Hi! Im a beginner and still learning NodeRed. I have browsed through the forums to try to find information. However Im stuck. I have a table in the database that I want to pull some data from. each line from the database query looks like this: time: "2022-09-20T07:58:55.000Z" outdoortemperature: 13 loggedoutdoortemp: 10 What I want the line chart to show is how the two temperatures change and corelate over time. I have created a change node with a J:expression (found that in a tutorial) This is my J:expression code: [{"series" : [$distinct(time)], "data":$each(payload{time:loggedoutdoortemp},function($val){$val}) }] I know it probably doesnt make any sense at all but this is the closest I got to something that looks like what I understood is needed in the spec. However, when I use this in nodered Im getting a ""Invalid JSONata expression: Key in object structure must evaluate to a string; got: "2022-09-20T07:58:55.000Z"" error message. And now Im completely stuck. Any ideas how to get forward? Thanks for all help and sorry if my post is messy. /N

I take it you want to plot two lines, outdoor and logged? If so then the jsonata would be ( $lines := ["outdoortemperature","loggedoutdoortemp"]; [ { "series": $lines, "data":[ $lines.[($key := $; $$.payload.{"x": $.time, "y": $lookup($, $key)} )] ], "labels":[] } ] )

You could probably adapt this dynamic routine with little ease... [image] Dynamic series identification from message, send data to Chart Dashboard So, i am not 100% certain what you are after but if (by the title "dynamic series") you mean sending alternative types of data from a database (i.e. varying fields and varying quantities) then this should get you close. It was a simple adaption of the previous solution I pointed you to, modified to build the series from the field names of the 1st data element in the data passed in. There are 2 injects to simulate two different sets of mySQL data [image] [i1GL9BSOWR] [{"id":"227e8b13.87c804…

[{ "series": [""], "labels": [""], "data": [[payload.{ "x": datetime, "y": $."m" }]] }] this works for me.

[image] smanjunath211: this works for me. Hi, yeah, that gave me a list of the timestamps. Not sure I follow "where" to add the rest of the data though (temperatures)

YES! Fantastic! Thank you very much, worked like a charm!

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Problem getting data from mysql db to line chart

General

Steve-Mcl 20 September 2022 13:01 2

You could probably adapt this dynamic routine with little ease...

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Problem getting data from mysql db to line chart

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