Question

When I build a model in Django, I add the following information:

def __unicode__(self):
  return self.some_field

class Meta:
  ordering = ['some_field_to_order_by']

Is it possible to set ordering based on a sort of if/else scenario?

For example, I have a customer model which, for sake of argument, has these fields:

first_name
last_name
company_name
is_company (boolean)

If the customer is a Company, I only add information to the company_name field and set is_company=True, leaving the other two blank. If the customer is a person, then I add information to the first_name and last_name fields, leaving the company_name blank and the is_company=False.

I want to sort these records by last_name if the is_company field is False and company_name if is_company is True.

Is this possible?

EDIT For an example (per request, sort of)

For my app, this customer table holds information regarding owners of security systems. Sometimes, a security system is installed in a residential setting. In this case, the owner of the system is a person — thus, I would enter the first_name and last_name into the customer record. Sometimes the system is installed in a commercial setting, therefore the owner is a company. For this I enter only the company_name field, leaving the other fields blank.

Now, when I provide an estimate for a NEW security system installation, I can provide the estimate to a new customer or an existing customer (existing customer, but a new location for them). When it is an existing customer, I have a drop down box that lists all existing customers (ALL RECORDS in the customer table).

THIS is where I want all the records to be ordered properly. As it is now, I get a jumbled mess of hundreds of records making it brutal to find the existing owner.

Hopefully this helps with what I’m trying to achieve.

Answer 1

You can create a custom manager, which will do what you want.

class CompanyFilter(models.Manager):
   def get_query_set(self):
        qs = super(CompanyFilter, self).get_query_set()
        return qs.filter(is_company=True).order_by('company_name')

class PersonFilter(models.Manager):
   def get_query_set(self):
        qs = super(PersonFilter, self).get_query_set()
        return qs.filter(is_company=False).order_by('last_name')

class Contact(models.Model):
   # ... your regular fields

   companies = CompanyFilter()
   people = PersonFilter()


all_companies = Contact.companies.all()
all_people = Contact.people.all()
all_contacts = Contact.objects.all()