from django.test import TestCase

from django.core.exceptions import FieldError

from regressiontests.null_queries.models import *

class NullQueriesTests(TestCase):

    def test_none_as_null(self):

        """

        Regression test for the use of None as a query value.

        None is interpreted as an SQL NULL, but only in __exact queries.

        Set up some initial polls and choices

        """

        p1 = Poll(question='Why?')

        p1.save()

        c1 = Choice(poll=p1, choice='Because.')

        c1.save()

        c2 = Choice(poll=p1, choice='Why Not?')

        c2.save()

        # Exact query with value None returns nothing ("is NULL" in sql,

        # but every 'id' field has a value).

        self.assertQuerysetEqual(Choice.objects.filter(choice__exact=None), [])

        # Excluding the previous result returns everything.

        self.assertQuerysetEqual(

                Choice.objects.exclude(choice=None).order_by('id'),

                [

                    '<Choice: Choice: Because. in poll Q: Why? >',

                    '<Choice: Choice: Why Not? in poll Q: Why? >'

                ]

        )

        # Valid query, but fails because foo isn't a keyword

        self.assertRaises(FieldError, Choice.objects.filter, foo__exact=None)

        # Can't use None on anything other than __exact

        self.assertRaises(ValueError, Choice.objects.filter, id__gt=None)

        # Can't use None on anything other than __exact

        self.assertRaises(ValueError, Choice.objects.filter, foo__gt=None)

        # Related managers use __exact=None implicitly if the object hasn't been saved.

        p2 = Poll(question="How?")

        self.assertEquals(repr(p2.choice_set.all()), '[]')

    def test_reverse_relations(self):

        """

        Querying across reverse relations and then another relation should

        insert outer joins correctly so as not to exclude results.

        """

        obj = OuterA.objects.create()

        self.assertQuerysetEqual(

            OuterA.objects.filter(inner__second=None),

            ['<OuterA: OuterA object>']

        )

        self.assertQuerysetEqual(

            OuterA.objects.filter(inner__second__data=None),

            ['<OuterA: OuterA object>']

        )

        inner_obj = Inner.objects.create(first=obj)

        self.assertQuerysetEqual(

            Inner.objects.filter(first__inner__second=None),

            ['<Inner: Inner object>']

        )