from django.db.models import Q

from django.http import Http404

from django.shortcuts import get_list_or_404, get_object_or_404

from django.test import TestCase

from .models import Article, Author

class GetObjectOr404Tests(TestCase):

    def test_get_object_or_404(self):

        a1 = Author.objects.create(name="Brave Sir Robin")

        a2 = Author.objects.create(name="Patsy")

        # No Articles yet, so we should get an Http404 error.

        with self.assertRaises(Http404):

            get_object_or_404(Article, title="Foo")

        article = Article.objects.create(title="Run away!")

        article.authors.set([a1, a2])

        # get_object_or_404 can be passed a Model to query.

        self.assertEqual(get_object_or_404(Article, title__contains="Run"), article)

        # We can also use the Article manager through an Author object.

        self.assertEqual(

            get_object_or_404(a1.article_set, title__contains="Run"), article

        )

        # No articles containing "Camelot". This should raise an Http404 error.

        with self.assertRaises(Http404):

            get_object_or_404(a1.article_set, title__contains="Camelot")

        # Custom managers can be used too.

        self.assertEqual(

            get_object_or_404(Article.by_a_sir, title="Run away!"), article

        )

        # QuerySets can be used too.

        self.assertEqual(

            get_object_or_404(Article.objects.all(), title__contains="Run"), article

        )

        # Just as when using a get() lookup, you will get an error if more than

        # one object is returned.

        with self.assertRaises(Author.MultipleObjectsReturned):

            get_object_or_404(Author.objects.all())

        # Using an empty QuerySet raises an Http404 error.

        with self.assertRaises(Http404):

            get_object_or_404(Article.objects.none(), title__contains="Run")

        # get_list_or_404 can be used to get lists of objects

        self.assertEqual(

            get_list_or_404(a1.article_set, title__icontains="Run"), [article]

        )

        # Http404 is returned if the list is empty.

        with self.assertRaises(Http404):

            get_list_or_404(a1.article_set, title__icontains="Shrubbery")

        # Custom managers can be used too.

        self.assertEqual(

            get_list_or_404(Article.by_a_sir, title__icontains="Run"), [article]

        )

        # QuerySets can be used too.

        self.assertEqual(

            get_list_or_404(Article.objects.all(), title__icontains="Run"), [article]

        )

        # Q objects.

        self.assertEqual(

            get_object_or_404(

                Article,

                Q(title__startswith="Run") | Q(title__startswith="Walk"),

                authors__name__contains="Brave",

            ),

            article,

        )

        self.assertEqual(

            get_list_or_404(

                Article,

                Q(title__startswith="Run") | Q(title__startswith="Walk"),

                authors__name="Patsy",

            ),

            [article],

        )

    def test_bad_class(self):

        # Given an argument klass that is not a Model, Manager, or Queryset

        # raises a helpful ValueError message

        msg = (

            "First argument to get_object_or_404() must be a Model, Manager, or "

            "QuerySet, not 'str'."

        )

        with self.assertRaisesMessage(ValueError, msg):

            get_object_or_404("Article", title__icontains="Run")

        class CustomClass:

            pass

        msg = (

            "First argument to get_object_or_404() must be a Model, Manager, or "

            "QuerySet, not 'CustomClass'."

        )

        with self.assertRaisesMessage(ValueError, msg):

            get_object_or_404(CustomClass, title__icontains="Run")

        # Works for lists too

        msg = (

            "First argument to get_list_or_404() must be a Model, Manager, or "

            "QuerySet, not 'list'."

        )

        with self.assertRaisesMessage(ValueError, msg):

            get_list_or_404([Article], title__icontains="Run")

    def test_get_object_or_404_queryset_attribute_error(self):

        """AttributeError raised by QuerySet.get() isn't hidden."""

        with self.assertRaisesMessage(AttributeError, "AttributeErrorManager"):

            get_object_or_404(Article.attribute_error_objects, id=42)

    def test_get_list_or_404_queryset_attribute_error(self):

        """AttributeError raised by QuerySet.filter() isn't hidden."""

        with self.assertRaisesMessage(AttributeError, "AttributeErrorManager"):

            get_list_or_404(Article.attribute_error_objects, title__icontains="Run")