Aliases for send values

[FreakErn]

I have a Ikea On/Off switch which sends the values like:

{"action":"on","battery":87,"click":"on","linkquality":0,"update":{"state":"idle"},"update_available":false}

Is there a easy way to rename the action result "on" to "power_up"?

Can this be archived by using a external_converter?

Thanks in advance