python - queryset django relationship -

i have 2 models:

class income(models.model):     id = models.autofield('id', primary_key=true)     date = models.datefield('date', blank=true, null=true)     user = models.foreignkey(user, null=true, help_text="user income")  class invoice(models.model):     id = models.autofield('id', primary_key=true)     income = models.foreignkey(income, null=true, blank=true, related_name='income')     user = models.foreignkey(user, null=true, blank=true, related_name='user_invoice') 

and need "income" not associated "invoice". find no way see problem. thank :)

filter using __isnull:

normally, django automatically follows relationship fields using lowercased name of related model:

income.objects.filter(invoice__isnull=true) 

here, you've specified related_name attribute, need use that:

income.objects.filter(income__isnull=true) 

note reveals related name attribute income fk on invoice backwards. see no reason setting related_name @ all, if need 1 should describe how invoices related incomes, not vice versa.