if statement referencing foreign key

Question

I have django app where technicians enter service data, and if the customer is not in the list they choose "NEW" from the customer field dropdown and enter the new customer's name in the service.new_customer field rather than adding the customer. When I display it, I want to show "John's Pub" if it's an existing customer, and "NEW: John's Pub" if it's not. I can get this to work by using the id - the id for the customer called "NEW" is 1038. But, I want to be able to have the logic reference the word "NEW" rather than the id.

Here is my models.py

class Service(models.Model):
    customer = models.ForeignKey(Customer)
    new_customer = models.CharField(max_length=100, blank=True, null=True)

class Customer(models.Model):
    name = models.CharField(max_length=200)

This view.py works:

def service_view(request):
    for service in services:
        if service.customer_id == 1038:
            service.customer_combo="%s:%s"%(service.customer,service.new_customer)
        else:
            service.customer_combo="%s"%(service.customer)
return render(request,'template.html')

This view.py does not work*:

def service_view(request):
    for service in services:
        if service.customer == 'NEW':
            service.customer_combo="%s:%s"%(service.customer,service.new_customer)
        else:
            service.customer_combo="%s"%(service.customer)
return render(request,'template.html')

• When I say it doesn't work, I mean it only assigns customer.combo in the "else" condition, though there are tons of cases where the customer is NEW - it's printing "NEW" rather than "NEW:John's Pub"

How should I be constructing the 'if service.customer == 'NEW':' statement to get it to work?

Answer 1

if service.customer.name == 'NEW':

Answer 2

You are trying to compare a Customer object with the name of the customer. They are of different types and cannot be compared.

You need to do something like:

service.customer == some_customer_object # compare with model object

or

service.customer.name == 'NEW' # compare with the name

or

str(service.customer) == 'NEW' # compare with the representation of the object

Answer 3

这也有效，但我认为彼得的答案更好，只是看起来更干净

if str(service.customer) == 'NEW':