Frequently Asked Questions¶

Are there any plans for @app.route decorator like in Flask?
How to create route that catches urls with given prefix?
Where to put my database connection so handlers can access it?
Why the minimal supported version is Python 3.4.1
How a middleware may store a data for using by web-handler later?

Are there any plans for @app.route decorator like in Flask?¶

There are couple issues here:

This adds huge problem name “configuration as side effect of importing”.
Route matching is order specific, it is very hard to maintain import order.
In semi large application better to have routes table defined in one place.

For this reason feature will not be implemented. But if you really want to use decorators just derive from web.Application and add desired method.

How to create route that catches urls with given prefix?¶

Try something like:

app.router.add_route('*', '/path/to/{tail:.+}', sink_handler)

Where first argument, star, means catch any possible method (GET, POST, OPTIONS, etc), second matching url with desired prefix, third - handler.

Where to put my database connection so handlers can access it?¶

aiohttp.web.Application object supports dict interface, and right place to store your database connections or any other resource you want to share between handlers. Take a look on following example:

async def go(request):
    db = request.app['db']
    cursor = await db.cursor()
    await cursor.execute('SELECT 42')
    # ...
    return web.Response(status=200, text='ok')


async def init_app(loop):
    app = Application(loop=loop)
    db = await crate_connection(user='user', password='123')
    app['db'] = db
    app.router.add_route('GET', '/', go)
    return app

Why the minimal supported version is Python 3.4.1 ¶

As of aiohttp v0.18.0 we dropped support for Python 3.3 up to 3.4.1. The main reason for that is the object.__del__() method, which is fully working since Python 3.4.1 and we need it for proper resource closing.

The last Python 3.3, 3.4.0 compatible version of aiohttp is v0.17.4.

This should not be an issue for most aiohttp users (for example Ubuntu 14.04.3 LTS provides python upgraded to 3.4.3), however libraries depending on aiohttp should consider this and either freeze aiohttp version or drop Python 3.3 support as well.

How a middleware may store a data for using by web-handler later?¶

aiohttp.web.Request supports dict interface as well as aiohttp.web.Application.

Just put data inside request:

async def handler(request):
    requset['unique_key'] = data

See https://github.com/aio-libs/aiohttp_session code for inspiration, aiohttp_session.get_session(request) method uses SESSION_KEY for saving request specific session info.