It would be nice if Django were to cache the reverse value of foreign keys when they're looked up. That might not be entirely clear, so let me give an example:
class Company(Model):
name = models.CharField(maxlength=100)
class Employee(Model):
company = models.ForeignKey(Company)
c = Company.objects.all()[0]
e = c.employee_set.all()[0]
# e now really must have a company of c... there's no reason it wouldn't be c
e.company # accesses the database
I tried implementing this, but got lost in some of the model code. My approach was to use an auto_cache 'filter' for QuerySets?. The above code would look like this:
c = Company.objects.all()[0]
e = c.employee_set.auto_cache(company=c).all()[0]
e.company # no database accesses
Which eventually I would have made automatic for all sets. I got far enough to realize that each foreign key will potentially query the database even after an attribute has explicitly been assigned. For example:
c = Company.objects.all()[0]
e = c.employee_set.all()[0]
new_company = Company()
e.company = new_company
e.company == new_company # database accesses for e.company and not equal to the new object
I'd love to see a feature like this, so if it's not something that you all want to implement, point me in the right direction.
