from django.test import TestCase

from regressiontests.null_fk.models import *

class NullFkTests(TestCase):

    def test_null_fk(self):
        d = SystemDetails.objects.create(details='First details')
        s = SystemInfo.objects.create(system_name='First forum', system_details=d)
        f = Forum.objects.create(system_info=s, forum_name='First forum')
        p = Post.objects.create(forum=f, title='First Post')
        c1 = Comment.objects.create(post=p, comment_text='My first comment')
        c2 = Comment.objects.create(comment_text='My second comment')

        # Starting from comment, make sure that a .select_related(...) with a specified
        # set of fields will properly LEFT JOIN multiple levels of NULLs (and the things
        # that come after the NULLs, or else data that should exist won't). Regression
        # test for #7369.
        c = Comment.objects.select_related().get(id=c1.id)
        self.assertEqual(c.post, p)
        self.assertEqual(Comment.objects.select_related().get(id=c2.id).post, None)

        self.assertQuerysetEqual(
            Comment.objects.select_related('post__forum__system_info').all(),
            [
                (c1.id, u'My first comment', '<Post: First Post>'),
                (c2.id, u'My second comment', 'None')
            ],
            transform = lambda c: (c.id, c.comment_text, repr(c.post))
        )

        # Regression test for #7530, #7716.
        self.assertTrue(Comment.objects.select_related('post').filter(post__isnull=True)[0].post is None)

        self.assertQuerysetEqual(
            Comment.objects.select_related('post__forum__system_info__system_details'),
            [
                (c1.id, u'My first comment', '<Post: First Post>'),
                (c2.id, u'My second comment', 'None')
            ],
            transform = lambda c: (c.id, c.comment_text, repr(c.post))
        )