from datetime import datetime

from operator import attrgetter

from django.test import TestCase

from models import Article

class OrderingTests(TestCase):

    def test_basic(self):

        a1 = Article.objects.create(

            headline="Article 1", pub_date=datetime(2005, 7, 26)

        )

        a2 = Article.objects.create(

            headline="Article 2", pub_date=datetime(2005, 7, 27)

        )

        a3 = Article.objects.create(

            headline="Article 3", pub_date=datetime(2005, 7, 27)

        )

        a4 = Article.objects.create(

            headline="Article 4", pub_date=datetime(2005, 7, 28)

        )

        # By default, Article.objects.all() orders by pub_date descending, then

        # headline ascending.

        self.assertQuerysetEqual(

            Article.objects.all(), [

                "Article 4",

                "Article 2",

                "Article 3",

                "Article 1",

            ],

            attrgetter("headline")

        )

        # Override ordering with order_by, which is in the same format as the

        # ordering attribute in models.

        self.assertQuerysetEqual(

            Article.objects.order_by("headline"), [

                "Article 1",

                "Article 2",

                "Article 3",

                "Article 4",

            ],

            attrgetter("headline")

        )

        self.assertQuerysetEqual(

            Article.objects.order_by("pub_date", "-headline"), [

                "Article 1",

                "Article 3",

                "Article 2",

                "Article 4",

            ],

            attrgetter("headline")

        )

        # Only the last order_by has any effect (since they each override any

        # previous ordering).

        self.assertQuerysetEqual(

            Article.objects.order_by("id"), [

                "Article 1",

                "Article 2",

                "Article 3",

                "Article 4",

            ],

            attrgetter("headline")

        )

        self.assertQuerysetEqual(

            Article.objects.order_by("id").order_by("-headline"), [

                "Article 4",

                "Article 3",

                "Article 2",

                "Article 1",

            ],

            attrgetter("headline")

        )

        # Use the 'stop' part of slicing notation to limit the results.

        self.assertQuerysetEqual(

            Article.objects.order_by("headline")[:2], [

                "Article 1",

                "Article 2",

            ],

            attrgetter("headline")

        )

        # Use the 'stop' and 'start' parts of slicing notation to offset the

        # result list.

        self.assertQuerysetEqual(

            Article.objects.order_by("headline")[1:3], [

                "Article 2",

                "Article 3",

            ],

            attrgetter("headline")

        )

        # Getting a single item should work too:

        self.assertEqual(Article.objects.all()[0], a4)

        # Use '?' to order randomly.

        self.assertEqual(

            len(list(Article.objects.order_by("?"))), 4

        )

        # Ordering can be reversed using the reverse() method on a queryset.

        # This allows you to extract things like "the last two items" (reverse

        # and then take the first two).

        self.assertQuerysetEqual(

            Article.objects.all().reverse()[:2], [

                "Article 1",

                "Article 3",

            ],

            attrgetter("headline")

        )

        # Ordering can be based on fields included from an 'extra' clause

        self.assertQuerysetEqual(

            Article.objects.extra(select={"foo": "pub_date"}, order_by=["foo", "headline"]), [

                "Article 1",

                "Article 2",

                "Article 3",

                "Article 4",

            ],

            attrgetter("headline")

        )

        # If the extra clause uses an SQL keyword for a name, it will be

        # protected by quoting.

        self.assertQuerysetEqual(

            Article.objects.extra(select={"order": "pub_date"}, order_by=["order", "headline"]), [

                "Article 1",

                "Article 2",

                "Article 3",

                "Article 4",

            ],

            attrgetter("headline")

        )