This is a job for the template node
e.g.
[{"id":"b75fcc44.64f79","type":"inject","z":"b779de97.b1b46","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":130,"y":4840,"wires":[["fafe62fc.c05b88"]]},{"id":"fafe62fc.c05b88","type":"template","z":"b779de97.b1b46","name":"","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"{\"a\": {{global.load_v}}, \"b\": {{global.fan_v}}, \"c\": {{global.fan_a}}}","output":"str","x":290,"y":4840,"wires":[["51b9b0de.3f9dd"]]},{"id":"51b9b0de.3f9dd","type":"debug","z":"b779de97.b1b46","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":500,"y":4840,"wires":[]}]
{"a": {{global.load_v}}, "b": {{global.fan_v}}, "c": {{global.fan_a}}}
from the template help info
It is possible to use a property from the flow context or global context. Just use {{flow.name}}
or {{global.name}}
, or for persistable store store
use {{flow[store].name}}
or {{global[store].name}}
.