from operator import attrgetter

from django.conf import settings

from django.contrib.contenttypes.models import ContentType

from django.contrib.sessions.backends.db import SessionStore

from django.db import connection

from django.db.models.loading import cache

from django.test import TestCase

from models import ResolveThis, Item, RelatedItem, Child, Leaf

class DeferRegressionTest(TestCase):

    def assert_num_queries(self, n, func, *args, **kwargs):

        old_DEBUG = settings.DEBUG

        settings.DEBUG = True

        starting_queries = len(connection.queries)

        try:

            func(*args, **kwargs)

        finally:

            settings.DEBUG = old_DEBUG

        self.assertEqual(starting_queries + n, len(connection.queries))

    def test_basic(self):

        # Deferred fields should really be deferred and not accidentally use

        # the field's default value just because they aren't passed to __init__

        Item.objects.create(name="first", value=42)

        obj = Item.objects.only("name", "other_value").get(name="first")

        # Accessing "name" doesn't trigger a new database query. Accessing

        # "value" or "text" should.

        def test():

            self.assertEqual(obj.name, "first")

            self.assertEqual(obj.other_value, 0)

        self.assert_num_queries(0, test)

        def test():

            self.assertEqual(obj.value, 42)

        self.assert_num_queries(1, test)

        def test():

            self.assertEqual(obj.text, "xyzzy")

        self.assert_num_queries(1, test)

        def test():

            self.assertEqual(obj.text, "xyzzy")

        self.assert_num_queries(0, test)

        # Regression test for #10695. Make sure different instances don't

        # inadvertently share data in the deferred descriptor objects.

        i = Item.objects.create(name="no I'm first", value=37)

        items = Item.objects.only("value").order_by("-value")

        self.assertEqual(items[0].name, "first")

        self.assertEqual(items[1].name, "no I'm first")

        RelatedItem.objects.create(item=i)

        r = RelatedItem.objects.defer("item").get()

        self.assertEqual(r.item_id, i.id)

        self.assertEqual(r.item, i)

        # Some further checks for select_related() and inherited model

        # behaviour (regression for #10710).

        c1 = Child.objects.create(name="c1", value=42)

        c2 = Child.objects.create(name="c2", value=37)

        Leaf.objects.create(name="l1", child=c1, second_child=c2)

        obj = Leaf.objects.only("name", "child").select_related()[0]

        self.assertEqual(obj.child.name, "c1")

        self.assertQuerysetEqual(

            Leaf.objects.select_related().only("child__name", "second_child__name"), [

                "l1",

            ],

            attrgetter("name")

        )

        # Models instances with deferred fields should still return the same

        # content types as their non-deferred versions (bug #10738).

        ctype = ContentType.objects.get_for_model

        c1 = ctype(Item.objects.all()[0])

        c2 = ctype(Item.objects.defer("name")[0])

        c3 = ctype(Item.objects.only("name")[0])

        self.assertTrue(c1 is c2 is c3)

        # Regression for #10733 - only() can be used on a model with two

        # foreign keys.

        results = Leaf.objects.only("name", "child", "second_child").select_related()

        self.assertEqual(results[0].child.name, "c1")

        self.assertEqual(results[0].second_child.name, "c2")

        results = Leaf.objects.only("name", "child", "second_child", "child__name", "second_child__name").select_related()

        self.assertEqual(results[0].child.name, "c1")

        self.assertEqual(results[0].second_child.name, "c2")

        # Test for #12163 - Pickling error saving session with unsaved model

        # instances.

        SESSION_KEY = '2b1189a188b44ad18c35e1baac6ceead'

        item = Item()

        item._deferred = False

        s = SessionStore(SESSION_KEY)

        s.clear()

        s["item"] = item

        s.save()

        s = SessionStore(SESSION_KEY)

        s.modified = True

        s.save()

        i2 = s["item"]

        self.assertFalse(i2._deferred)

        # Regression for #11936 - loading.get_models should not return deferred

        # models by default.

        klasses = sorted(

            cache.get_models(cache.get_app("defer_regress")),

            key=lambda klass: klass.__name__

        )

        self.assertEqual(

            klasses, [

                Child,

                Item,

                Leaf,

                RelatedItem,

                ResolveThis,

            ]

        )

        klasses = sorted(

            map(

                attrgetter("__name__"),

                cache.get_models(

                    cache.get_app("defer_regress"), include_deferred=True

                ),

            )

        )

        self.assertEqual(

            klasses, [

                "Child",

                "Child_Deferred_value",

                "Item",

                "Item_Deferred_name",

                "Item_Deferred_name_other_value_text",

                "Item_Deferred_name_other_value_value",

                "Item_Deferred_other_value_text_value",

                "Item_Deferred_text_value",

                "Leaf",

                "Leaf_Deferred_child_id_second_child_id_value",

                "Leaf_Deferred_name_value",

                "Leaf_Deferred_second_child_value",

                "Leaf_Deferred_value",

                "RelatedItem",

                "RelatedItem_Deferred_",

                "RelatedItem_Deferred_item_id",

                "ResolveThis",

            ]

        )

    def test_resolve_columns(self):

        rt = ResolveThis.objects.create(num=5.0, name='Foobar')

        qs = ResolveThis.objects.defer('num')

        self.assertEqual(1, qs.count())

        self.assertEqual('Foobar', qs[0].name)