flask: Jinja templates do not auto reload if Flask app debug enabled solely via app.run(debug=True)

For me it worked with the following code:

if __name__ == '__main__':
    app.jinja_env.auto_reload = True
    app.config['TEMPLATES_AUTO_RELOAD'] = True
    app.run(debug=True, host='0.0.0.0')

Is this still an issue? auto reload doesn’t seem to work at all @patricksurry doing app.config explicitly doesn’t do anything for me… was wondering why this would be

Even a simple hello world app doesn’t want to reload

from flask import Flask, render_template
app = Flask(__name__)

@app.route("/")
def hello():
    return "hello world"

if __name__ == "__main__":
    app.config['TEMPLATES_AUTO_RELOAD']=True
    app.run(debug=True,use_reloader=True)

I think I’m running into the same issue, if I configure custom jinja filters via @app.template_filter('format_date'). This stops auto-template reloading.

If I explicitly say app.config['TEMPLATES_AUTO_RELOAD'] = True before that, reloading works again.

Just to add here, since this thread helped me, the app.jinja_env.auto_reload = True made it work for me again.

To summarize for posterity: if you touch the Jinja2 environment in any way before the app.run call (e.g. adding a filter), you will need the line above before app.run for your templates to be auto-reloaded after changes. This is at least what I’ve observed.

Thanks to folks here on the resolution, saved me some trouble. 😺

To those out there who may be facing the same problem using a factory pattern.

Maybe the following post has something to do with you.

https://blog.socratic.org/the-one-weird-trick-that-cut-our-flask-page-load-time-by-70-87145335f679#.biy44wahq

When I removed the following line of code from my factory pattern, I was able to just refresh the browser and the changes from the html appeared. It seems the template changes did take affect after you reload. However the flask app in terminal did not say anything about detection on the html file. Maybe we can add some sort of detection on there to let developers know what file was changed.

app.jinja_env.cache = {}

Hope this helps out some people.

Cheers!

Your proposed fix makes sense to me.