Charts Empty States

[gvnmagni]

We are currently missing a consistent and unified way of dealing with empty states for charts.

This topic could be bigger or smaller according to our desire to be more or less precise in communicating to the user what is happening and why no information are displayed on a specific chart. There is a little border between overwhelming the user with information and inform users in a quick and simple way.

The most important thing to keep in mind is that this is not a black or white case, we might find ourselves in very different contexts according to the amount of information about both the data series that should be displayed and their domains.

Let's use XY charts as an example and let's also assume for a second that we don't have any document in the specified timerange which is the base to start talking about empty states. We have these few cases:

1. Both X and Y domains are defined
2. Only X domain is defined and we have no clue about Y domain
3. Only Y domain is defined and we have no clue about X domain
4. We don't have any clue about X and Y domains

I see two approaches:

1. Being precise and display even just partial information that could be available within data. I am talking about having only X or Y domain, being transparent with user and trying to communicate them everything we got from data
2. Being a little more "high-level" and in all cases just tell users that we don't have results.

I personally prefer option 1, given the complexity of our product and the skills of a group of users I feel confident that we should share as much as possible to users so that they could be aware of the context and act accordingly.

A preliminary exploration has been done in this direction (as shown in the following image) in order to design all the possible variety of contexts that we might encounter. For each major typology of charts... I am attaching this image as an example but the exploration is bigger and covers more cases, please feel free to reach out to me to get access.

(colors in this image are darker than expected, just to make it more visible)

[gvnmagni]

Link to issue elastic/kibana#177100