When selecting a metric that has no data the Dashboard shows the previous data (histogramList[0] is undefined)

[chutten]

In the event that a metric has no data to show (like Nightly 66's DEVTOOLS_FLEXBOX_HIGHLIGHTER_TIME_ACTIVE_SECONDS when "sanitize data" is true), then we error to the log

TypeError: histogramsList[0] is undefined[Learn More] dist.js:813:11
	displayHistograms https://telemetry.mozilla.org/new-pipeline/src/dist.js:813
	<anonymous> https://telemetry.mozilla.org/new-pipeline/src/dist.js:380
dispatch7jQuery	gFilterChangeTimeout https://telemetry.mozilla.org/new-pipeline/src/dist.js:347
	calculateHistograms https://telemetry.mozilla.org/new-pipeline/src/dist.js:570
	updateDateRange https://telemetry.mozilla.org/new-pipeline/src/dist.js:648
	calculateHistograms https://telemetry.mozilla.org/new-pipeline/src/dist.js:568
	Telemetry_getEvolution https://telemetry.mozilla.org/v2/telemetry.js:569
	populateEntriesMap https://telemetry.mozilla.org/v2/telemetry.js:498
	onload https://telemetry.mozilla.org/v2/telemetry.js:380

And the view remains on the previous data, whatever it was. We -do- have the ability to show "no data for these options" views via metricsgraphics, so we should probably do that instead of silently throwing a fit.

[hardik25]

@chutten

I would like to work on this issue. From initial triaging, I could locate the part of code which will display the "no data" message. Below is the part of code that I found in the function displaySingleHistogramSet in dist.js:

telemetry-dashboard/new-pipeline/src/dist.js

Line 1065 in 7d7c4a0

if (histograms.length === 0) {

Could you please confirm if I am on the right track?

Also, how could I test my fixes?

Thanks!

[chutten]

Sorry for the delay, I was out for the week.

Yes, that is exactly the "no data" message we hope to trigger! You can test your fix by loading the Measurement Dashboard and choosing DEVTOOLS_FLEXBOX_HIGHLIGHTER_TIME_ACTIVE_SECONDS as the metric you'd like to display. Check the devtools console for a TypeError. If there is one, the problem persists.

[chutten]

Unassigning due to inactivity.