Annotate a sum of two fields multiplied

Question

I have three models, simplified for the example:

class Customer(models.Model):
    email = models.CharField(max_length=128)

class Order(models.Model):
    custo         


        

Answer 1

I just ran into this and I don't think that annotate and will work with a property, see Django - Can you use property as the field in an aggregation function?

Here is what I did.

class Customer(models.Model):
    email = models.CharField(max_length=128)

class Order(models.Model):
    customer = models.ForeignKey(Customer)
    order_status = models.CharField(blank=True, max_length=256)

class Lineitem(models.Model):
    order = models.ForeignKey(Order)
    quantity = models.IntegerField(blank=True)
    price = models.DecimalField(max_digits=6, decimal_places=2)
    @property
    def total(self):
        return self.quantity * self.price

Then use sum and a list comprehension:

sum([li.total for li in  LineItem.objects.filter(order__customer=some_customer).filter(somefilter)])