from django.db.models import Q

from django.test import TestCase

from .models import Comment, Forum, Item, Post, PropertyValue, SystemDetails, SystemInfo

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.assertIsNone(Comment.objects.select_related().get(id=c2.id).post)

        self.assertQuerysetEqual(

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

            [

                (c1.id, "My first comment", "<Post: First Post>"),

                (c2.id, "My second comment", "None"),

            ],

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

        )

        # Regression test for #7530, #7716.

        self.assertIsNone(

            Comment.objects.select_related("post").filter(post__isnull=True)[0].post

        )

        self.assertQuerysetEqual(

            Comment.objects.select_related("post__forum__system_info__system_details"),

            [

                (c1.id, "My first comment", "<Post: First Post>"),

                (c2.id, "My second comment", "None"),

            ],

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

        )

    def test_combine_isnull(self):

        item = Item.objects.create(title="Some Item")

        pv = PropertyValue.objects.create(label="Some Value")

        item.props.create(key="a", value=pv)

        item.props.create(key="b")  # value=NULL

        q1 = Q(props__key="a", props__value=pv)

        q2 = Q(props__key="b", props__value__isnull=True)

        # Each of these individually should return the item.

        self.assertEqual(Item.objects.get(q1), item)

        self.assertEqual(Item.objects.get(q2), item)

        # Logically, qs1 and qs2, and qs3 and qs4 should be the same.

        qs1 = Item.objects.filter(q1) & Item.objects.filter(q2)

        qs2 = Item.objects.filter(q2) & Item.objects.filter(q1)

        qs3 = Item.objects.filter(q1) | Item.objects.filter(q2)

        qs4 = Item.objects.filter(q2) | Item.objects.filter(q1)

        # Regression test for #15823.

        self.assertEqual(list(qs1), list(qs2))

        self.assertEqual(list(qs3), list(qs4))