Sanic Support¶
THIS IS A WIP
Work with Sanic¶
Using the Sanic extension, the request handler acquires a lazy connection on each request, and return the connection when the response finishes by default.
The lazy connection is actually established if necessary, i.e. just before first access to db.
This behavior is controlled by app.config.DB_USE_CONNECTION_FOR_REQUEST, which is True by default.
Supported configurations:
DB_HOST
DB_PORT
DB_USER
DB_PASSWORD
DB_DATABASE
DB_ECHO
DB_POOL_MIN_SIZE
DB_POOL_MAX_SIZE
DB_USE_CONNECTION_FOR_REQUEST
DB_KWARGS
An example server:
from sanic import Sanic
from sanic.exceptions import abort
from sanic.response import json
from gino.ext.sanic import Gino
app = Sanic()
app.config.DB_HOST = 'localhost'
app.config.DB_DATABASE = 'gino'
db = Gino()
db.init_app(app)
class User(db.Model):
__tablename__ = 'users'
id = db.Column(db.BigInteger(), primary_key=True)
nickname = db.Column(db.Unicode())
def __repr__(self):
return '{}<{}>'.format(self.nickname, self.id)
@app.route("/users/<user_id>")
async def get_user(request, user_id):
if not user_id.isdigit():
abort(400, 'invalid user id')
user = await User.get_or_404(int(user_id))
return json({'name': user.nickname})
if __name__ == '__main__':
app.run(debug=True)
Sanic Support¶
To integrate with Sanic, a few configurations needs to be set in
app.config
(with default value though):
DB_HOST: if not set,
localhost
DB_PORT: if not set,
5432
DB_USER: if not set,
postgres
DB_PASSWORD: if not set, empty string
DB_DATABASE: if not set,
postgres
DB_ECHO: if not set,
False
DB_POOL_MIN_SIZE: if not set, 5
DB_POOL_MAX_SIZE: if not set, 10
DB_KWARGS; if not set, empty dictionary
An example:
from sanic import Sanic
from gino.ext.sanic import Gino
app = Sanic()
app.config.DB_HOST = 'localhost'
app.config.DB_USER = 'postgres'
db = Gino()
db.init_app(app)
After db.init_app
, a connection pool with configured settings shall be
created and bound to db
when Sanic server is started, and closed on stop.
Furthermore, a lazy connection context is created on each request, and released
on response. That is to say, within Sanic request handlers, you can directly
access db by e.g. User.get(1)
, everything else is settled: database pool is
created on server start, connection is lazily borrowed from pool on the first
database access and shared within the rest of the same request handler, and
automatically returned to the pool on response.
Please be noted that, in the async world, await
may block unpredictably for
a long time. When this world is crossing RDBMS pools and transactions, it is
a very dangerous bite for performance, even causing disasters sometimes.
Therefore we recommend, during the time enjoying fast development, do pay
special attention to the scope of transactions and borrowed connections, make
sure that transactions are closed as soon as possible, and connections are not
taken for unnecessarily long time. As for the Sanic support, if you want to
release the concrete connection in the request context before response is
reached, just do it like this:
await request['connection'].release()
Or if you prefer not to use the contextual lazy connection in certain handlers,
prefer explicitly manage the connection lifetime, you can always borrow a new
connection by setting reuse=False
:
async with db.acquire(reuse=False):
# new connection context is created
Or if you prefer not to use the builtin request-scoped lazy connection at all, you can simply turn it off:
app.config.DB_USE_CONNECTION_FOR_REQUEST = False