Creating bar chart from variables

General
1

Hello

I am trying to create a bar chart in nodered. I have a function which every 60 seconds, adds to an existing variable. At midnight every night, the variable is reset to 0.

For example,
at 0:00 - value = 0
at 0:01 - value = 5
at 0:02 - value = 8
... eventually resetting back to 0 at 0:00.

The process then repeats itself.

I need to plot a bar for each 24 hour period, updated every 60 seconds with the revised value. Then after midnight, a new bar is created and the old bar is left where it is.

I can handle the timers, variable increasing etc. I'm just not sure how to get this data into the chart dynamically.

I have read that the bar chart accepts a payload as follows:

[{
    "series": [ "X" ],
    "data": [ [5,6,9] ],
    "labels": [ "Mon", "Tue", "Wed" ]
}]

In my case, a new data number and label would need to be created every 24 hours. If this were an array I would be able to do it, but I don't think it is? What is the least painful way to update the payload to the chart dynamically as described above?

2

If your existing variable was an object

let myobject = {"Mon": 0, "Tue": 8, "Wed": 55, "Thu": 0, "Fri": 11, "Sat": 9, "Sun": 3}

Note myobject begins with "Mon", that's what will appear first on the chart.

Then you could pass it to your chart like this

msg.payload = 
[{
    "series": [ "X" ],
    "data": [ Object.values(myobject) ],
    "labels": Object.keys(myobject)
}]

And to update today's value

const days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]  
const today = days[new Date().getDay()]  // getDay() returns 0 to 6, 0 is Sun

myobject[today] = 99

That's not going to work, your bar chart will show 0 for every day but today.
You will need a strategy for clearing down the values, perhaps after 7 days.

But that's all for Dashboard 1. Do you have plans to migrate to the new dashboard?

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