Hi all! I want to extract a message element by a known path, but dynamically (via dropwdown or inputstring). How can I do this? Thanks for help on this!

No. Don't use eval. It is fraught with danger. Use RED.util.getObjectProperty See similar thread here : Alternatives to eval() - #2 by Steve-Mcl

If the element path is in the variable path then you can use msg[path] to address that element in the message.

I'm not sure understanding you right, but the [path] should be user definable and not hardcoded. [image] I want the user to let him choose, wich parameter he wants to see visualized of a large dataset.

path is a variable which you got from the input string. So if that is in the payload and your object is in msg.JsonDatset__DataCycleModuleDataset then you can use, in a Function node msg.JsonDatset__DataCycleModuleDataset[msg.payload]

This should work: var userinput = "measureDataset.measureData[0].cellsensitivity" msg.payload = msg.JsonDataset__DataCycleModuleDataset[userinput] But you will presumably have to devise a way to translate a simple user selection such as "Sensitivity" into "measureDataset.measureData[0].cellsens…

Sounds good, but is not working... [image]

[{"id":"7f526c4d.e81224","type":"debug","z":"193cbcd5.135b83","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":430,"y":520,"wires":[]},{"id":"c647637b.689c1","type":"inject","z":"193cbcd5.135b83","name":"","props":[{"…

Ah, no, that won't work. You can't have multiple levels in the path variable. You can do msg.payload["a"]["b"] but you can't do msg.payload["a.b"] which is what you want to do (where the string is actually a variable but that doesn't make any difference). I am not sure how to solve that.

Ok, damn. is there any chance to use JSONata? I mean, feed a jsonata searchstring by a message string?

[image] protonmw: is there any chance to use JSONata I don't know, but when I said I didn't know how to do it in JS, I meant that someone else surely does. I haven't found it so far but likely someone will interject with the solution.

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Dynamic Objectpath for extracting an element

General

Colin 13 September 2021 10:39 7

Please export that flow so that we can try it ourselves. See this post how to post a flow - How to share code or flow json

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Dynamic Objectpath for extracting an element

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