from django.db import models class Building(models.Model): name = models.CharField(max_length=10) def __unicode__(self): return u"Building: %s" % self.name class Device(models.Model): building = models.ForeignKey('Building') name = models.CharField(max_length=10) def __unicode__(self): return u"device '%s' in building %s" % (self.name, self.building) class Port(models.Model): device = models.ForeignKey('Device') port_number = models.CharField(max_length=10) def __unicode__(self): return u"%s/%s" % (self.device.name, self.port_number) class Connection(models.Model): start = models.ForeignKey(Port, related_name='connection_start', unique=True) end = models.ForeignKey(Port, related_name='connection_end', unique=True) def __unicode__(self): return u"%s to %s" % (self.start, self.end) # Another non-tree hierarchy that exercises code paths similar to the above # example, but in a slightly different configuration. class TUser(models.Model): name = models.CharField(max_length=200) class Person(models.Model): user = models.ForeignKey(TUser, unique=True) class Organizer(models.Model): person = models.ForeignKey(Person) class Student(models.Model): person = models.ForeignKey(Person) class Class(models.Model): org = models.ForeignKey(Organizer) class Enrollment(models.Model): std = models.ForeignKey(Student) cls = models.ForeignKey(Class) # Models for testing bug #8036. class Country(models.Model): name = models.CharField(max_length=50) class State(models.Model): name = models.CharField(max_length=50) country = models.ForeignKey(Country) class ClientStatus(models.Model): name = models.CharField(max_length=50) class Client(models.Model): name = models.CharField(max_length=50) state = models.ForeignKey(State, null=True) status = models.ForeignKey(ClientStatus) __test__ = {'API_TESTS': """ 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). >>> 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') >>> [(c.id, unicode(c.start), unicode(c.end)) for c in connections] [(1, u'router/4', u'switch/7'), (2, u'switch/7', u'server/1')] >>> connections=Connection.objects.filter(start__device__building=b, end__device__building=b).select_related().order_by('id') >>> [(c.id, unicode(c.start), unicode(c.end)) for c in connections] [(1, u'router/4', u'switch/7'), (2, u'switch/7', u'server/1')] # This final query should only join seven tables (port, device and building # twice each, plus connection once). >>> connections.query.count_active_tables() 7 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). >>> 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) >>> e = Enrollment.objects.create(std=s, cls=c) >>> e_related = Enrollment.objects.all().select_related()[0] >>> e_related.std.person.user.name u"std" >>> e_related.cls.org.person.user.name u"org" 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. >>> australia = Country.objects.create(name='Australia') >>> active = ClientStatus.objects.create(name='active') >>> client = Client.objects.create(name='client', status=active) >>> client.status >>> Client.objects.select_related()[0].status >>> Client.objects.select_related('state')[0].status >>> Client.objects.select_related('state', 'status')[0].status >>> Client.objects.select_related('state__country')[0].status >>> Client.objects.select_related('state__country', 'status')[0].status >>> Client.objects.select_related('status')[0].status """}