django1/django/contrib/sites/management.py

"""
Creates the default Site object.
"""

from django.apps import apps
from django.core.management.color import no_style
from django.db import DEFAULT_DB_ALIAS, connections, router
from django.db.models import signals


def create_default_site(app_config, verbosity=2, interactive=True, db=DEFAULT_DB_ALIAS, **kwargs):
    try:
        Site = apps.get_model('sites', 'Site')
    except LookupError:
        return

    if not router.allow_migrate(db, Site):
        return

    if not Site.objects.exists():
        # The default settings set SITE_ID = 1, and some tests in Django's test
        # suite rely on this value. However, if database sequences are reused
        # (e.g. in the test suite after flush/syncdb), it isn't guaranteed that
        # the next id will be 1, so we coerce it. See #15573 and #16353. This
        # can also crop up outside of tests - see #15346.
        if verbosity >= 2:
            print("Creating example.com Site object")
        Site(pk=1, domain="example.com", name="example.com").save(using=db)

        # We set an explicit pk instead of relying on auto-incrementation,
        # so we need to reset the database sequence. See #17415.
        sequence_sql = connections[db].ops.sequence_reset_sql(no_style(), [Site])
        if sequence_sql:
            if verbosity >= 2:
                print("Resetting sequence")
            cursor = connections[db].cursor()
            for command in sequence_sql:
                cursor.execute(command)

        Site.objects.clear_cache()


signals.post_migrate.connect(create_default_site, sender=apps.get_app_config('sites'))