Python Based Real-time connection

[sturdy delta]

Hey any plans to make the https://github.com/get-convex/convex-py client library reactive. Something like a websocket handler like:

@on_change_query("file:rpc")
def on_change(query_result: QueryResult):
  # handle logic

@on_change_table("table...")
def on_change(record: RecordChangeEvent):
  # handle logic

I have some backend services that need python and would love it if there was a way for me to handle side effects in my python code. I know the workaround with actions, etc and pushing the behavior to my app but i would love it if the python portion of my code was also reactive! Thanks!

[tidal apex]

Thanks for posting in #1088161997662724167.
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[onyx wind]

check out the usage example here which makes use of the subscribe method:

https://github.com/get-convex/convex-py?tab=readme-ov-file#convex

[quasi meteor]

@sturdy delta you could totally write a decorator that does this! You'd be subscribing to a Convex query function, not a table change—but that Convex query function can read whatever tables you want.

[sturdy delta]

oh wow blind of me 😦 i missed the subscribe option 😂 i saw the rest of the mutations and didnt realize there is a subscribe this is amazing!

[quasi meteor]

@sturdy delta are you using async Python? There's a PR for async iteration and I've thought about this, but right now whether you want to use threads or asyncio is up to you

[sturdy delta]

prefer asyncio i am currently running backend on modal functions. and i would like to dispatch containers for longer durable python code execution when a new entry happens.

[quasi meteor]

I've found it easiest to run a thread that blocks on the subscription updates and use threadsafe queues to get communicate back to the rest of process

Cool, shouldn't be hard to hook up with the usual asyncio adapters for blocking calls but I'd be interested in making this more convenient for cases like yours

[sturdy delta]

but standard loops also work. just curious based on the example when subscribing to a list query are the list of messages deduped or is the list query republish all the results to the python client

[quasi meteor]

Each time you get the entire new query result (so in that example, list of messages) so if you want to use it like a work queue you should write a Convex query function that returns all "unclaimed" tasks and have yorurPython server "claim" the task by writing to the DB

subscriptions in Convex are always on the result of a query funciton, so the naive way to get changes is to diff these results on the client (but that doesnt' scale well)

so you probably want to write a function that returns whichever entities you're intrested in, e.g. "job.status === 'unclaimed'"

[sturdy delta]

cool this is pretty slick... to scale out large jobs that require gpus/multiple cores... with very little code and logic!