FOREIGN KEY constraint failed on deleting objects - django

Question

When I am going to delete product from my cart it gives me error FOREIGN KEY constraint failed
class Cart(TimeStamp):
user = models.ForeignKey('authentication.User', on_delete=models.CASCADE, related_name='user_carts', null=True)
product = models.ForeignKey(Product, on_delete=models.CASCADE, null=True, blank=True)
sub_total_price = models.DecimalField(max_digits=100, decimal_places=2, blank=True, null=True)
quantity = models.PositiveIntegerField(default=1)
here is model first I thought the problem would be on_delete and I changed it to SET_NULL but it was useless and it did not work, I tried to delete all files from migrations folder it also did not solve my problem.
here is views.py
class CartUpdateDestroyView(generics.RetrieveUpdateDestroyAPIView):
queryset = Cart.objects.all()
serializer_class = CartSerializer
permission_classes = (IsOwnerOrAdmin,)
lookup_field = 'id'
def get_queryset(self):
return Cart.objects.filter(user=self.request.user)
in this view except Destroy all are working properly but I cannot delete the object. Any idea please?

Answer 1

views.py
def cart_update(request):
product_id = request.POST.get('product_id')
if product_id is not None:
try:
product_obj = Product.objects.get(id=product_id)
except Product.DoesNotExist:
print("Show message to user, product is gone?")
return redirect("cart:home")
cart_obj, new_obj = Cart.objects.new_or_get(request)
if product_obj in cart_obj.products.all():
cart_obj.products.remove(product_obj)
added = False
else:
cart_obj.products.add(product_obj) # cart_obj.products.add(product_id)
added = True
request.session['cart_items'] = cart_obj.products.count()
# return redirect(product_obj.get_absolute_url())
if request.is_ajax(): # Asynchronous JavaScript And XML / JSON
print("Ajax request")
json_data = {
"added": added,
"removed": not added,
"cartItemCount": cart_obj.products.count()
}
return JsonResponse(json_data)
return redirect("cart:home")
models.py
class Cart(models.Model):
user = models.ForeignKey(User, null=True, blank=True)
products = models.ManyToManyField(Product, blank=True)
subtotal = models.DecimalField(default=0.00, max_digits=100, decimal_places=2)
total = models.DecimalField(default=0.00, max_digits=100, decimal_places=2)
updated = models.DateTimeField(auto_now=True)
timestamp = models.DateTimeField(auto_now_add=True)
total1 = models.DecimalField(default=0.00, max_digits=100, decimal_places=2)
objects = CartManager()
def __str__(self):
return str(self.id)