Context variable holding other context variables

General
1

I have a context variable and would like to create a JSON object as a new context variable where the previous context variable value is inserted. How should that be written?

Imagine the simple example below

The first inject node just sends a "Hello" string to a change node that sets the received payload to the flow.out variable. The second inject node should trigger the creation of a new variable as a JSON object where the value of the first should be included. But obviously I fail in trying different variants like

{"captured":flow.get('out')} (a wish this should work but it will of course not)

In JSONATA the method to do this is simple, $flowContext('out') but what would be the correct syntax in my example above?

Greatful for any hint!

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2

Have you tried ...

{"captured": $flowContext('out')}
3

Agree, that would be nice if it worked

But it gives
"Invalid 'to' JSON property"

4

Also tried below but no :disappointed:
{"captured": "$flowContext('out'), value"}

5

Works fine for me...

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[{"id":"eaeef752fb45e58c","type":"inject","z":"3422959b.40de62","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payloadType":"date","x":1720,"y":80,"wires":[["33a6944a1892c763"]]},{"id":"33a6944a1892c763","type":"change","z":"3422959b.40de62","name":"","rules":[{"t":"set","p":"out","pt":"flow","to":"hello","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"{\"captured\": $flowContext('out')}","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":1730,"y":140,"wires":[["8d537c9c2c79c9fe"]]},{"id":"8d537c9c2c79c9fe","type":"debug","z":"3422959b.40de62","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":1730,"y":200,"wires":[]}]
6

Well, in my example I wanted the result pushed to a new flow variable directly, creating a new JSON object, and not "walk the distance" via JSONATA to msg.payload and finally push it to context. You got me anyway on a working track, so thanks! With that "extra step" like below, it works

But it would be preferrable if it could be done in one single shot. I think...
Best regards, Walter

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7

Like this?

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8

No, the out result shall be a JSON object, not a string

9

Sorry Walter, you lost me.

Both your example and the one line entry I just posted will create a JavaScript object stored in flow.in - there is no difference.

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[{"id":"eaeef752fb45e58c","type":"inject","z":"3422959b.40de62","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payloadType":"date","x":1720,"y":80,"wires":[["33a6944a1892c763"]]},{"id":"33a6944a1892c763","type":"change","z":"3422959b.40de62","name":"","rules":[{"t":"set","p":"out","pt":"flow","to":"hello","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"{\"captured\": $flowContext('out')}","tot":"jsonata"},{"t":"set","p":"in","pt":"flow","to":"payload","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":1730,"y":140,"wires":[[]]},{"id":"21debea693fd511f","type":"inject","z":"3422959b.40de62","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payloadType":"date","x":1720,"y":200,"wires":[["0f0861ea0272e6aa"]]},{"id":"0f0861ea0272e6aa","type":"change","z":"3422959b.40de62","name":"","rules":[{"t":"set","p":"in2","pt":"flow","to":"{\"captured\": $flowContext('out')}","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":1720,"y":260,"wires":[[]]}]

Perhaps I am missing something or I misunderstood your requirement.

PS for clarity, JSON object is not a thing. JSON is a string representation of a JavaScript object.

10

This post should help to clarify the difference between Javascript objects and JSON.

11

Yeah, I'm expressing myself unclear, whatever, I want to set it in an expression like below. And that is not working

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12

That is not working because you have the type set to "JSON". Change the type to JSONata Expression.

13

As Nick said and as I pointed out earlier...

↑ note the J: in the screenshot and in the demo flow I posted.

Are you all sorted now Walter?

14

Yes, thank you all !!

Best regards, Walter

15

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