django/tests/serializers/test_natural.py

from django.core import serializers
from django.db import connection
from django.test import TestCase

from .models import (
    Child,
    FKAsPKNoNaturalKey,
    FKDataNaturalKey,
    NaturalKeyAnchor,
    NaturalKeyThing,
    NaturalPKWithDefault,
)
from .tests import register_tests


class NaturalKeySerializerTests(TestCase):
    pass


def natural_key_serializer_test(self, format):
    # Create all the objects defined in the test data
    with connection.constraint_checks_disabled():
        objects = [
            NaturalKeyAnchor.objects.create(id=1100, data="Natural Key Anghor"),
            FKDataNaturalKey.objects.create(id=1101, data_id=1100),
            FKDataNaturalKey.objects.create(id=1102, data_id=None),
        ]
    # Serialize the test database
    serialized_data = serializers.serialize(
        format, objects, indent=2, use_natural_foreign_keys=True
    )

    for obj in serializers.deserialize(format, serialized_data):
        obj.save()

    # Assert that the deserialized data is the same
    # as the original source
    for obj in objects:
        instance = obj.__class__.objects.get(id=obj.pk)
        self.assertEqual(
            obj.data,
            instance.data,
            "Objects with PK=%d not equal; expected '%s' (%s), got '%s' (%s)"
            % (
                obj.pk,
                obj.data,
                type(obj.data),
                instance,
                type(instance.data),
            ),
        )


def natural_key_test(self, format):
    book1 = {
        "data": "978-1590597255",
        "title": "The Definitive Guide to Django: Web Development Done Right",
    }
    book2 = {"data": "978-1590599969", "title": "Practical Django Projects"}

    # Create the books.
    adrian = NaturalKeyAnchor.objects.create(**book1)
    james = NaturalKeyAnchor.objects.create(**book2)

    # Serialize the books.
    string_data = serializers.serialize(
        format,
        NaturalKeyAnchor.objects.all(),
        indent=2,
        use_natural_foreign_keys=True,
        use_natural_primary_keys=True,
    )

    # Delete one book (to prove that the natural key generation will only
    # restore the primary keys of books found in the database via the
    # get_natural_key manager method).
    james.delete()

    # Deserialize and test.
    books = list(serializers.deserialize(format, string_data))
    self.assertCountEqual(
        [(book.object.title, book.object.pk) for book in books],
        [
            (book1["title"], adrian.pk),
            (book2["title"], None),
        ],
    )


def natural_pk_mti_test(self, format):
    """
    If serializing objects in a multi-table inheritance relationship using
    natural primary keys, the natural foreign key for the parent is output in
    the fields of the child so it's possible to relate the child to the parent
    when deserializing.
    """
    child_1 = Child.objects.create(parent_data="1", child_data="1")
    child_2 = Child.objects.create(parent_data="2", child_data="2")
    string_data = serializers.serialize(
        format,
        [child_1.parent_ptr, child_2.parent_ptr, child_2, child_1],
        use_natural_foreign_keys=True,
        use_natural_primary_keys=True,
    )
    child_1.delete()
    child_2.delete()
    for obj in serializers.deserialize(format, string_data):
        obj.save()
    children = Child.objects.all()
    self.assertEqual(len(children), 2)
    for child in children:
        # If it's possible to find the superclass from the subclass and it's
        # the correct superclass, it's working.
        self.assertEqual(child.child_data, child.parent_data)


def forward_ref_fk_test(self, format):
    t1 = NaturalKeyThing.objects.create(key="t1")
    t2 = NaturalKeyThing.objects.create(key="t2", other_thing=t1)
    t1.other_thing = t2
    t1.save()
    string_data = serializers.serialize(
        format,
        [t1, t2],
        use_natural_primary_keys=True,
        use_natural_foreign_keys=True,
    )
    NaturalKeyThing.objects.all().delete()
    objs_with_deferred_fields = []
    for obj in serializers.deserialize(
        format, string_data, handle_forward_references=True
    ):
        obj.save()
        if obj.deferred_fields:
            objs_with_deferred_fields.append(obj)
    for obj in objs_with_deferred_fields:
        obj.save_deferred_fields()
    t1 = NaturalKeyThing.objects.get(key="t1")
    t2 = NaturalKeyThing.objects.get(key="t2")
    self.assertEqual(t1.other_thing, t2)
    self.assertEqual(t2.other_thing, t1)


def forward_ref_fk_with_error_test(self, format):
    t1 = NaturalKeyThing.objects.create(key="t1")
    t2 = NaturalKeyThing.objects.create(key="t2", other_thing=t1)
    t1.other_thing = t2
    t1.save()
    string_data = serializers.serialize(
        format,
        [t1],
        use_natural_primary_keys=True,
        use_natural_foreign_keys=True,
    )
    NaturalKeyThing.objects.all().delete()
    objs_with_deferred_fields = []
    for obj in serializers.deserialize(
        format, string_data, handle_forward_references=True
    ):
        obj.save()
        if obj.deferred_fields:
            objs_with_deferred_fields.append(obj)
    obj = objs_with_deferred_fields[0]
    msg = "NaturalKeyThing matching query does not exist"
    with self.assertRaisesMessage(serializers.base.DeserializationError, msg):
        obj.save_deferred_fields()


def forward_ref_m2m_test(self, format):
    t1 = NaturalKeyThing.objects.create(key="t1")
    t2 = NaturalKeyThing.objects.create(key="t2")
    t3 = NaturalKeyThing.objects.create(key="t3")
    t1.other_things.set([t2, t3])
    string_data = serializers.serialize(
        format,
        [t1, t2, t3],
        use_natural_primary_keys=True,
        use_natural_foreign_keys=True,
    )
    NaturalKeyThing.objects.all().delete()
    objs_with_deferred_fields = []
    for obj in serializers.deserialize(
        format, string_data, handle_forward_references=True
    ):
        obj.save()
        if obj.deferred_fields:
            objs_with_deferred_fields.append(obj)
    for obj in objs_with_deferred_fields:
        obj.save_deferred_fields()
    t1 = NaturalKeyThing.objects.get(key="t1")
    t2 = NaturalKeyThing.objects.get(key="t2")
    t3 = NaturalKeyThing.objects.get(key="t3")
    self.assertCountEqual(t1.other_things.all(), [t2, t3])


def forward_ref_m2m_with_error_test(self, format):
    t1 = NaturalKeyThing.objects.create(key="t1")
    t2 = NaturalKeyThing.objects.create(key="t2")
    t3 = NaturalKeyThing.objects.create(key="t3")
    t1.other_things.set([t2, t3])
    t1.save()
    string_data = serializers.serialize(
        format,
        [t1, t2],
        use_natural_primary_keys=True,
        use_natural_foreign_keys=True,
    )
    NaturalKeyThing.objects.all().delete()
    objs_with_deferred_fields = []
    for obj in serializers.deserialize(
        format, string_data, handle_forward_references=True
    ):
        obj.save()
        if obj.deferred_fields:
            objs_with_deferred_fields.append(obj)
    obj = objs_with_deferred_fields[0]
    msg = "NaturalKeyThing matching query does not exist"
    with self.assertRaisesMessage(serializers.base.DeserializationError, msg):
        obj.save_deferred_fields()


def pk_with_default(self, format):
    """
    The deserializer works with natural keys when the primary key has a default
    value.
    """
    obj = NaturalPKWithDefault.objects.create(name="name")
    string_data = serializers.serialize(
        format,
        NaturalPKWithDefault.objects.all(),
        use_natural_foreign_keys=True,
        use_natural_primary_keys=True,
    )
    objs = list(serializers.deserialize(format, string_data))
    self.assertEqual(len(objs), 1)
    self.assertEqual(objs[0].object.pk, obj.pk)


def fk_as_pk_natural_key_not_called(self, format):
    """
    The deserializer doesn't rely on natural keys when a model has a custom
    primary key that is a ForeignKey.
    """
    o1 = NaturalKeyAnchor.objects.create(data="978-1590599969")
    o2 = FKAsPKNoNaturalKey.objects.create(pk_fk=o1)
    serialized_data = serializers.serialize(format, [o1, o2])
    deserialized_objects = list(serializers.deserialize(format, serialized_data))
    self.assertEqual(len(deserialized_objects), 2)
    for obj in deserialized_objects:
        self.assertEqual(obj.object.pk, o1.pk)


# Dynamically register tests for each serializer
register_tests(
    NaturalKeySerializerTests,
    "test_%s_natural_key_serializer",
    natural_key_serializer_test,
)
register_tests(
    NaturalKeySerializerTests, "test_%s_serializer_natural_keys", natural_key_test
)
register_tests(
    NaturalKeySerializerTests, "test_%s_serializer_natural_pks_mti", natural_pk_mti_test
)
register_tests(
    NaturalKeySerializerTests, "test_%s_forward_references_fks", forward_ref_fk_test
)
register_tests(
    NaturalKeySerializerTests,
    "test_%s_forward_references_fk_errors",
    forward_ref_fk_with_error_test,
)
register_tests(
    NaturalKeySerializerTests, "test_%s_forward_references_m2ms", forward_ref_m2m_test
)
register_tests(
    NaturalKeySerializerTests,
    "test_%s_forward_references_m2m_errors",
    forward_ref_m2m_with_error_test,
)
register_tests(NaturalKeySerializerTests, "test_%s_pk_with_default", pk_with_default)
register_tests(
    NaturalKeySerializerTests,
    "test_%s_fk_as_pk_natural_key_not_called",
    fk_as_pk_natural_key_not_called,
)