/tests/modeltests/update/tests.py

from django.test import TestCase

from models import A, B, C, D, DataPoint, RelatedPoint


class SimpleTest(TestCase):
    def setUp(self):
        self.a1 = A.objects.create()
        self.a2 = A.objects.create()
        for x in range(20):
            B.objects.create(a=self.a1)
            D.objects.create(a=self.a1)

    def test_nonempty_update(self):
        """
        Test that update changes the right number of rows for a nonempty queryset
        """
        num_updated = self.a1.b_set.update(y=100)
        self.assertEqual(num_updated, 20)
        cnt = B.objects.filter(y=100).count()
        self.assertEqual(cnt, 20)

    def test_empty_update(self):
        """
        Test that update changes the right number of rows for an empty queryset
        """
        num_updated = self.a2.b_set.update(y=100)
        self.assertEqual(num_updated, 0)
        cnt = B.objects.filter(y=100).count()
        self.assertEqual(cnt, 0)

    def test_nonempty_update_with_inheritance(self):
        """
        Test that update changes the right number of rows for an empty queryset
        when the update affects only a base table
        """
        num_updated = self.a1.d_set.update(y=100)
        self.assertEqual(num_updated, 20)
        cnt = D.objects.filter(y=100).count()
        self.assertEqual(cnt, 20)

    def test_empty_update_with_inheritance(self):
        """
        Test that update changes the right number of rows for an empty queryset
        when the update affects only a base table
        """
        num_updated = self.a2.d_set.update(y=100)
        self.assertEqual(num_updated, 0)
        cnt = D.objects.filter(y=100).count()
        self.assertEqual(cnt, 0)

class AdvancedTests(TestCase):

    def setUp(self):
        self.d0 = DataPoint.objects.create(name="d0", value="apple")
        self.d2 = DataPoint.objects.create(name="d2", value="banana")
        self.d3 = DataPoint.objects.create(name="d3", value="banana")
        self.r1 = RelatedPoint.objects.create(name="r1", data=self.d3)

    def test_update(self):
        """
        Objects are updated by first filtering the candidates into a queryset
        and then calling the update() method. It executes immediately and
        returns nothing.
        """
        resp = DataPoint.objects.filter(value="apple").update(name="d1")
        self.assertEqual(resp, 1)
        resp = DataPoint.objects.filter(value="apple")
        self.assertEqual(list(resp), [self.d0])

    def test_update_multiple_objects(self):
        """
        We can update multiple objects at once.
        """
        resp = DataPoint.objects.filter(value="banana").update(
            value="pineapple")
        self.assertEqual(resp, 2)
        self.assertEqual(DataPoint.objects.get(name="d2").value, u'pineapple')

    def test_update_fk(self):
        """
        Foreign key fields can also be updated, although you can only update
        the object referred to, not anything inside the related object.
        """
        resp = RelatedPoint.objects.filter(name="r1").update(data=self.d0)
        self.assertEqual(resp, 1)
        resp = RelatedPoint.objects.filter(data__name="d0")
        self.assertEqual(list(resp), [self.r1])

    def test_update_multiple_fields(self):
        """
        Multiple fields can be updated at once
        """
        resp = DataPoint.objects.filter(value="apple").update(
            value="fruit", another_value="peach")
        self.assertEqual(resp, 1)
        d = DataPoint.objects.get(name="d0")
        self.assertEqual(d.value, u'fruit')
        self.assertEqual(d.another_value, u'peach')

    def test_update_all(self):
        """
        In the rare case you want to update every instance of a model, update()
        is also a manager method.
        """
        self.assertEqual(DataPoint.objects.update(value='thing'), 3)
        resp = DataPoint.objects.values('value').distinct()
        self.assertEqual(list(resp), [{'value': u'thing'}])

    def test_update_slice_fail(self):
        """
        We do not support update on already sliced query sets.
        """
        method = DataPoint.objects.all()[:2].update
        self.assertRaises(AssertionError, method,
            another_value='another thing')