Chart.js: New Chart extending BAR chart doesn't work

[stockiNail]

Expected Behavior

In the version 2.8.0, creating new chart extending a bar chart, it works.
See the code:

Chart.defaults.derivedBar = Chart.defaults.bar;
var custom = Chart.controllers.bar.extend({
   draw: function(ease) {
          Chart.controllers.bar.prototype.draw.call(this, ease);
   }
});
Chart.controllers.derivedBar = custom;

var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
    type: 'derivedBar',
    data: {
        labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
        datasets: [{
            label: '# of Votes',
            data: [12, 19, 3, 5, 2, 3]
        }]
    }
});

Current Behavior

In the new vesion 2.9.1, new chart is not rendered and completely empty (without any message into log)

The problem is ONLY for BAR chart (at least on my tests).

Environment

• Chart.js version: 2.9.1
• Browser name and version: FF 70.0

[benmccann]

@stockiNail I'm guessing you also need the dataset defaults, which were introduced in 2.9. There's some info in the docs and you can see it being done in the current bar controller source. The reason for this is to better support mixed charts

[stockiNail]

@benmccann Thank you! It works. A hint, if I may. In the doc, about Controllers, I don't find (but I'm getting old and maybe there is....) something like that:

Chart.defaults.global.datasets.derivedBar = Chart.defaults.global.datasets.bar;

[stockiNail]

@benmccann honestly in another issue I asked for that (without feedback) what you suggested.

See issue #6482

Thanks a lot!