nested objects in Django rest framework

Question

I want to design solution for ordering items. I have endpoint that create orders BUT I need to to have items object in the order. let me show you the code

class ItemModel(models.Model):
    name = models.CharField(max_length=50)
    price = models.FloatField()
    discretion = models.CharField(max_length=500)
    available = models.BooleanField(default=True)

class OrderModel(models.Model):
    phone = models.CharField(max_length=20)
    delevary_time = models.DateTimeField()

class CartModel(models.Model):
    order = models.ForeignKey(OrderModel, on_delete=models.CASCADE, related_name='order_m')
    item = models.ForeignKey(ItemModel, on_delete=models.CASCADE, related_name='item_m')

I need endpoint that create order to me. her what I did

class CartSerializer(serializers.ModelSerializer):
    class Meta:
        model = CartModel
        exclude = ['order',]
        depth = 2

class OrderSerializer(serializers.ModelSerializer):
    cart = serializers.SerializerMethodField()
    class Meta:
        model = OrderModel
        fields = ['phone', 'state', 'delevary_time', 'cart']

    def get_cart(self, obj):
        cart = CartModel.objects.filter(order__id=obj.id)
        serializer = CartSerializer(cart, many=True)
        return serializer.data

this is the endpoint

      router.register('order', OrderViewSet, 'api-order')
{
    "phone": 124997988698,
    "delevary_time": "2020-07-17T19:34:00",
    "cart": [
        {
            "item": 1
        },
        {
            "item": 2
        }
    ]
}

when I post the json it don't save the cart it only save the oder phone and delevary_time. How I can save the cart at the same time

It's to better use nested serializer for foreignkeys, but not SerializerMethodField, since it is readonly — minglyu
– minglyu, Commented Jul 18, 2020 at 8:33
full example here -> django-rest-framework.org/api-guide/relations/… — minglyu
– minglyu, Commented Jul 18, 2020 at 9:41
it give me this error python Original exception text was: 'OrderModel' object has no attribute 'cart'. — prg.dev
– prg.dev, Commented Jul 18, 2020 at 10:14
i found that it save the model but the problem in Get request. I'don't know way !!.. Also, in Post request it save the model and show error message — prg.dev
– prg.dev, Commented Jul 18, 2020 at 10:26

prg.dev · Accepted Answer · 2020-07-18 10:33:41Z

1

class CartSerializer(serializers.ModelSerializer):
    class Meta:
        model = CartModel
        exclude = ['order',]
        depth = 2

class OrderSerializer(serializers.ModelSerializer):
    order_m = CartSerializer(many=True) # adding this
    class Meta:
        model = OrderModel
        fields = ['phone', 'state', 'delevary_time', 'order_m']
    
     def create(self, validated_data):
        cart_data = validated_data.pop('order_m')
        order = OrderModel.objects.create(**validated_data)
        for c in cart_data:
            CartModel.objects.create(order=order, **c)
        return order

answered Jul 18, 2020 at 10:33

prg.dev

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