Can Django models use MySQL functions?

Question

Is there a way to force Django models to pass a field to a MySQL function every time the model data is read or loaded? To clarify what I mean in SQL, I want the Django model to

Answer 1

Here is a working solution, based in part on (http://www.djangosnippets.org/snippets/824/):

class Employee(models.Model):
   social_security_number = models.CharField(max_length=32)

   def _get_ssn(self):
       cursor = connection.cursor()
       cursor.execute("SELECT AES_DECRYPT(UNHEX(social_security_number), %s) as ssn FROM tablename WHERE id=%s", [settings.SECRET_KEY, self.id])
       return cursor.fetchone()[0]

   def _set_ssn(self, ssn_value):
       cursor = connection.cursor()
       cursor.execute("SELECT HEX(AES_ENCRYPT(%s, %s)) as ssn", [ssn_value, settings.SECRET_KEY])
       self.social_security_number = cursor.fetchone()[0]

   ssn = property(_get_ssn, _set_ssn)

And the results:

>>> from foo.bar.models import Employee
>>> p=Employee.objects.create(ssn='123-45-6789')
>>> p.ssn
'123-45-6789'

mysql> select * from foo_employee;
+----+----------------------------------+
| id | social_security_number           |
+----+----------------------------------+
| 31 | 41DF2D946C9186BEF77DD3307B85CC8C |
+----+----------------------------------+
1 row in set (0.00 sec)