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Singletons

SingletonModel models a settings-style object that logically exists once: site-wide settings, a footer configuration, and so on.

from blueprint.models import SingletonModel


class SiteSettings(SingletonModel):
    site_name = models.CharField(max_length=200)
    maintenance_mode = models.BooleanField(default=False)

SingletonManager​

objects is a SingletonManager with singleton-aware behavior:

  • get() ignores its arguments and returns the single instance, or None when the table is empty.
  • create() creates the instance if it does not exist, otherwise updates it.
settings = SiteSettings.objects.get()             # None or the instance
settings = SiteSettings.objects.create(site_name="My site")
settings = SiteSettings.objects.create(site_name="New name")  # updates
SiteSettings.objects.count()                       # 1

The single-row guarantee is enforced at the database level with a unique constant column, so it also holds under concurrent writes — save() on a second instance raises IntegrityError.