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=1)

        self.assertEquals(c.post, p)

        self.assertEquals(Comment.objects.select_related().get(id=2).post, None)

        self.assertQuerysetEqual(

            Comment.objects.select_related('post__forum__system_info').all(),

            [

                (1, u'My first comment', '<Post: First Post>'),

                (2, 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'),

            [

                (1, u'My first comment', '<Post: First Post>'),

                (2, u'My second comment', 'None')

            ],

            transform = lambda c: (c.id, c.comment_text, repr(c.post))

        )