from __future__ import unicode_literals from django.test import TestCase from .models import Domain, Kingdom, Phylum, Klass, Order, Family, Genus, Species, HybridSpecies class SelectRelatedTests(TestCase): @classmethod def create_tree(cls, stringtree): """ Helper to create a complete tree. """ names = stringtree.split() models = [Domain, Kingdom, Phylum, Klass, Order, Family, Genus, Species] assert len(names) == len(models), (names, models) parent = None for name, model in zip(names, models): try: obj = model.objects.get(name=name) except model.DoesNotExist: obj = model(name=name) if parent: setattr(obj, parent.__class__.__name__.lower(), parent) obj.save() parent = obj @classmethod def setUpTestData(cls): cls.create_tree("Eukaryota Animalia Anthropoda Insecta Diptera Drosophilidae Drosophila melanogaster") cls.create_tree("Eukaryota Animalia Chordata Mammalia Primates Hominidae Homo sapiens") cls.create_tree("Eukaryota Plantae Magnoliophyta Magnoliopsida Fabales Fabaceae Pisum sativum") cls.create_tree("Eukaryota Fungi Basidiomycota Homobasidiomycatae Agaricales Amanitacae Amanita muscaria") def test_access_fks_without_select_related(self): """ Normally, accessing FKs doesn't fill in related objects """ with self.assertNumQueries(8): fly = Species.objects.get(name="melanogaster") domain = fly.genus.family.order.klass.phylum.kingdom.domain self.assertEqual(domain.name, 'Eukaryota') def test_access_fks_with_select_related(self): """ A select_related() call will fill in those related objects without any extra queries """ with self.assertNumQueries(1): person = Species.objects.select_related('genus__family__order__klass__phylum__kingdom__domain').get(name="sapiens") domain = person.genus.family.order.klass.phylum.kingdom.domain self.assertEqual(domain.name, 'Eukaryota') def test_list_without_select_related(self): """ select_related() also of course applies to entire lists, not just items. This test verifies the expected behavior without select_related. """ with self.assertNumQueries(9): world = Species.objects.all() families = [o.genus.family.name for o in world] self.assertEqual(sorted(families), [ 'Amanitacae', 'Drosophilidae', 'Fabaceae', 'Hominidae', ]) def test_list_with_select_related(self): """ select_related() also of course applies to entire lists, not just items. This test verifies the expected behavior with select_related. """ with self.assertNumQueries(1): world = Species.objects.all().select_related() families = [o.genus.family.name for o in world] self.assertEqual(sorted(families), [ 'Amanitacae', 'Drosophilidae', 'Fabaceae', 'Hominidae', ]) def test_list_with_depth(self): """ Passing a relationship field lookup specifier to select_related() will stop the descent at a particular level. This can be used on lists as well. """ with self.assertNumQueries(5): world = Species.objects.all().select_related('genus__family') orders = [o.genus.family.order.name for o in world] self.assertEqual(sorted(orders), ['Agaricales', 'Diptera', 'Fabales', 'Primates']) def test_select_related_with_extra(self): s = (Species.objects.all() .select_related() .extra(select={'a': 'select_related_species.id + 10'})[0]) self.assertEqual(s.id + 10, s.a) def test_certain_fields(self): """ The optional fields passed to select_related() control which related models we pull in. This allows for smaller queries. In this case, we explicitly say to select the 'genus' and 'genus.family' models, leading to the same number of queries as before. """ with self.assertNumQueries(1): world = Species.objects.select_related('genus__family') families = [o.genus.family.name for o in world] self.assertEqual(sorted(families), ['Amanitacae', 'Drosophilidae', 'Fabaceae', 'Hominidae']) def test_more_certain_fields(self): """ In this case, we explicitly say to select the 'genus' and 'genus.family' models, leading to the same number of queries as before. """ with self.assertNumQueries(2): world = Species.objects.filter(genus__name='Amanita')\ .select_related('genus__family') orders = [o.genus.family.order.name for o in world] self.assertEqual(orders, ['Agaricales']) def test_field_traversal(self): with self.assertNumQueries(1): s = (Species.objects.all() .select_related('genus__family__order') .order_by('id')[0:1].get().genus.family.order.name) self.assertEqual(s, 'Diptera') def test_depth_fields_fails(self): self.assertRaises( TypeError, Species.objects.select_related, 'genus__family__order', depth=4 ) def test_none_clears_list(self): queryset = Species.objects.select_related('genus').select_related(None) self.assertEqual(queryset.query.select_related, False) def test_chaining(self): parent_1, parent_2 = Species.objects.all()[:2] HybridSpecies.objects.create(name='hybrid', parent_1=parent_1, parent_2=parent_2) queryset = HybridSpecies.objects.select_related('parent_1').select_related('parent_2') with self.assertNumQueries(1): obj = queryset[0] self.assertEqual(obj.parent_1, parent_1) self.assertEqual(obj.parent_2, parent_2)