()

class ItemsSerializer(serializers.Serializer):
    items = serializers.ListField(child=ItemSerializer())

class ItemsSerializer(serializers.Serializer):
    items = ItemSerializer(many=True)