Apex link

elm-apex-charts-link: a tentative solution to using apex charts within the comfort of elm

Design decisions

the targeted solution

I wanted to get an easy way to "describe" how the charts should look like and defer the transformation from the "graph description" to the actual Apex JSON to a custom encoder.

Right now, the code looks a bit like this. First make define a plot/bar chart/etc with one of the appropriate function:

plot =
    Plot.plot
        |> Plot.addLineSeries "Connections by week" (connectionsByWeek logins)
        |> Plot.addColumnSeries "Connections within office hour for that week" (dayTimeConnectionByWeek logins)
        |> Plot.addColumnSeries "Connections outside office hour for that week" (outsideOfficeHourConnectionByWeek logins)
        |> Plot.withXAxisType Plot.DateTime

Then, transform that definition into an apex chart and customize the appearance:

apexPlot =
    plot
        |> Apex.fromPlotChart
        |> Apex.withColors [ "#ff2E9B", "#3f51b5", "#7700D0" ]

It is still pretty much just a WIP and needs to support more options and more types of charts. Hopefully, this will come in a near future but it is already working fine as it is.

How to plug it

Once we've got a nice chart description what shall we do with it? This package offers 2 ways of plugging your data to an actual chart: via ports or via a custom-elements.

The first options is achieve by providing a JSON encoder for the charts (see Apex.encodeChart).

The second requires to import and setup the npm companion package: elm-apex-charts-link, once you've set it up you can use the Apex.apexChart.

For a complete example, have a look at /example.

ApexCharts' custom element

The second part of this elm-package is actually language/framework agnostic. It is a custom element wrapping the apexcharts library as simply as possible.

To use it, install and import the npm package apexcharts-custom-element and voilà. You should now be able to create a custom-element named apex-chart which will take the apexcharts definition in the chartData property. If your framework/environment does not allow you to work easily with properties, you can instead use the attribute data-chart (with JSON encoding) which will work just the same.