from operator import attrgetter from django.test import TestCase from models import Question, Answer class OrderWithRespectToTests(TestCase): def test_basic(self): q1 = Question.objects.create(text="Which Beatle starts with the letter 'R'?") q2 = Question.objects.create(text="What is your name?") Answer.objects.create(text="John", question=q1) Answer.objects.create(text="Jonno", question=q2) Answer.objects.create(text="Paul", question=q1) Answer.objects.create(text="Paulo", question=q2) Answer.objects.create(text="George", question=q1) Answer.objects.create(text="Ringo", question=q1) # The answers will always be ordered in the order they were inserted. self.assertQuerysetEqual( q1.answer_set.all(), [ "John", "Paul", "George", "Ringo", ], attrgetter("text"), ) # We can retrieve the answers related to a particular object, in the # order they were created, once we have a particular object. a1 = Answer.objects.filter(question=q1)[0] self.assertEqual(a1.text, "John") a2 = a1.get_next_in_order() self.assertEqual(a2.text, "Paul") a4 = list(Answer.objects.filter(question=q1))[-1] self.assertEqual(a4.text, "Ringo") self.assertEqual(a4.get_previous_in_order().text, "George") # Determining (and setting) the ordering for a particular item is also # possible. id_list = [o.pk for o in q1.answer_set.all()] self.assertEqual(a2.question.get_answer_order(), id_list) a5 = Answer.objects.create(text="Number five", question=q1) # It doesn't matter which answer we use to check the order, it will # always be the same. self.assertEqual( a2.question.get_answer_order(), a5.question.get_answer_order() ) # The ordering can be altered: id_list = [o.pk for o in q1.answer_set.all()] x = id_list.pop() id_list.insert(-1, x) self.assertNotEqual(a5.question.get_answer_order(), id_list) a5.question.set_answer_order(id_list) self.assertQuerysetEqual( q1.answer_set.all(), [ "John", "Paul", "George", "Number five", "Ringo" ], attrgetter("text") )