# coding: utf-8
"""
models utils
~~~~~~~~~~~~
Last commit info:
~~~~~~~~~~~~~~~~~
$LastChangedDate$
$Rev$
$Author:$
:copyleft: 2009 by the django-tools team, see AUTHORS for more details.
:license: GNU GPL v3 or above, see LICENSE for more details.
"""
from django.conf import settings
from django.db.models import signals
from django.utils.text import get_text_list
from django.db import connection,IntegrityError
from django.utils.translation import ugettext
from django.db.models.fields import FieldDoesNotExist
def check_unique_together(sender, **kwargs):
"""
Check models unique_together manually. Django enforced unique together only the database level, but
some databases (e.g. SQLite) doesn't support this.
usage:
from django.db.models import signals
signals.pre_save.connect(check_unique_together, sender=MyModelClass)
or use auto_add_check_unique_together(), see below.
"""
instance = kwargs["instance"]
for field_names in sender._meta.unique_together:
model_kwargs = {}
for field_name in field_names:
try:
data = getattr(instance, field_name)
except FieldDoesNotExist:
# e.g.: a missing field, which is however necessary.
# The real exception on model creation should be raised.
continue
model_kwargs[field_name] = data
query_set = sender.objects.filter(**model_kwargs)
if instance.pk != None:
# Exclude the instance if it was saved in the past
query_set = query_set.exclude(pk=instance.pk)
count = query_set.count()
if count > 0:
field_names = get_text_list(field_names, _('and'))
msg = _(u"%(model_name)s with this %(field_names)s already exists.") % {
'model_name': unicode(instance.__class__.__name__),
'field_names': unicode(field_names)
}
raise IntegrityError(msg)
def auto_add_check_unique_together(model_class):
"""
Add only the signal handler check_unique_together, if a database without UNIQUE support is used.
"""
if settings.DATABASE_ENGINE in ('sqlite3',): # 'postgresql', 'mysql', 'sqlite3' or 'ado_mssql'.
signals.pre_save.connect(check_unique_together, sender=model_class)
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