How to Implement Event Filter in event subscription

[arunkumar790]

I am developing client and trying to subscribe event with event filter option
I don't know how to implement it, My expectation is using the event filter receive only specific attributes in the event notification. Like i want to receive only "EventId", "SourceNode","Severity" but not all attributes
Could anyone help, any example would be great

obj = await client.nodes.root.get_child(["0:Objects", "2:MyObject"])
myevent = await client.nodes.root.get_child(["0:Types", "0:EventTypes", "0:BaseEventType", "2:MyEvent"])
evfilter = ???

handle = await self.subscription.subscribe_events(obj, myevent, evfilter)

Thanks

[kevinPolo]

You can import the get_filter_from_event_type function from events.py:

from asyncua.common.events import get_filter_from_event_type
...
myevent = await client.nodes.root.get_child(["0:Types", "0:EventTypes", "0:BaseEventType", "2:MyEvent"])
event_filter = await get_filter_from_event_type([myevent])

event_filter is an asyncua.ua.EventFilter object with 'Select' clauses and 'Where' clauses:

https://reference.opcfoundation.org/v105/Core/docs/Part4/7.22.3

You can then delete some of the Select clauses and subscribe with this reduced filter.

perform deletion by comparing the browse path or something else..

handle = await self.subscription.subscribe_events(obj, myevent, event_filter)

Or directly create the event_filter object with the Select clauses of SimpleAttributeOperand type (list).

[arunkumar790]

@kevinPolo Thanks a lot, these two approaches will be helpful