Grafana should not allow empty values for variable selection to avoid template errors

Grafana MSSQL
,
1

I creates few variables which do not include null values, but when I change the variable selection It can be empty values automatically selected then it cause template errors. I use SQL datasource and SQL queries.

When I design variable there should be “Not Null” option and Grafana should automatically prevent Empty selections to avoid this problem.

Steps to reproduce the problem:

  1. Create variables and use them in chart’s query in where condition.
  2. Make selection in variable value’s list. (If you do not use “Include All Option” and use “Multi Value” you can easily uncheck the selection it will be automatically empty value)
  3. After making selections try go back in your browser few times then you will see the empty values.

Version numbers (grafana, prometheus, graphite, plugins, operating system, etc.):
Grafana v7.5.15 (7dd69b2442)

2

Maybe I’m way off but are you filtering a Graph with a SQL Fed Variable

Like this “Variable”

SELECT metric 
FROM Table
GROUP BY metric

Then in the Graph

SELECT time, metric, value
FROM Table
WHERE metric IN ( $metric )
ORDER BY time DESC

I’ve done similar filters but with Nulls/Blanks in Data I’ve had to handle them myself

-- FILTER
SELECT CASE WHEN metric IS NULL OR metric IN ( '',' ' ) 
           THEN 'BLANK' 
           ELSE metric 
           END
FROM Table
GROUP BY metric

-- GRAPH
SELECT time, metric, value
FROM Table
WHERE CASE WHEN metric IS NULL OR metric IN ( '',' ' ) 
           THEN 'BLANK' 
           ELSE metric 
           END IN ( $metric )
ORDER BY time DESC

Hope I’m not way off and it’s some help

2 Likes
3

Do you paid version or OSS?
Does this issues exist in latest version of grafana?

4

I’ve been struggling with this problem for months and I’m so glad I finally found a solution. Thanks!

1 Like