What are the best practices for using async middleware in Django?

What are the best practices for using async middleware in Django?

When using async middleware in Django, it's important to ensure that your middleware is designed to handle asynchronous requests properly. Here are some best practices:

1. Use async/await syntax to avoid blocking the event loop.
2. Ensure that your middleware is compatible with Django's async views.
3. Keep middleware lightweight to minimize performance overhead.
4. Test your middleware thoroughly in an async context.

Can you give an example of async middleware?

Sure! Here's a simple example of async middleware that logs the request time:

import time
from django.utils.deprecation import MiddlewareMixin

class AsyncLoggingMiddleware(MiddlewareMixin):
    async def __call__(self, request):
        start_time = time.time()
        response = await super().__call__(request)
        duration = time.time() - start_time
        print(f'Request took {duration} seconds')
        return response

What should I avoid when writing async middleware?

You should avoid using synchronous code that can block the event loop, such as database queries or long-running computations. Instead, use async-compatible libraries and functions to ensure your middleware remains performant.

How do I test async middleware?

To test async middleware, you can use Django's test client with async support. Use pytest or asgiref to run your tests in an async context, ensuring that you properly await the middleware's execution.