# -*- coding: utf-8 -*-

'''

Created on Nov 14, 2014

from https://gist.github.com/gsakkis/601977

to correct https://code.djangoproject.com/ticket/10227

@author: ymh

'''

from django.core.exceptions import ObjectDoesNotExist

from django.db import models

from django.db.models import fields as django_fields

from south.modelsinspector import add_introspection_rules

class OneToOneField(models.OneToOneField):    

    def __init__(self, to, **kwargs):

        self.related_default = kwargs.pop('related_default', None)

        super(OneToOneField, self).__init__(to, **kwargs)

    def contribute_to_related_class(self, cls, related):

        setattr(cls, related.get_accessor_name(),

                SingleRelatedObjectDescriptor(related, self.related_default))

class SingleRelatedObjectDescriptor(django_fields.related.SingleRelatedObjectDescriptor):

    def __init__(self, related, default):

        super(SingleRelatedObjectDescriptor, self).__init__(related)

        self.default = default

    def __get__(self, instance, instance_type=None):

        try:

            return super(SingleRelatedObjectDescriptor, self).__get__(instance,

                                                                      instance_type)

        except ObjectDoesNotExist:

            if self.default is None:

                raise

            value = self.default(instance)

            setattr(instance, self.cache_name, value)

            if value is not None:

                setattr(value, self.related.field.get_cache_name(), instance)

            return value

add_introspection_rules([

    (

        [OneToOneField],

        [],         # Positional arguments (not used)

        {           # Keyword argument

        },

    ),

], ["^hdalab\.fields\.OneToOneField"])