Django 3.1 async view is done (=> async phase 2 is done !) ¶

See also

History ¶

Phase 1 : Django 3.0 ¶

See also

ASGI (django/core/asgi.py, core/handlers/asgi.py)

Django 3.1 announce ¶

See also

To get started with async views , you need to declare a view using async def :

Example 1 ¶

            # https://docs.python.org/3/library/asyncio.html
# https://docs.python.org/3/library/asyncio-api-index.html
import asyncio

async def my_view(request):
    await asyncio.sleep(0.5)
    return HttpResponse('Hello, async world!')

           

Example 2 ¶

models.py ¶

              # https://docs.python.org/3/library/asyncio-task.html
 import asyncio
 # https://docs.djangoproject.com/en/3.1/topics/async/#async-to-sync
 from asgiref.sync import sync_to_async
 def sync_update_conges():
     print("Begin sync_update_conges()")
     PROJETS_CONGES = Projet.objects.filter(designation__icontains="abs")
     PROJETS_CONGES_ID = [p.id for p in PROJETS_CONGES]


 loop = asyncio.get_event_loop()
 async_function = sync_to_async(sync_update_conges)
 loop.create_task(async_function())

            

Example 3 async Django ¶

urls.py ¶

              path("asyncview/test1", views_asgi.async_view_test_1, name="asgi_async_view_test1"),
 path("syncview/test1", views_asgi.sync_view_test_1, name="asgi_sync_view_test1"),
 path(
     "asyncview/smoke_some_meats",
     views_asgi.smoke_some_meats,
     name="asgi_async_smoke_some_meats",
 ),
 path(
     "asyncview/async_hello", views_asgi.async_hello, name="asgi_async_async_hello"
 ),

            

views_asgi.py ¶

              # https://docs.python.org/3/library/asyncio-task.html
 import asyncio
 # https://docs.djangoproject.com/en/3.1/topics/async/#async-to-sync
 from asgiref.sync import sync_to_async

 def orm_get_fiches_temps_en_calcul() -> None:
     """Incrément du temps passé pour les FICHE_EN_CALCUL."""
     now = datetime.now()
     logger.info(
         f"Begin task_update_fiches_temps_en_calcul() {now.hour:02}H{now.minute:02}mn{now.second:02}s"
     )
     liste_fiches_en_calcul = None
     try:
         liste_fiches_en_calcul = FicheTemps.objects.filter(
             etat=FICHE_STATUS["FICHE_EN_CALCUL"]
         )
         if liste_fiches_en_calcul.count() == 0:
             now = datetime.now()
             logger.info(
                 f"pas de fiches en calcul {now.hour:02}H{now.minute:02}mn{now.second:02}s"
             )
         else:
             # parcours des fiches de temps en calcul
             for fiches_temps in liste_fiches_en_calcul:
                 try:
                     fiches_temps.temps_impute = fiches_temps.temps_impute + timedelta(
                         seconds=INCREMENT_TIME_SECONDS
                     )
                     logger.info(f"Temps impute:{fiches_temps.temps_impute}")
                     fiches_temps.save()
                 except:
                     logger.error("task_update_fiches_temps_en_calcul()")

     except Exception as error:
         logger.error(f"Pb in task_update_fiches_temps_en_calcul = {error=}")

     return liste_fiches_en_calcul


 async def _async_hello():
     while True:
         loop = asyncio.get_event_loop()
         async_function = sync_to_async(orm_get_fiches_temps_en_calcul)
         loop.create_task(async_function())
         await asyncio.sleep(5)


 async def async_hello(request: HttpRequest) -> HttpResponse:
     """Tâche périodique asynchrone.

     http://localhost:8004/fiches_temps/asyncview/async_hello
     """
     loop = asyncio.get_event_loop()
     loop.create_task(_async_hello())
     return HttpResponse(f"Non blocking hello")

            

All asynchronous features are supported whether you are running under WSGI or ASGI mode .

However, there will be performance penalties using async code in WSGI mode .

You can read more about the specifics in Asynchronous support documentation .

You are free to mix async and sync views, middleware, and tests as much as you want. Django will ensure that you always end up with the right execution context.

We expect most projects will keep the majority of their views synchronous, and only have a select few running in async mode but it is entirely your choice .

Django’s ORM, cache layer, and other pieces of code that do long-running network calls do not yet support async access .

We expect to add support for them in upcoming releases .

Async views are ideal, however, if you are doing a lot of API or HTTP calls inside your view, you can now natively do all those HTTP calls in parallel to considerably speed up your view’s execution.

Asynchronous support should be entirely backwards-compatible and we have tried to ensure that it has no speed regressions for your existing, synchronous code.

It should have no noticeable effect on any existing Django projects.

https://github.com/django/django/commit/fc0fa72ff4cdbf5861a366e31cb8bbacd44da22d

Simon Willison ¶

See also

           Node is a tempting option for anything involving comet, file uploads or
even just mashing together potentially slow loading web APIs.

10.5 years later, I'm excited about async views in Django 3.1 for exactly
the same reasons (except we don't call live updates "comet" any more)

Django 3.1 async view is done (=> async phase 2 is done !) ¶

History ¶

Phase 1 : Django 3.0 ¶

Phase 2 : Django 3.1 ¶

Django 3.1 announce ¶

Example 1 ¶

Example 2 ¶

models.py ¶

Example 3 async Django ¶

urls.py ¶

views_asgi.py ¶

Mariusz Felisiak ¶

Andrew Godwin ¶

The fc0fa72ff4cdb git commit ¶

Simon Willison ¶

Tutorials ¶