Explicitly setting tickmode to array disables tickvals in date axis

[nicolaskruchten]

Initially reported in plotly/plotly.py#2478

This codepen is a bit puzzling: https://codepen.io/nicolaskruchten/pen/MWaZBwa ... I'm explicitly setting tickmode to array and seeing the default tick labels. But if I comment out that tickmode line it does the right thing, even though the schema docs say that this configuration should imply tickmode=array!

[archmoj]

Not sure if this should be labeled as a bug; whereas we have this logic:

plotly.js/src/plots/cartesian/tick_value_defaults.js

Lines 27 to 29 in 0b54b3f

	if(_tickmode === 'array' &&
	(axType === 'log' || axType === 'date')) {
	tickmode = containerOut.tickmode = 'auto';

[nicolaskruchten]

And yet we say: "(*array* is the default value if tickvals is provided)" in https://github.com/plotly/plotly.js/blob/master/src/plots/cartesian/layout_attributes.js#L378

So what is the actual value of tickmode for date axes when tickvals is provided and tickmode is not provided? Because that does display the desired behaviour :)

[archmoj]

So what is the actual value of tickmode for date axes when tickvals is provided and tickmode is not provided? Because that does display the desired behaviour :)

tickmode would be set to array in that case.

[archmoj]

The logic was present since v1.0:

It looks like a bug to me.

[nicolaskruchten]

Weird! So if I don't set it, it gets set to array but it skips this check?

[archmoj]

Weird! So if I don't set it, it gets set to array but it skips this check?

Positive. I think we could/shoud fix this for log as well.
I am close to open a PR for this.