class ProductInOrder(models.Model):
    Order = models.ForeignKey(Order, on_delete=models.CASCADE, blank=True, null=True, default=None)
    Product = models.ForeignKey(Product, on_delete=models.CASCADE)
    is_active = models.BooleanField(default=True)
    Count = models.IntegerField(default=1)
    #Prices = models.ForeignKey(PriceOfProduct, on_delete=None, blank=True, null=True, default=None)
    Price = models.DecimalField(max_digits=12, decimal_places=2, default=Decimal('0.00'))
    Summa = models.DecimalField(max_digits=12, decimal_places=2, default=Decimal('0.00'))

def product_of_order_post_save(sender,instance,create,**kwargs):
    order = instance.Order
    order_total = 0

    all_product_in_order = ProductInOrder.objects.filter(Order=order,is_active=True)


    for item in all_product_in_order:
        #TypePrices = self.Pirces.TypePrices
        #Prices = self.Pirces
        mProduct = item.Product
        mType = TypePrices.objects.get(id=3)
        # вибираємо всі товари з з типом ціни 1 запис, по замовчуванні
        PirceForProductType = PriceOfProduct.objects.filter(Product=mProduct, TypePrices=mType)
        # Вибираємо тепер максимальної датою тобто останні актуальні ціни
        LastPrice = PirceForProductType.avarage(models.Max("Date"))
        item.Price = LastPrice.Price
        item.Summa = item.Price*item.Count
        order_total += item.Summa
        instance.save()
        instance.Order.Summa = order_total
        instance.Order.save(force_update=True)

    assert isinstance(post_save.connect, object)
    post_save.connect(product_of_order_post_save,ProductInOrder)


def save(*args, self, **kwargs):
    self.Summa = 300.05
    super(ProductInOrder, self).save(*args, **kwargs)