Fixed #8076: fixed `get_(next/previous)_by_date` when used with subclasses....

        if hasattr(value, 'as_sql'):

            sql, params = value.as_sql()

            return QueryWrapper(('(%s)' % sql), params)

        if lookup_type == 'exact':

        # FIXME: lt and gt are explicitally allowed to make

        # get_(next/prev)_by_date work; other lookups are not allowed since that

        # gets messy pretty quick. This is a good candidate for some refactoring

        # in the future.

        if lookup_type in ['exact', 'gt', 'lt']:

            return [pk_trace(value)]

        if lookup_type in ('range', 'in'):

            return [pk_trace(v) for v in value]

class SelfRefChild(SelfRefParent):

    child_data = models.IntegerField()

class Article(models.Model):

    headline = models.CharField(max_length=100)

    pub_date = models.DateTimeField()

    class Meta:

        ordering = ('-pub_date', 'headline')

    def __unicode__(self):

        return self.headline

class ArticleWithAuthor(Article):

    author = models.CharField(max_length=100) 

__test__ = {'API_TESTS':"""

# Regression for #7350, #7202

# Check that when you create a Parent object with a specific reference to an

>>> obj = SelfRefChild.objects.create(child_data=37, parent_data=42)

>>> obj.delete()

# Regression tests for #8076 - get_(next/previous)_by_date should 

>>> c1 = ArticleWithAuthor(headline='ArticleWithAuthor 1', author="Person 1", pub_date=datetime.datetime(2005, 8, 1, 3, 0))

>>> c1.save()

>>> c2 = ArticleWithAuthor(headline='ArticleWithAuthor 2', author="Person 2", pub_date=datetime.datetime(2005, 8, 1, 10, 0))

>>> c2.save()

>>> c3 = ArticleWithAuthor(headline='ArticleWithAuthor 3', author="Person 3", pub_date=datetime.datetime(2005, 8, 2))

>>> c3.save()

>>> c1.get_next_by_pub_date()

<ArticleWithAuthor: ArticleWithAuthor 2>

>>> c2.get_next_by_pub_date()

<ArticleWithAuthor: ArticleWithAuthor 3>

>>> c3.get_next_by_pub_date()

Traceback (most recent call last):

    ...

DoesNotExist: ArticleWithAuthor matching query does not exist.

>>> c3.get_previous_by_pub_date()

<ArticleWithAuthor: ArticleWithAuthor 2>

>>> c2.get_previous_by_pub_date()

<ArticleWithAuthor: ArticleWithAuthor 1>

>>> c1.get_previous_by_pub_date()

Traceback (most recent call last):

    ...

DoesNotExist: ArticleWithAuthor matching query does not exist.

"""}