django-browser-reload 1.21.0

Requirements

Python 3.9 to 3.14 supported.

Django 4.2 to 6.0 supported.

Both WSGI and ASGI are supported.

Your browser needs to support:

• EventSource - universally available.

• SharedWorker - available on Chrome, Edge, Firefox, and Opera for a long time. Available on Safari since version 16 (2022-09-12).

Installation

1. Install with pip:

   python -m pip install django-browser-reload

2. Ensure you have "django.contrib.staticfiles" in your INSTALLED_APPS.

3. Add django-browser-reload to your INSTALLED_APPS:

   INSTALLED_APPS = [
       ...,
       "django_browser_reload",
       ...,
   ]

4. Include the app URLs in your root URLconf:

   from django.urls import include, path
   
   urlpatterns = [
       ...,
       path("__reload__/", include("django_browser_reload.urls")),
   ]

   You can use another prefix if required.

5. Add the middleware:

   MIDDLEWARE = [
       # ...
       "django_browser_reload.middleware.BrowserReloadMiddleware",
       # ...
   ]

   The middleware should be listed after any others that encode the response, such as Django’s GZipMiddleware.

   The middleware automatically inserts the required script tag on HTML responses before </body> when DEBUG is True. It does so to every HTML response, meaning it will be included on Django’s debug pages, admin pages, etc. If you want more control, you can instead insert the script tag in your templates—see below.

All done! 📯

Try installing django-watchfiles as well, for faster and more efficient reloading.

Usage

Once set up as above, just run runserver with the DEBUG setting set to True, and open your site in a browser. When you modify Python code, templates, or static assets, the page will automatically reload. Welcome to much faster iteration times!

If you open multiple tabs, only the most recently used tab will reload.

django-browser works by adding a script tag into HTML responses, just before </body>. This script connects back to the development server and receives events that tell it when to reload. These events are triggered through server restarts and runserver’s autoreload system. See below for a more detailed explanation, under “How It Works”.

On Django 6.0+ with ContentSecurityPolicyMiddleware, the <script> tag will include the Content Security Policy (CSP) nonce.

Template tag

You can also use a template tag to insert the script on relevant pages, instead of using the middleware. This may be useful if you want to restrict reloading to certain pages, or if the middleware doesn’t work for your page structure. The template tag has both Django templates and Jinja versions, and only outputs the script tag when DEBUG is True.

For Django Templates, load the tag and use it in your base template. The tag can go anywhere, but it’s best just before </body>:

{% load django_browser_reload %}

...

    {% django_browser_reload_script %}
  </body>
</html>

On Django 6.0+, the <script> tag will include the Content Security Policy (CSP) nonce, if it’s present in the context.

To add the template tag within Django’s admin, do so in a template called admin/base_site.html, per Django’s documentation on extending an overridden template. The template should look like:

{% extends "admin/base_site.html" %}

{% load django_browser_reload %}

{% block extrahead %}
    {{ block.super }}
    {% django_browser_reload_script %}
{% endblock %}

For Jinja Templates, you need to perform two steps. First, load the tag function into the globals of your custom environment:

# myproject/jinja2.py
from jinja2 import Environment
from django_browser_reload.jinja import django_browser_reload_script


def environment(**options):
    env = Environment(**options)
    env.globals.update(
        {
            # ...
            "django_browser_reload_script": django_browser_reload_script,
        }
    )
    return env

Second, render the tag in your base template. It can go anywhere, but it’s best just before </body>:

...
    {{ django_browser_reload_script() }}
  </body>
</html>

To use a CSP nonce, pass it to the function as nonce:

{{ django_browser_reload_script(nonce=csp_nonce) }}

Example project

To demonstrate and test django-browser-reload on all kinds of assets, there is an example project included in the repository. Open the example/ directory, follow the instructions in its README, and try it out.

How it works

Here’s a diagram:

                                     Browser

                             Tab 1    Tab 2     Tab N
                           listener  listener  listener
                                \       |       /
  Django                         \      |      /
                                  \     |     /
Events View --------------------> Shared worker

The middleware (or template tag) includes a listener script on each page. This listener script starts or connects to a SharedWorker, running a worker script. The worker script then connects to the events view in Django, using an EventSource to receive server-sent events.

This event source uses StreamingHttpResponse to send events to the worker. The view continues streaming events indefinitely, until disconnected. (This requires a thread and will not work if you use runserver’s --nothreading option.)

On a relevant event, the worker will reload the most recently connected tab. (It avoids reloading all tabs since that could be expensive.)

To reload when a template changes, django-browser-reload piggybacks on Django’s autoreloading infrastructure. An internal Django signal indicates when a template file has changed. The events view receives this signal and sends an event to the worker, which triggers a reload. There is no smart filtering - if any template file changes, the view is reloaded.

To reload when the server restarts, django-browser-reload uses a version ID. This ID is randomly generated when the view module is imported, so it will be different every time the server starts. When the server restarts, the worker’s EventSource reconnects with minimal delay. On connection, the events view sends the version ID, which the worker sees as different, so it triggers a reload.

The events view also sends the version ID every second to keep the connection alive.