This question is similar to Atomic operations in Django? however for Django 1.4. I'm wondering if there is a way to do this without resorting to "raw SQL". My setup is a little different then his so I'll explain.
I have a record for a User and a generic table called UserRecords. Here's the definition for UserRecord.
class UserRecord (models.Model):
"""
User record model for :class:`User` users to keep
aux data like services connected, latest stats, and other accounts.
"""
def __unicode__ (self):
return u"{0}.{1}.{2}.{3}".format(self.user, self.parent, self.key, self.value)
def update_maybe_save (self, val):
if self.value != val:
self.value = val
self.save()
#: :class`User` who owns this record
user = models.ForeignKey("User")
parent = models.CharField(max_length=255, blank=True, null=True, db_index=True)
key = models.CharField(max_length=255, db_index=True)
value = models.TextField(blank=True, null=True)
As you can see, it's a very generic k/v store table with the optional parent attribute that's useful for grouping records together and optimizing some searches. It's very useful when, in this case, we want to add a couple alias's for a user.
# Inside the User model
def add_alias (self, name):
try:
UserRecord.objects.get(user=self, parent="alias", key=name, value=self.username)
except UserRecord.DoesNotExist:
UserRecord(user=self, parent="alias", key=name, value=self.username).save()
This sets ourselves up for a race condition where if a user enters the same alias twice it could create two identical records. Then each UserRecord.objects.get call fails because there are two, I get a Django error email, and I manually go fix the database.
I can't find anything in the documentation that allows me to create something atomically. Any ideas apart from the raw sql mentioned in the other question?
