How to switch based on array value

[omega_elite]

Hi

i am new to node red and would like to know how to do the following.

I have 8 digital input values( true or false ) that are coming in on msg.payload as an array [false,false,false,false,false,false,false,false] and i would like to trigger outputs based on the true or false value of each array index.

[Steve-Mcl]

You could do a few ways. Off the top of my head:

• via a function node set to have 8 output and the code set to return msg.payload.map(e => {return {payload:e}})
• wire the msg to 8 change nodes that SETs the value of msg.payload to msg.payload[x] (where x is 0~7)

@omega_elite

i am new to node red

I recommend watching this playlist: Node-RED Essentials. The videos are done by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in about 1 hour. A small investment for a lot of gain.

[dynamicdave]

@Steve-Mcl

via a function node set to have 8 output and the code set to return msg.payload.map(e => {return {payload:e}})

Here's a quick demo using Steve's Map Method...

And here's the Node-RED flow, so you can Import it and try it out...

[{"id":"d0d670bd0a5b6772","type":"tab","label":"Map function demo","disabled":false,"info":"","env":[]},{"id":"8959eb7e7a67cc21","type":"function","z":"d0d670bd0a5b6772","name":"Array Mapping","func":"// return msg.payload.map(e => ({ payload: e }));\n\n// Return only if an input is true, null is false\n// Uncomment the next line and comment-out the first line\n \nreturn msg.payload.map(e => e ? { payload: e } : null);","outputs":8,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":560,"y":280,"wires":[["e0b650c1687fc97f"],["2676a4a1c86798e0"],["7087deea270ed147"],["815e704f0cc8b762"],["d4e24d66b9a144bc"],["d335eb5abfe68df1"],["b89a22a259ce35ea"],["c70a2db23ac35081"]]},{"id":"2267674ab1c3bbd6","type":"inject","z":"d0d670bd0a5b6772","name":"Test","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"true","payloadType":"bool","x":210,"y":280,"wires":[["de7de090fd54ad38"]]},{"id":"de7de090fd54ad38","type":"function","z":"d0d670bd0a5b6772","name":"Array pattern","func":"msg.payload = [true,false,false,false,false,false,false,false];\nreturn msg;","outputs":1,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":370,"y":280,"wires":[["8959eb7e7a67cc21"]]},{"id":"e0b650c1687fc97f","type":"debug","z":"d0d670bd0a5b6772","name":"MSB","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":790,"y":140,"wires":[]},{"id":"2676a4a1c86798e0","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3575","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":180,"wires":[]},{"id":"7087deea270ed147","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3576","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":220,"wires":[]},{"id":"815e704f0cc8b762","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3577","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":260,"wires":[]},{"id":"d4e24d66b9a144bc","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3578","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":300,"wires":[]},{"id":"d335eb5abfe68df1","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3579","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":340,"wires":[]},{"id":"b89a22a259ce35ea","type":"debug","z":"d0d670bd0a5b6772","name":"debug 3580","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":810,"y":380,"wires":[]},{"id":"c70a2db23ac35081","type":"debug","z":"d0d670bd0a5b6772","name":"LSB","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":790,"y":420,"wires":[]},{"id":"25dfae1fd97e1bfd","type":"comment","z":"d0d670bd0a5b6772","name":"Using .map method","info":"","x":570,"y":200,"wires":[]}]

The JavaScript in the function node can be adapted so only inputs that are 'true' are shown on the outport port(s) by using this...

return msg.payload.map(e => e ? { payload: e } : null);

[Colin]

There may be a simpler way, exactly how do you trigger an output?