Optimize empty filter queries

[slim-bean]

If a query like:

{label="foo"} |= "" or {label="foo"} |~ "" these should be optimized to {label="foo"}

You might ask why would someone do this? When creating a dashboard with a log panel you might want to create a text variable on the dashboard which could be used in the filter expression like so:

{label="foo"} |~ "$searchVar"

If the user leaves this filter blank it ends up sending the query as {label="foo"} |~ ""

[cyriltovena]

We should also support {label="foo"} |~ ".*"

[broferek]

Let's say you have this
{filename="foo.log",platform="$platform",host=~"$host"} |= "ERROR" | pattern "<date> [<thread>][<level>] <class> - <stacktrace>"| $search
And you want to filter your search on the labels created by pattern such as class="bar"

It only works when the search is not empty but when you enter in the Grafana dashboard, it is empty and the query fails.

@slim-bean is there any way to get it working ?

[gabzim]

It only works when the search is not empty but when you enter in the Grafana dashboard, it is empty and the query fails.

I've been struggling with this. I use a | json | field=$var and I need a way to say if $var is empty, don't filter at all, otherwise do filter on the label "field" that was added by the json step