Django Asynchronous Support with Coding Samples

Published Sep 17, 2023

Hello Coders!

This article provides a short introduction to Async Support in Django, a feature that usually improves the user experience and responsiveness in the UI. In order to make the article more useful, a few coding samples are also provided. Thanks for reading!

Django introduced asynchronous (async) support starting from Django 3.0. This feature allows developers to write asynchronous code within Django applications, taking advantage of Python's async and await syntax.

Async support in Django can be beneficial for improving the scalability and responsiveness of web applications, particularly in situations where there are I/O-bound operations, such as database queries or external API calls.

✅ Theoretical Overview

Here's a theoretical overview of how async support works in Django and a few code examples to illustrate its usage.

Async View Functions

With async support, you can define view functions as asynchronous by using the async def syntax.
This allows these functions to perform non-blocking I/O operations and handle multiple requests concurrently.

Database Queries

You can use Django's ORM (Object-Relational Mapping) to perform asynchronous database queries.
Async database queries help avoid blocking the event loop and allow other tasks to run while waiting for the database response.

Middleware

Django provides async middleware support. Middleware components can also be asynchronous, making it possible to perform async operations during request and response processing.

Third-party Libraries

You can use third-party libraries that support async operations, such as HTTP clients for making async requests to external APIs or services.

✅ Code Examples

Here are a few code examples to demonstrate how async support works in Django:

Async View Function

# views.py
from django.http import JsonResponse

async def async_example(request):
    # Simulate an asynchronous task (e.g., fetching data from an API)
    result = await some_async_function()
    return JsonResponse({'result': result})

In this example, the async_example view function is defined as asynchronous using async def. It awaits the result of an asynchronous task, such as fetching data from an external API.

Async Database Query

# views.py
from django.http import JsonResponse
from .models import MyModel

async def async_db_query(request):
    # Perform an asynchronous database query
    queryset = MyModel.objects.filter(some_field=some_value)
    results = await queryset.values()
    return JsonResponse({'results': results})

In this example, an asynchronous database query is performed using Django's ORM. The await keyword is used to wait for the database query to complete without blocking the event loop.

Async Middleware

# middleware.py
class AsyncMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    async def __call__(self, request):
        # Perform an async operation before handling the request
        await some_async_task()
        
        response = await self.get_response(request)
        
        # Perform an async operation after handling the request
        await some_other_async_task()
        
        return response

In this example, the middleware AsyncMiddleware contains asynchronous code that runs before and after the request is handled.
This allows you to perform async tasks at different stages of request processing.

✅ In Summary

Please note that when using async features in Django, the web server needs to support asynchronous code.
For this use case, some popular choices are ASGI (Asynchronous Server Gateway Interface) servers like Daphne or Uvicorn.