undefined being thrown while redrawing with plotly_selecting

[nicolaskruchten]

Crossfiltering works great with plotly_selecting except that I had to add some catch(function(){}) to suppress errors I was seeing. https://github.com/plotly/plotly.js-crossfilter.js/commit/c48b5beaf1eafbb4c5f68a1923084607c61591c5

Would be great to not have to catch-and-drop undefined.

here's the error I was seeing, sorry for the minification:

Uncaught (in promise) undefined
Promise.then (async)
r.redraw @ plotly-latest.min.js:7
t @ plotly-latest.min.js:7
redraw @ script.js:68
hist_im_select @ script.js:120
n.emit @ plotly-latest.min.js:7
t.emit @ plotly-latest.min.js:7
(anonymous) @ plotly-latest.min.js:7
l @ plotly-latest.min.js:7
r.throttle @ plotly-latest.min.js:7
i.moveFn @ plotly-latest.min.js:7
M @ plotly-latest.min.js:7

[alexcjohnson]

I suspect it's this:

plotly.js/src/plot_api/plot_api.js

Lines 139 to 145 in fb75158

	// if the user is trying to drag the axes, allow new data and layout
	// to come in but don't allow a replot.
	if(gd._dragging && !gd._transitioning) {
	// signal to drag handler that after everything else is done
	// we need to replot, because something has changed
	gd._replotPending = true;
	return Promise.reject();

Are you adding/deleting traces to the same plot that the selection is happening on? I guess we're rejecting here because the plot hasn't actually redrawn yet, so if you expected to be able to do something like look at gd.data or the DOM, it would not be in the correct state. We should at least add a message to the rejection stating the reason. Alternatively, since we're not rejecting due to an error but just due to the plot not being done yet, we could imagine returning a promise that only resolves when the plot is done... wouldn't affect your usage but I worry that this could potentially deadlock existing apps. Dunno quite how it would work but some combination of event bindings that mean two plots are simultaneously waiting for each other to finish?

[nicolaskruchten]

Yes, I'm adding/removing to the same chart that's being dragged on, so as to colour them. Maybe I should restyle?

I should add that the error message is kinda gross, throwing undefined... Is this normal on Promise.reject() ?

[alexcjohnson]

Yes, I'm adding/removing to the same chart that's being dragged on, so as to colour them. Maybe I should restyle?

Your restyle would need to change an array attribute, so it doesn't make any difference, it would go through the Plotly.plot pathway and get rejected here as well. Best would be to see if you could avoid this altogether, and get the updates on the same chart to be handled just by selected.marker.color and unselected.marker.color.

I should add that the error message is kinda gross, throwing undefined... Is this normal on Promise.reject() ?

Hence my comment "We should at least add a message to the rejection stating the reason"

[nicolaskruchten]

I see. +1 to rejecting with a string if possible! I should note that this does work, it just also throws while it's working so maybe I could have the thing wait to redraw until it's done redrawing?

Re selected.marker.color I don't think that will work because the colour I want is dependent not only on the selection-state in the given chart but all the others...

[alexcjohnson]

I should note that this does work, it just also throws while it's working so maybe I could have the thing wait to redraw until it's done redrawing?

The problem is not that it's in the middle of redrawing, it's that it's in the middle of dragging, and we defer redraws until you're done dragging. This is for like streaming data, we stop redrawing the stream while you drag (to select, zoom, pan, whatever). Maybe we shouldn't do that, we should allow redraws mid-drag, but that's a substantially bigger development effort.

Re selected.marker.color I don't think that will work because the colour I want is dependent not only on the selection-state in the given chart but all the others...

Couldn't you have one trace that's "selected elsewhere" and another trace that's "deselected elsewhere", and then use [de]selected.marker.color to automatically bifurcate both of those traces on [de]selected here?

[nicolaskruchten]

Ah I see!

[etpinard]

Merged into #3305