regression test for bug 7110 when using selectrelated we must query the device and building tables using two different aliases each in order to differentiate the start and end connection fields the net result is that both the connections queries here should give the same results without pulling in more than the absolute minimum number of tables history has shown that it s easy to make a mistake in the implementation and include some unnecessary bonus joins this final query should only have seven tables port device and building twice each plus connection once thus 6 joins plus the from table regression test for bug 8106 same sort of problem as the previous test but this time there are more extra tables to pull in as part of the selectrelated and some of them could potentially clash so need to be kept separate regression test for bug 8036 the first related model in the tests below state is empty and we try to select the more remotely related statecountry the regression here was not skipping the empty column results for country before getting status exercising selectrelated with multitable model inheritance c1 child objects createnamechild1 value42 i1 item objects createnameitem1 childc1 i2 item objects createnameitem2 self assertsequenceequal item objects selectrelatedchild orderbyname i1 i2 def testregression12851self australia country objects createnameaustralia active clientstatus objects createnameactive wa state objects createnamewestern australia countryaustralia client objects createnamebrian burke statewa statusactive burke client objects selectrelatedstate deferstatename getnamebrian burke self assertequalburke name brian burke self assertequalburke state name western australia still works if we re dealing with an inherited class specialclient objects create nametroy buswell statewa statusactive value42 troy specialclient objects selectrelatedstate deferstatename getnametroy buswell self assertequaltroy name troy buswell self assertequaltroy value 42 self assertequaltroy state name western australia still works if we defer an attribute on the inherited class troy specialclient objects selectrelatedstate defervalue statename getnametroy buswell self assertequaltroy name troy buswell self assertequaltroy value 42 self assertequaltroy state name western australia also works if you use only rather than defer troy specialclient objects selectrelatedstate onlyname state getnametroy buswell self assertequaltroy name troy buswell self assertequaltroy value 42 self assertequaltroy state name western australia def testnulljoinpromotionself australia country objects createnameaustralia active clientstatus objects createnameactive wa state objects createnamewestern australia countryaustralia bob client objects createnamebob statusactive jack client objects createnamejack statusactive statewa qs client objects filterstatewa selectrelatedstate with self assertnumqueries1 self assertequallistqs jack self assertequalqs0 state wa the selectrelated join wasn t promoted as there was already an existing even if trimmed inner join to state self assertnotinleft outer strqs query qs client objects selectrelatedstate orderbyname with self assertnumqueries1 self assertequallistqs bob jack self assertisqs0 state none self assertequalqs1 state wa the selectrelated join was promoted as there is already an existing join self assertinleft outer strqs query def testregression19870self hen hen objects createnamehen chick objects createnamechick motherhen self assertequalchick objects all0 mother name hen self assertequalchick objects selectrelated0 mother name hen def testregression10733self a a objects createnamea lotsoftextlotsoftexta afieldafield b b objects createnameb lotsoftextlotsoftextb bfieldbfield c c objects create namec lotsoftextlotsoftextc ispublishedtrue caa cbb results c objects only name lotsoftext ca cb cblotsoftext caname cbname selectrelated self assertsequenceequalresults c with self assertnumqueries0 qsc results0 self assertequalqsc name c self assertequalqsc lotsoftext lotsoftextc self assertequalqsc cb lotsoftext lotsoftextb self assertequalqsc ca name a self assertequalqsc cb name b def testregression22508self building building objects createname101 device device objects createnamerouter buildingbuilding port objects createportnumber1 devicedevice device device objects get port device portset selectrelateddevicebuilding get with self assertnumqueries0 port device building regression test for bug 7110 when using select_related we must query the device and building tables using two different aliases each in order to differentiate the start and end connection fields the net result is that both the connections queries here should give the same results without pulling in more than the absolute minimum number of tables history has shown that it s easy to make a mistake in the implementation and include some unnecessary bonus joins this final query should only have seven tables port device and building twice each plus connection once thus 6 joins plus the from table regression test for bug 8106 same sort of problem as the previous test but this time there are more extra tables to pull in as part of the select_related and some of them could potentially clash so need to be kept separate regression test for bug 8036 the first related model in the tests below state is empty and we try to select the more remotely related state__country the regression here was not skipping the empty column results for country before getting status exercising select_related with multi table model inheritance regression for 12851 deferred fields are used correctly if you select_related a subset of fields still works if we re dealing with an inherited class still works if we defer an attribute on the inherited class also works if you use only rather than defer the select_related join wasn t promoted as there was already an existing even if trimmed inner join to state the select_related join was promoted as there is already an existing join
from django.test import TestCase

from .models import (
    A,
    B,
    Building,
    C,
    Chick,
    Child,
    Class,
    Client,
    ClientStatus,
    Connection,
    Country,
    Device,
    Enrollment,
    Hen,
    Item,
    Organizer,
    Person,
    Port,
    SpecialClient,
    State,
    Student,
    TUser,
)


class SelectRelatedRegressTests(TestCase):
    def test_regression_7110(self):
        

        b = Building.objects.create(name="101")
        dev1 = Device.objects.create(name="router", building=b)
        dev2 = Device.objects.create(name="switch", building=b)
        dev3 = Device.objects.create(name="server", building=b)
        port1 = Port.objects.create(port_number="4", device=dev1)
        port2 = Port.objects.create(port_number="7", device=dev2)
        port3 = Port.objects.create(port_number="1", device=dev3)
        c1 = Connection.objects.create(start=port1, end=port2)
        c2 = Connection.objects.create(start=port2, end=port3)

        connections = Connection.objects.filter(
            start__device__building=b, end__device__building=b
        ).order_by("id")
        self.assertEqual(
            [(c.id, str(c.start), str(c.end)) for c in connections],
            [(c1.id, "router/4", "switch/7"), (c2.id, "switch/7", "server/1")],
        )

        connections = (
            Connection.objects.filter(
                start__device__building=b, end__device__building=b
            )
            .select_related()
            .order_by("id")
        )
        self.assertEqual(
            [(c.id, str(c.start), str(c.end)) for c in connections],
            [(c1.id, "router/4", "switch/7"), (c2.id, "switch/7", "server/1")],
        )

        
        
        self.assertEqual(str(connections.query).count(" JOIN "), 6)

    def test_regression_8106(self):
        

        us = TUser.objects.create(name="std")
        usp = Person.objects.create(user=us)
        uo = TUser.objects.create(name="org")
        uop = Person.objects.create(user=uo)
        s = Student.objects.create(person=usp)
        o = Organizer.objects.create(person=uop)
        c = Class.objects.create(org=o)
        Enrollment.objects.create(std=s, cls=c)

        e_related = Enrollment.objects.select_related()[0]
        self.assertEqual(e_related.std.person.user.name, "std")
        self.assertEqual(e_related.cls.org.person.user.name, "org")

    def test_regression_8036(self):
        

        Country.objects.create(name="Australia")
        active = ClientStatus.objects.create(name="active")
        client = Client.objects.create(name="client", status=active)

        self.assertEqual(client.status, active)
        self.assertEqual(Client.objects.select_related()[0].status, active)
        self.assertEqual(Client.objects.select_related("state")[0].status, active)
        self.assertEqual(
            Client.objects.select_related("state", "status")[0].status, active
        )
        self.assertEqual(
            Client.objects.select_related("state__country")[0].status, active
        )
        self.assertEqual(
            Client.objects.select_related("state__country", "status")[0].status, active
        )
        self.assertEqual(Client.objects.select_related("status")[0].status, active)

    def test_multi_table_inheritance(self):
        
        c1 = Child.objects.create(name="child1", value=42)
        i1 = Item.objects.create(name="item1", child=c1)
        i2 = Item.objects.create(name="item2")

        self.assertSequenceEqual(
            Item.objects.select_related("child").order_by("name"),
            [i1, i2],
        )

    def test_regression_12851(self):
        
        australia = Country.objects.create(name="Australia")
        active = ClientStatus.objects.create(name="active")

        wa = State.objects.create(name="Western Australia", country=australia)
        Client.objects.create(name="Brian Burke", state=wa, status=active)
        burke = (
            Client.objects.select_related("state")
            .defer("state__name")
            .get(name="Brian Burke")
        )

        self.assertEqual(burke.name, "Brian Burke")
        self.assertEqual(burke.state.name, "Western Australia")

        
        SpecialClient.objects.create(
            name="Troy Buswell", state=wa, status=active, value=42
        )
        troy = (
            SpecialClient.objects.select_related("state")
            .defer("state__name")
            .get(name="Troy Buswell")
        )

        self.assertEqual(troy.name, "Troy Buswell")
        self.assertEqual(troy.value, 42)
        self.assertEqual(troy.state.name, "Western Australia")

        
        troy = (
            SpecialClient.objects.select_related("state")
            .defer("value", "state__name")
            .get(name="Troy Buswell")
        )

        self.assertEqual(troy.name, "Troy Buswell")
        self.assertEqual(troy.value, 42)
        self.assertEqual(troy.state.name, "Western Australia")

        
        troy = (
            SpecialClient.objects.select_related("state")
            .only("name", "state")
            .get(name="Troy Buswell")
        )

        self.assertEqual(troy.name, "Troy Buswell")
        self.assertEqual(troy.value, 42)
        self.assertEqual(troy.state.name, "Western Australia")

    def test_null_join_promotion(self):
        australia = Country.objects.create(name="Australia")
        active = ClientStatus.objects.create(name="active")

        wa = State.objects.create(name="Western Australia", country=australia)
        bob = Client.objects.create(name="Bob", status=active)
        jack = Client.objects.create(name="Jack", status=active, state=wa)
        qs = Client.objects.filter(state=wa).select_related("state")
        with self.assertNumQueries(1):
            self.assertEqual(list(qs), [jack])
            self.assertEqual(qs[0].state, wa)
            
            
            self.assertNotIn("LEFT OUTER", str(qs.query))
        qs = Client.objects.select_related("state").order_by("name")
        with self.assertNumQueries(1):
            self.assertEqual(list(qs), [bob, jack])
            self.assertIs(qs[0].state, None)
            self.assertEqual(qs[1].state, wa)
            
            
            self.assertIn("LEFT OUTER", str(qs.query))

    def test_regression_19870(self):
        hen = Hen.objects.create(name="Hen")
        Chick.objects.create(name="Chick", mother=hen)

        self.assertEqual(Chick.objects.all()[0].mother.name, "Hen")
        self.assertEqual(Chick.objects.select_related()[0].mother.name, "Hen")

    def test_regression_10733(self):
        a = A.objects.create(name="a", lots_of_text="lots_of_text_a", a_field="a_field")
        b = B.objects.create(name="b", lots_of_text="lots_of_text_b", b_field="b_field")
        c = C.objects.create(
            name="c", lots_of_text="lots_of_text_c", is_published=True, c_a=a, c_b=b
        )
        results = C.objects.only(
            "name",
            "lots_of_text",
            "c_a",
            "c_b",
            "c_b__lots_of_text",
            "c_a__name",
            "c_b__name",
        ).select_related()
        self.assertSequenceEqual(results, [c])
        with self.assertNumQueries(0):
            qs_c = results[0]
            self.assertEqual(qs_c.name, "c")
            self.assertEqual(qs_c.lots_of_text, "lots_of_text_c")
            self.assertEqual(qs_c.c_b.lots_of_text, "lots_of_text_b")
            self.assertEqual(qs_c.c_a.name, "a")
            self.assertEqual(qs_c.c_b.name, "b")

    def test_regression_22508(self):
        building = Building.objects.create(name="101")
        device = Device.objects.create(name="router", building=building)
        Port.objects.create(port_number="1", device=device)

        device = Device.objects.get()
        port = device.port_set.select_related("device__building").get()
        with self.assertNumQueries(0):
            port.device.building