Problem with Jsonata function $toMillis

General
1

I see a strange error thrown by the JSONATA $toMillis() function, when I try to process a payload from the feedparser node.

  • The 'article.date' field from the feedparser node seems to yield a perfect DateTime string.
  • When I send it directly to a CHANGE node with "Set msg.payload to [Jsonata]$toMillis(payload) I get an error:

Invalid JSONata expression: Argument 1 of function "toMillis" does not match function signature

-When I take the payload string from the DEBUG node and INJECT it to the same CHANGE node, I get the correct result.

I'm clueless. Any suggestions ?!

Here the example flow:

[{"id":"4f58bfb4.3dbd3","type":"inject","z":"66117b0a.627124","name":"Timestamp","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"2021-03-11T07:04:00.000Z","payloadType":"str","x":230,"y":940,"wires":[["abb60e71.a108e8"]]},{"id":"19791ded.25089a","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":670,"y":760,"wires":[]},{"id":"763dd87d.e23a68","type":"feedparse","z":"66117b0a.627124","name":"Heise","url":"https://www.heise.de/rss/heise-atom.xml","interval":"120","x":70,"y":840,"wires":[["17b52f3.021a951"]]},{"id":"17b52f3.021a951","type":"trigger","z":"66117b0a.627124","name":"","op1":"","op2":"0","op1type":"pay","op2type":"str","duration":"0","extend":false,"overrideDelay":false,"units":"ms","reset":"","bytopic":"all","topic":"topic","outputs":1,"x":250,"y":840,"wires":[["19791ded.25089a","f82ddcce.bd3278"]]},{"id":"f82ddcce.bd3278","type":"change","z":"66117b0a.627124","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"article.date","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":470,"y":820,"wires":[["617be7c.0f74c98","abb60e71.a108e8"]]},{"id":"617be7c.0f74c98","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":670,"y":820,"wires":[]},{"id":"abb60e71.a108e8","type":"change","z":"66117b0a.627124","name":"Jsonata $toMillis","rules":[{"t":"set","p":"payload","pt":"msg","to":"$toMillis(payload)","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":500,"y":880,"wires":[["ad804cbb.85b5a"]]},{"id":"ad804cbb.85b5a","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":670,"y":880,"wires":[]}]
2

article.date as set in first change node seems wrong. can we see a debug of msg going into this change node?

3

Thanks, this is msg object going into change node set msg.payload:

{"topic":"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag","payload":"<p><a href=\"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag\"><img src=\"https://www.heise.de/scale/geometry/450/q80//imgs/18/3/0/6/9/8/4/3/vsc-6e0729f85d8457df.png\" class=\"webfeedsFeaturedVisual\" alt=\"\" /></a></p><p>Microsoft hat seinen quelloffenen Developer-Editor nun für ARM-Macs angepasst. Das Update verspricht Leistungsgewinne.</p>","article":{"title":"Visual Studio Code kommt für Apples ARM-Macs","description":"<p><a href=\"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag\"><img src=\"https://www.heise.de/scale/geometry/450/q80//imgs/18/3/0/6/9/8/4/3/vsc-6e0729f85d8457df.png\" class=\"webfeedsFeaturedVisual\" alt=\"\" /></a></p><p>Microsoft hat seinen quelloffenen Developer-Editor nun für ARM-Macs angepasst. Das Update verspricht Leistungsgewinne.</p>","summary":"Microsoft hat seinen quelloffenen Developer-Editor nun für ARM-Macs angepasst. Das Update verspricht Leistungsgewinne.","date":"2021-03-11T08:30:00.000Z","pubdate":"2021-03-11T08:30:00.000Z","pubDate":"2021-03-11T08:30:00.000Z","link":"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag","guid":"http://heise.de/-5076987","author":"heise online","comments":null,"origlink":null,"image":{},"source":{},"categories":[],"enclosures":[],"atom:@":{},"atom:title":{"@":{"type":"text"},"#":"Visual Studio Code kommt für Apples ARM-Macs"},"atom:id":{"@":{},"#":"http://heise.de/-5076987"},"atom:updated":{"@":{},"#":"2021-03-11T09:30:00+01:00"},"atom:published":{"@":{},"#":"2021-03-11T09:30:00+01:00"},"atom:link":{"@":{"href":"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag"}},"atom:summary":{"@":{"type":"html"},"#":"Microsoft hat seinen quelloffenen Developer-Editor nun für ARM-Macs angepasst. Das Update verspricht Leistungsgewinne."},"atom:content":{"@":{"type":"html"},"#":"<p><a href=\"https://www.heise.de/news/Visual-Studio-Code-kommt-fuer-Apple-Silicon-5076987.html?wt_mc=rss.red.ho.ho.atom.beitrag.beitrag\"><img src=\"https://www.heise.de/scale/geometry/450/q80//imgs/18/3/0/6/9/8/4/3/vsc-6e0729f85d8457df.png\" class=\"webfeedsFeaturedVisual\" alt=\"\" /></a></p><p>Microsoft hat seinen quelloffenen Developer-Editor nun für ARM-Macs angepasst. Das Update verspricht Leistungsgewinne.</p>"},"meta":{"#ns":[{"xmlns":"http://www.w3.org/2005/Atom"}],"@":[{"xmlns":"http://www.w3.org/2005/Atom"}],"#xml":{"version":"1.0","encoding":"utf-8"},"#type":"atom","#version":"1.0","title":"heise online News","description":"Nachrichten nicht nur aus der Welt der Computer","date":"2021-03-11T08:30:00.000Z","pubdate":"2021-03-11T08:30:00.000Z","pubDate":"2021-03-11T08:30:00.000Z","link":"https://www.heise.de/","xmlurl":"https://www.heise.de/rss/heise-atom.xml","xmlUrl":"https://www.heise.de/rss/heise-atom.xml","author":"heise online","language":null,"favicon":null,"copyright":"Copyright (c) 2021 Heise Medien","generator":null,"cloud":{},"image":{},"categories":[],"atom:@":{"xmlns":"http://www.w3.org/2005/Atom"},"atom:title":{"@":{"type":"text"},"#":"heise online News"},"atom:subtitle":{"@":{"type":"html"},"#":"Nachrichten nicht nur aus der Welt der Computer"},"atom:updated":{"@":{},"#":"2021-03-11T09:30:00+01:00"},"atom:id":{"@":{},"#":"https://www.heise.de/rss/heise-atom.xml"},"atom:author":{"@":{},"name":{"@":{},"#":"heise online"},"uri":{"@":{},"#":"https://www.heise.de"}},"atom:link":[{"@":{"rel":"self","type":"application/atom+xml","href":"https://www.heise.de/rss/heise-atom.xml"}},{"@":{"rel":"alternate","type":"text/html","href":"https://www.heise.de/"}}],"atom:rights":{"@":{},"#":"Copyright (c) 2021 Heise Medien"}}},"_msgid":"8bcc8b27.364478"}
4

Ok with that data everything works as it should this end. So i am failing to understand what is going wrong for you.
As seen in this image.

Screenshot_20210311-091347
Screenshot_20210311-0913471920×1080 232 KB

The function just creates the payload and article objects, pasted from your debug.

5

Huuuuh, finally found it:

The feedparser node sends a JavaScript Date-Object in the attribute article.date !
(See line 28 in the source of the underlying JavaScript feedparser node at GitHub.)

This is totally obscured by the Node_RED GUI (!) which shows a string as debug output.
But naturally JSONATA fails, because it only handles strings.

To solve this I now change the attribute in a function node:

msg.payload = msg.payload.toISOString();
return msg;

Here the whole example flow:

[{"id":"17b52f3.021a951","type":"trigger","z":"66117b0a.627124","name":"","op1":"","op2":"0","op1type":"pay","op2type":"str","duration":"0","extend":false,"overrideDelay":false,"units":"ms","reset":"","bytopic":"all","topic":"topic","outputs":1,"x":300,"y":820,"wires":[["f82ddcce.bd3278"]]},{"id":"f82ddcce.bd3278","type":"change","z":"66117b0a.627124","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"article.date","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":520,"y":820,"wires":[["617be7c.0f74c98","ac9811bf.c7e59","fba4f7ca.92d86"]]},{"id":"617be7c.0f74c98","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":730,"y":820,"wires":[]},{"id":"abb60e71.a108e8","type":"change","z":"66117b0a.627124","name":"Jsonata $toMillis","rules":[{"t":"set","p":"payload","pt":"msg","to":"$toMillis(payload)","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":600,"y":880,"wires":[["ad804cbb.85b5a"]]},{"id":"ad804cbb.85b5a","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":770,"y":880,"wires":[]},{"id":"441e3174.9974e8","type":"feedparse","z":"66117b0a.627124","name":"NYT","url":"https://rss.nytimes.com/services/xml/rss/nyt/Technology.xml","interval":"120","x":90,"y":820,"wires":[["17b52f3.021a951"]]},{"id":"ac9811bf.c7e59","type":"function","z":"66117b0a.627124","name":"","func":"msg.payload = msg.payload.toISOString();\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":420,"y":880,"wires":[["abb60e71.a108e8"]]},{"id":"fba4f7ca.92d86","type":"change","z":"66117b0a.627124","name":"Jsonata $toMillis","rules":[{"t":"set","p":"payload","pt":"msg","to":"$toMillis(payload)","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":600,"y":940,"wires":[["63867716.5cf438"]]},{"id":"63867716.5cf438","type":"debug","z":"66117b0a.627124","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"true","targetType":"full","statusVal":"payload","statusType":"auto","x":770,"y":940,"wires":[]}]

@dceejay - It's a bad thing, that it is not visible in the GUI, that some attributes of feedparser node output are not, what the debug node shows. I am not sure, if this should be sanitized by a type cast to the ISO date string that is already automagically shown in debug node or how this tripping hazard may be cleared.

1 Like
6

It does not seem right to convert a Date object (which internally is actually the milliseconds value) to a string then use JSONata to convert it back to milliseconds. Alternatively, in the function node you could convert it directly to milliseconds.
msg.payload = msg.payload.getTime()

7

That makes sense. The same thing in jsonata would be to convert to string and remove \" from the string

$toMillis($replace($string(payload),/\"/, ""))
8

Yes, you're right. It seems not good to convert the attributes there and back.
But it is a bad thing that the real object type is invisble in the GUI editor.

9

If you set the debug to show msg.article.date it does show you the correct type
image

there is no standard way to depict different types in a log as far as I know - so we chose to approximately follow the chrome browser javascript log convention.

10

Ok, you are right. I have to learn more about node-red debugging :thinking:

11

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