How to access app_id and partition_key inside an action?

[shun-liang]

Dear burr developers

Sorry if it's obivous, but in the documentation I haven't found any information about how to access app_id and partition_key inside an action. Can you give me some information on this? Many thanks.

[skrawcz]

Yes, you're right this isn't in the docs. We need to add that. You can access it in the action by declaring a __context: ApplicationContext parameter, and then accessing it like so:

from burr.core import action, State, ApplicationContext

@action(reads=["..."], writes=["..."])
def my_action(state: State, __context: ApplicationContext) -> State:
    print(__context.app_id, __context.partition_key, __context.sequence_id)
    ...

See this notebook for example usage.

[skrawcz]

Added note in the docs here for now.

[shun-liang]

Thanks for the answer @skrawcz . Can you please also add an example achieving the same but with a class-based action?

[skrawcz]

ah yep - found a minor bug with python name mangling. Will fix today and push it out later tonight.

[skrawcz]

I added an example to the bottom of https://burr.dagworks.io/concepts/actions/#class-based-actions
Note this requires the latest burr==0.34.0.