Wildcard in a Javascript Object

[David Dempster]

Hi to all,
I'm trying to get a value from a Javascript object that has various levels.

If I use the following in Function Node it works fine.

var data = msg.payload["Time Series (1min)"]["2017-09-08 11:01:00"]["1. open"];

msg.payload = data;

return msg;

What I would like to do is make the Function Node pick up the FIRST entry for the datestamp, like the following.

// var data = msg.payload["Time Series (1min)"][0]["1. open"];

I don't really care what the datestamp is, I just want the first one at the top of the list.

Any help/guidance would be appreciated.

Kind regards from David (Dempster)

[Nick O'Leary]

Can you share an example of your actual data - to remove any ambiguity?

Nick

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[David Dempster]

Here's a screenshot - trust it makes sense.

Thanks in advance for your help.

Rdgs - David

[steve rickus]

As usual, I'm looking at this as a puzzle to be solved using JSONata ;*)

Assuming that you may want data from time series of any time period (not just "1 min"), I used a jsonata $sift() function to get whichever field starts with "Time Series". I then spread that object into separate objects and retrieve only the first one (presumably that is the latest timestamp). From that object, use the $sift() function again to grab the field starting with "1." The resulting string should  be what you want => "555.0000"

payload
   .$sift(function($v,$k) { $k ~> /^Time Series/ }).*
   .$spread()[0].*
   .$sift(function($v,$k) { $k ~> /^1\. / }).*

Granted, not nearly as readable as the javascript syntax you were wishing for -- but you should be able to put this expression in a change node, replacing the msg.payload with this result.

--

Steve

[Nick O'Leary]

For the regular JavaScript version:

var timeSeriesData = msg.payload["Time Series (1min)"];

// The properties of a JavaScript object don't have a natural order.

// So we have to:

// 1. get the keys

var timeslots = Object.keys(timeSeriesData);

// 2. sort them to ensure they are in order - the format of the timestamp makes this easy

timeslots.sort();

// 3. grab the last one

var lastTimeSlotKey = timeslots.pop();

// 4. grab the actual data:

msg.payload = timeSeriesData[lastTimeSlotKey]["1. open"];

return msg;

Nick

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[David Dempster]

A big "thank you" to Steve and Nick for their brilliant responses.

At the moment I've implemented Nick's version as I could follow what is going on.

I'm going to work out the syntax of Steve's version later today as it also looks "neat".

Like a lot of things in life, once you've seen the solution - it all makes sense (and you think "why on earth didn't I think of that").

Thanks again for all your help/guidance.

Have a great weekend.

On Friday, September 8, 2017 at 6:54:02 PM UTC+1, David Dempster wrote: