Startup and Shutdown¶
The ASGI lifespan specification includes the ability for awaiting
coroutines before the first byte is received and after the final byte
is sent, through the startup
and shutdown
lifespan events.
This is particularly useful for creating and destroying connection
pools. Quart supports this via the decorators
before_serving()
and
after_serving()
, which function like
before_first_request()
.
The decorated functions are all called within the app context,
allowing current_app
and g
to be used.
To use this functionality simply do the following:
@app.before_serving
async def create_db_pool():
app.db_pool = await ...
g.something = something
@app.before_serving
async def use_g():
g.something.do_something()
@app.route("/")
async def index():
app.db_pool.execute(...)
g.something.do_something_else()
@app.after_serving
async def create_db_pool():
await app.db_pool.close()
Testing¶
Quart’s test client works on a request lifespan and hence does not
call before_serving
or after_serving
functions. Instead
Quart’s test app can be used, for example
@pytest.fixture(name="app", scope="function")
async def _app():
app = create_app() # Initialize app
async with app.test_app() as test_app:
yield test_app
The app fixture can then be used as normal, knowing that the
before_serving
and after_serving
functions have been called,
@pytest.mark.asyncio
async def test_index(app):
test_client = app.test_client()
await test_client.get("/")
...