Efficient Real-Time Comment Updates in Anvil: Alternatives to Polling?

Anvil Q&A
1

What I’m trying to do:
I’m building a commenting system for posts in my Anvil app. Currently, I’m using a timer to periodically check for new comments, but I’m looking for a more efficient method that doesn’t require frequent server calls.

What I’ve tried:
I’ve implemented a timer-based system that checks for new comments every 2 seconds. While this works, it’s not ideal as it leads to a lot of server calls, especially when there are multiple users. Here’s a simplified version of my current approach:

Code Sample:

class CommentSystem:
    def __init__(self):
        self.timer = Timer(interval=2)
        self.timer.set_event_handler('tick', self.check_for_new_comments)
        self.add_component(self.timer)

    def check_for_new_comments(self, **event_args):
        new_comments = anvil.server.call('get_new_comments', self.last_check_time)
        if new_comments:
            self.call_js('updateComments',new_comments)
            self.last_check_time = datetime.now()

    def start_checking(self):
        self.last_check_time = datetime.now()
        self.timer.interval = 2

    def stop_checking(self):
        self.timer.interval = 0

Is there a more efficient way to implement real-time updates in Anvil, perhaps using a database listener or a push-based system? I’m looking for a method that could trigger updates on the client side based on new data in the database, without requiring frequent polling.

2

No. There is currently no other way to do this by default. You can do it using Firebase however Unofficial Anvil Firebase Integration v0.1🔥

Otherwise, I don’t think there is any problem with frequent server calls. Mostly everyone here uses it (including myself) and it shouldn’t make things any worse in my opinion.

1 Like
3

you should just put this in a no_loading_indicator like:

with anvil.server.no_loading_indicator:
    new_comments = anvil.server.call('get_new_comments', self.last_check_time)

…then it will just look like the comments appear in the background and the user does not notice, especially if you combine it with something like: