Error on hover event of parallel coordinates graph component

[masdeseiscaracteres]

I am trying to associate a callback to the hover event in a parallel coordinates plot, but it does not seem to work properly. More specifically, it raises the following JS error in my Dev Console:

Any clue?

[chriddyp]

Thanks for reporting! I'll check in with https://github.com/plotly/plotly.js to see what might be the issue.

[chriddyp]

It looks like the parcoords handles events a little bit differently than the rest of the plots. We'll have to make a patch for this in the Graph component.

Thanks for reporting!

[chriddyp]

If community member would like to contribute, here is a sketch of the problem and solution:

1. The issue seems to be that the event data that parcoords emits isn't like the rest of the traces. The point data is a single object instead of a list of objects, see here: https://github.com/plotly/plotly.js/blob/c842e992bf963c57401754c2f01a9c7927596173/src/traces/parcoords/parcoords.js#L325-L332
2. Our code expects that points is an array, see here: https://github.com/plotly/dash-core-components/blob/master/src/components/Graph.react.js#L24
3. We would need to modify points so that if it isn't an array (if it is a single object), then make it an array like the rest of the points. something like:

if (R.type(eventData.points) === 'object') {
    eventData.points = [eventData.points];
}

Where R refers to the ramda library: http://ramdajs.com/docs/#type

4. Then, we would need to manually test that this works. We should also verify this with the sankey diagram type as it was developed at the same time as parcoords and might have idiosyncratic behaviour as well. Unfortunately, our integration tests do not cover events (yet), so we need to just test this manually. A manual test case can follow the example outlined here: https://plot.ly/dash/interactive-graphing