from django.db import models
from django.db.models import F
class Counter(models.Model):
"For generating unique IDs"
key = models.CharField(max_length=50, primary_key=True)
counter = models.IntegerField(default = 0)
@classmethod
def next(cls, key = 'default'):
"Increments and returns the next unused integer"
try:
cls.objects.filter(pk = key).update(counter = F('counter') + 1)
return cls.objects.get(pk = key).counter
except cls.DoesNotExist:
# This could raise an integrity error in a race condition :/
return cls.objects.create(key = key, counter = 0).counter
@classmethod
def next_hex(cls, key = 'default'):
return hex(cls.next(key)).replace('0x', '').replace('L', '')
def __unicode__(self):
return u'%s = %s' % (self.pk, self.counter)
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Comments
Excelents, congratulations
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