如何使用NodeRED的Switch节点解析数组并提取值

Question

A quick NodeRed question as I am not sure I am correct in my approach.

I'd like to visualize my laptop's CPU usage value to a gauge. My laptop is a quad-core, having 4 CPU's.

With that, NodeRED's CPU usage node returns the following array when debugged:

{"payload":29,"topic":"core_1","model":"Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz","speed":2300,"_msgid":"1a846a9b.631375"}

{"payload":13,"topic":"core_2","model":"Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz","speed":2300,"_msgid":"1a846a9b.631375"}

{"payload":27,"topic":"core_3","model":"Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz","speed":2300,"_msgid":"1a846a9b.631375"}

{"payload":14,"topic":"core_4","model":"Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz","speed":2300,"_msgid":"1a846a9b.631375"}

Each cpu is represented, indicated by the "topic" value.

With that in mind, I wired up program to extract the each payloads value via the Switch node, to then be sent to debug.

 [{"id":"bb8b8d89.ff51f","type":"cpu","z":"c5c8a205.2f99a","name":"","msgCore":true,"msgOverall":false,"x":270,"y":140,"wires":[["4acb9cc9.1dea24","d55a24f8.0811a8"]]},{"id":"a1805033.6df75","type":"inject","z":"c5c8a205.2f99a","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":120,"y":140,"wires":[["bb8b8d89.ff51f"]]},{"id":"c3a48e9d.2f8de","type":"debug","z":"c5c8a205.2f99a","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":310,"y":200,"wires":[]},{"id":"4acb9cc9.1dea24","type":"switch","z":"c5c8a205.2f99a","name":"CPU Parse","property":"payload","propertyType":"msg","rules":[{"t":"eq","v":"core_1","vt":"msg"},{"t":"eq","v":"core_2","vt":"msg"},{"t":"eq","v":"core_3","vt":"msg"},{"t":"eq","v":"core_4","vt":"msg"}],"checkall":"true","repair":false,"outputs":4,"x":130,"y":220,"wires":[["c3a48e9d.2f8de"],["55530c03.0256b4"],["bd6f5bb7.283058"],["70265266.692dec"]]},{"id":"55530c03.0256b4","type":"debug","z":"c5c8a205.2f99a","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":310,"y":240,"wires":[]},{"id":"bd6f5bb7.283058","type":"debug","z":"c5c8a205.2f99a","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":310,"y":280,"wires":[]},{"id":"70265266.692dec","type":"debug","z":"c5c8a205.2f99a","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":310,"y":320,"wires":[]},{"id":"d55a24f8.0811a8","type":"debug","z":"c5c8a205.2f99a","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","x":490,"y":140,"wires":[]},{"id":"b0d4e3d4.7e538","type":"ui_gauge","z":"c5c8a205.2f99a","name":"","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{value}}","min":0,"max":10,"colors":["#00B500","#E6E600","#CA3838"],"seg1":"","seg2":"","x":490,"y":200,"wires":[]},{"id":"9c6e57f2.cdc4f8","type":"ui_gauge","z":"c5c8a205.2f99a","name":"","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{value}}","min":0,"max":10,"colors":["#00B500","#E6E600","#CA3838"],"seg1":"","seg2":"","x":490,"y":240,"wires":[]},{"id":"5fa0cda1.ad7074","type":"ui_gauge","z":"c5c8a205.2f99a","name":"","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{value}}","min":0,"max":10,"colors":["#00B500","#E6E600","#CA3838"],"seg1":"","seg2":"","x":490,"y":280,"wires":[]},{"id":"924f895e.acc578","type":"ui_gauge","z":"c5c8a205.2f99a","name":"","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{value}}","min":0,"max":10,"colors":["#00B500","#E6E600","#CA3838"],"seg1":"","seg2":"","x":490,"y":320,"wires":[]}] 

This approach may be incorrect as I am not sure whether the CPU Usage node will return the desired values. But assuming that this is the correct approach, I've configured the Switch node in the following manner:

As mentioned, this may not be the correct approach. Any insights you can provide will be incredibly helpful.

Many thanks!

Answer 1

It's not returning an array, it's returning 4 separate messages, one for each core.

It's identifying each core by settings the msg.topic to core_1 , core_2 , core_3 and core_4 respectively. So change your switch node to route based on msg.topic not msg.payload and have it compare to a string not a msg property