Question

我有一个带有实例属性的简单NDB模型，它不是NDB property。我想测试在从数据存储区保存和检索实体时属性值是否丢失。

现在，当检索实体时，它与放入数据存储区的实例相同。

有没有办法以编程方式清除/无效 memcache和 NDB内存缓存？

示例是pytest测试，对不起。

from google.appengine.ext import testbed, ndb


class User(ndb.Model):
    name = ndb.TextProperty()
    foo = None


class TestNDBModel(object):

    def setup(self):
        self.testbed = testbed.Testbed()
        self.testbed.activate()
        self.testbed.init_datastore_v3_stub()
        self.testbed.init_memcache_stub()

    def teardown(self):
        self.testbed.deactivate()

    def test_foo(self):
        user = User(name='Andy')
        assert user.name == 'Andy'
        assert user.foo is None
        user.foo = 123
        assert user.foo == 123
        user_key = user.put()

        # Here I need to clear the cache somehow,
        # so that the entity must be retrieved from datastore

        retrieved_user = user_key.get()

        # These two will now fail
        assert retrieved_user is not user
        assert retrieved_user.foo is None

Answer 1

您显然使用错误的方法为retrieved_user分配值。请改用以下内容：

retrieved_user = user_key.delete(use_datastore=False)

有关详细信息，请参阅以下链接：

https://developers.google.com/appengine/docs/python/ndb/functions#context_options

Answer 2

解决方案是防止实体在使用entity.put(use_cache=False, use_memcache=False)放入数据库时进行缓存。

from google.appengine.ext import testbed, ndb


class User(ndb.Model):
    name = ndb.TextProperty()
    foo = None


class TestNDBModel(object):

    def setup(self):
        self.testbed = testbed.Testbed()
        self.testbed.activate()
        self.testbed.init_datastore_v3_stub()
        self.testbed.init_memcache_stub()

    def teardown(self):
        self.testbed.deactivate()

    def test_foo(self):
        user = User(name='Andy')
        assert user.name == 'Andy'
        assert user.foo is None
        user.foo = 123
        assert user.foo == 123

        # This prevents the entity to be cached
        user_key = user.put(use_cache=False, use_memcache=False)

        # The entity is now retrieved from DB
        retrieved_user = user_key.get()

        # These two will now pass
        assert retrieved_user is not user
        assert retrieved_user.foo is None

Answer 3

我遇到了同样的问题，正在寻找解决方案。这就是诀窍：

ndb.get_context().clear_cache()

如何在测试中清除/无效NDB缓存

3 个答案: