!!! note This post is a thought. It's a short note that I make about someone else's content online. Learn more about the process here

Here's my thought on 💭 Automatic browser reloading in FastAPI

I just discovered arel for hot reloading python applications when content changes from this snippet that implements it for fatapi.

On app startup add the /hot-reload routes if in DEBUG mode.

import os

import arel
from fastapi import FastAPI, Request
from fastapi.templating import Jinja2Templates

app = FastAPI()
templates = Jinja2Templates("templates")

if _debug := os.getenv("DEBUG"):
    hot_reload = arel.HotReload(paths=[arel.Path(".")])
    app.add_websocket_route("/hot-reload", route=hot_reload, name="hot-reload")
    app.add_event_handler("startup", hot_reload.startup)
    app.add_event_handler("shutdown", hot_reload.shutdown)
    templates.env.globals["DEBUG"] = _debug
    templates.env.globals["hot_reload"] = hot_reload

def index(request: Request):
    return templates.TemplateResponse("index.html", context={"request": request})

# run:
# DEBUG=true uvicorn main:app --reload

install arel and make sure you have uvicorn[standard] for websocket support.


In the template, load the script when in debug mode.

  {% block content %}{% endblock %}

  <!-- Hot reload script -->
  {% if DEBUG %} {{ hot_reload.script(url_for('hot-reload')) | safe }} {% endif

This post was a thought by Waylon Walker see all my thoughts at https://waylonwalker.com/thoughts