i am trying to insert data into my OrderItem() model:

class OrderItem(models.Model):
   user = models.ForeignKey(settings.AUTH_USER_MODEL,
                         on_delete=models.CASCADE)
   ordered = models.BooleanField(default=False)
   item = models.ForeignKey(Item, on_delete=models.CASCADE)
   quantity = models.IntegerField(default=1)

with an api with json data as follows:

{ "username": "admin",
      "item": "Kavya",
      "quantity": "1"
    }

and i my view i am recieving this data and updating like:

class addtoCart(APIView):
# permission_classes=[IsAuthenticated,]
# authentication_classes=[TokenAuthentication,]
def post(self,request):
     username=request.data["username"]
     itemname=request.data["item"]
     quant=request.data["quantity"]
     #inserting data to cart
     article = OrderItem()
     article.User = username
     article.Item = itemname
     article.quantity=quant
     article.save()
     
     query=OrderItem.objects.filter(user=username)
     serializers=OrderItemSerializer(query,many=True)
     return Response(serializers.data)

but whenever i try to do so i get an error:

IntegrityError at /apis/addtoCart NOT NULL constraint failed: core_orderitem.item_id

i dont know what causing this error can someone please help <3.

CodePudding user response：

You need to pass an id or other unique constraint in your request body, so that you can identify which Item object to set to the article instance, e.g.:

{
    "username": "admin",
    "item_id": <id>,
    "quantity": "1"
}

and in your post method:

from django.shortcuts import get_object_or_404

def post(self,request):
    username = request.data["username"]
    item_id = request.data["item_id"]
    quant = request.data["quantity"]

    # since `user` is also a foreign key reference i would suggest you to query it, too
    user = get_object_or_404(User, username=username)

    article = OrderItem()
    # set the attributes as lowercase
    article.user = user

    # Django creates an extra field `<foreign_key>_id` for related objects, so that you can set it without querying
    article.item_id = item_id
    article.quantity = quant
    article.save()

    # ...

But I would suggest you using DRF Serializers for dealing with request.data.