Reuse a Node Red flow for multiple devices

The key for me was the ability to extract strings from mqtt topics (msg.topic) with regex’s.

Eg. using node red’s Change node and jsonata expressions:

$match(topic, /binary_sensor.(cam_\w{5})_motion/).groups[0].$string()

That gives you ‘bacon’ in binary_sensor.cam_bacon_motion. Set to that and the flow can be used for anything matching the regex. Moreover, you can use $ in the same change node to set other msg.*

It’s really powerful.

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