Empty result in sub-query fails whole graph

[promd]

Hi.
1st off: Many Thanks for the Plugin - it made great things possible for me !

Right now, I am facing what I believe is a bug - let me give some details:

• I wrote a webservice that collects data and returns CSV formatted data.
• This service returns multiple subsets of the data, but they all have the same columns (some being unpopulated in certain cases)
• I have graphs in Grafana that use multiple of these CSV streams to populate the graf.
• If one (or more) of the queries returns an empty result set (header send always), the whole Graph will go to "No Data in response", although at least one of the queries has valid data to show.

[zoltanbedi]

Can you please maybe attach a csv file that I can use to reproduce this?

[guanzo]

You don't need specific data to reproduce, his instructions are accurate.

First, create a panel with an endpoint that returns any csv data. Just get the panel working.

This working panel can be broken in 2 ways. Create a new panel with an endpoint that either:

1. Returns 0 bytes in the response. Both panels will crash.

2. Returns the CSV headers only, no data rows.

• Before defining the timestamp field, everything still works.
  
  

• Then define a field with type "Time". Both panels crash.
  

2 issues here:

• The panel that receives 0 bytes, or headers with no data rows, should fail gracefully instead of crashing.
• Working panels should not be affected by other panels that crash.

[zoltanbedi]

Thanks for the detailed explanation @guanzo, I was able to reproduce it.