How to call a Python script (and get data back) on demand?

Configuration
1

I’ve set Blue Iris and Plate Recognizer up to pass any detected license plates of cars on my drive to Home Assistant via MQTT. I have a Python script which will call a restful API (restful sensor didn’t like the data format) and when called as a command line sensor, will set various car vehicle related attributes.

The problem with the command line sensor though is it’s constantly being called, and I just want to call this API when a new plate is posted via MQTT. I have an automation to act on a new plate appearing, but I have no idea how to call the script/API from the automation such that it gets data back into HA.

What’s the best way to go about this?

2

Run it with a shell_command and send the data to HA via mqtt within the script.

Or… keep the command_line sensor as it is, and just set a very large scan_interval, so that it doesn’t get called that often.

Afterwards, you can call it when needed with the homeassistant.update_entity service.

3

Thank you. I’d just started contemplating the shell command & MQTT option, but wasn’t aware of the update_entity possibility.