from django.core.exceptions import FieldError

from django.test import TestCase

from .models import Choice, Poll, User

class ReverseLookupTests(TestCase):

    @classmethod

    def setUpTestData(cls):

        john = User.objects.create(name="John Doe")

        jim = User.objects.create(name="Jim Bo")

        first_poll = Poll.objects.create(

            question="What's the first question?", creator=john

        )

        second_poll = Poll.objects.create(

            question="What's the second question?", creator=jim

        )

        Choice.objects.create(

            poll=first_poll, related_poll=second_poll, name="This is the answer."

        )

    def test_reverse_by_field(self):

        u1 = User.objects.get(poll__question__exact="What's the first question?")

        self.assertEqual(u1.name, "John Doe")

        u2 = User.objects.get(poll__question__exact="What's the second question?")

        self.assertEqual(u2.name, "Jim Bo")

    def test_reverse_by_related_name(self):

        p1 = Poll.objects.get(poll_choice__name__exact="This is the answer.")

        self.assertEqual(p1.question, "What's the first question?")

        p2 = Poll.objects.get(related_choice__name__exact="This is the answer.")

        self.assertEqual(p2.question, "What's the second question?")

    def test_reverse_field_name_disallowed(self):

        """

        If a related_name is given you can't use the field name instead

        """

        msg = (

            "Cannot resolve keyword 'choice' into field. Choices are: "

            "creator, creator_id, id, poll_choice, question, related_choice"

        )

        with self.assertRaisesMessage(FieldError, msg):

            Poll.objects.get(choice__name__exact="This is the answer")