def context(self):
"""Establish a context for a set of NDB calls.
This method provides a context manager which establishes the runtime
state for using NDB.
For example:
.. code-block:: python
from google.cloud import ndb
client = ndb.Client()
with client.context():
# Use NDB for some stuff
pass
Use of a context is required--NDB can only be used inside a running
context. The context is used to manage the connection to Google Cloud
Datastore, an event loop for asynchronous API calls, runtime caching
policy, and other essential runtime state.
Code within an asynchronous context should be single threaded.
Internally, a :class:`threading.local` instance is used to track the
current event loop.
In a web application, it is recommended that a single context be used
per HTTP request. This can typically be accomplished in a middleware
layer.
"""
return _runstate.state_context(self)
def test_get_event_loop():
with pytest.raises(exceptions.ContextError):
_eventloop.get_event_loop()
with _runstate.state_context(None):
loop = _eventloop.get_event_loop()
assert isinstance(loop, _eventloop.EventLoop)
assert _eventloop.get_event_loop() is loop
def test_insecure_channel(datastore_pb2_grpc, grpc):
channel = grpc.insecure_channel.return_value
client = mock.Mock(
secure=False, host="thehost", spec=("secure", "host")
)
with _runstate.state_context(client):
stub = _api.stub()
assert stub is datastore_pb2_grpc.DatastoreStub.return_value
datastore_pb2_grpc.DatastoreStub.assert_called_once_with(channel)
grpc.insecure_channel.assert_called_once_with("thehost")
def test_state_context():
assert _runstate.states.current() is None
client1 = object()
client2 = object()
with _runstate.state_context(client1):
one = _runstate.current()
assert one.client is client1
with _runstate.state_context(client2):
two = _runstate.current()
assert two.client is client2
assert one is not two
two.eventloop = unittest.mock.Mock(spec=("run", ))
two.eventloop.run.assert_not_called()
assert _runstate.current() is one
two.eventloop.run.assert_called_once_with()
assert _runstate.states.current() is None
def test_secure_channel(datastore_pb2_grpc, _helpers):
channel = _helpers.make_secure_channel.return_value
client = mock.Mock(
_credentials="creds",
secure=True,
host="thehost",
spec=("_credentials", "secure", "host"),
)
with _runstate.state_context(client):
stub = _api.stub()
assert _api.stub() is stub # one stub per context
assert stub is datastore_pb2_grpc.DatastoreStub.return_value
datastore_pb2_grpc.DatastoreStub.assert_called_once_with(channel)
_helpers.make_secure_channel.assert_called_once_with(
"creds", _http.DEFAULT_USER_AGENT, "thehost")
def test_run1(EventLoop):
EventLoop.return_value = loop = unittest.mock.Mock(spec=("run", "run1"))
with _runstate.state_context(None):
_eventloop.run1()
loop.run1.assert_called_once_with()
def test_queue_rpc(EventLoop):
EventLoop.return_value = loop = unittest.mock.Mock(spec=("run",
"queue_rpc"))
with _runstate.state_context(None):
_eventloop.queue_rpc("foo", "bar")
loop.queue_rpc.assert_called_once_with("foo", "bar")
def test_add_idle(EventLoop):
EventLoop.return_value = loop = unittest.mock.Mock(spec=("run",
"add_idle"))
with _runstate.state_context(None):
_eventloop.add_idle("foo", "bar", baz="qux")
loop.add_idle.assert_called_once_with("foo", "bar", baz="qux")
def runstate():
client = None
with _runstate.state_context(client) as state:
yield state
def with_runstate_context():
client = None
with _runstate.state_context(client):
yield
