6979265fa6
This allows for async functions to be passed to the Flask class
instance, for example as a view function,
@app.route("/")
async def index():
return "Async hello"
this comes with a cost though of poorer performance than using the
sync equivalent.
asgiref is the standard way to run async code within a sync context,
and is used in Django making it a safe and sane choice for this.
46 lines
1.2 KiB
ReStructuredText
46 lines
1.2 KiB
ReStructuredText
.. _async_await:
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Using async and await
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=====================
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.. versionadded:: 2.0
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Routes, error handlers, before request, after request, and teardown
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functions can all be coroutine functions if Flask is installed with
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the ``async`` extra (``pip install flask[async]``). This allows code
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such as,
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.. code-block:: python
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@app.route("/")
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async def index():
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return await ...
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including the usage of any asyncio based libraries.
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When to use Quart instead
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-------------------------
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Flask's ``async/await`` support is less performant than async first
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frameworks due to the way it is implemented. Therefore if you have a
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mainly async codebase it would make sense to consider `Quart
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<https://gitlab.com/pgjones/quart>`_. Quart is a reimplementation of
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the Flask using ``async/await`` based on the ASGI standard (Flask is
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based on the WSGI standard).
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Decorators
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----------
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Decorators designed for Flask, such as those in Flask extensions are
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unlikely to work. This is because the decorator will not await the
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coroutine function nor will they themselves be awaitable.
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Other event loops
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-----------------
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At the moment Flask only supports asyncio - the
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:meth:`flask.Flask.ensure_sync` should be overridden to support
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alternative event loops.
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