$__contains macro doesn't expand correctly with variable of type custom

[tjmoore]

I have an application logging custom events with Application Insights and have Grafana (self hosted, v5.3.4) set up with Application Insights data source. I have a multi-value variable defined as $room on the dashboard as a custom type with the following value:

Room 1, Room 2, Room 3, Room 4

I then have a query such as (simplified for example):

customEvents
| where $__contains(customDimensions.roomName, $room)
| project customDimensions.start, customDimensions.roomName

Query inspector shows the query parameter for the API call expands out to:

customEvents
| where customDimensions.roomName in ({Room 1,Room 2,Room 3,Room 4})
| project customDimensions.start, customDimensions.roomName

This is invalid according to Log Analytics query in Azure Portal. One reason I can see is the values are not quoted.

So if I change the variable to use quotes: 'Room 1', 'Room 2', 'Room 3', 'Room 4' (not ideal as it shows the quotes in the drop down in dashboard).

This expands to:

customEvents
| where customDimensions.roomName in ({'Room 1','Room 2','Room 3','Room 4'})
| project customDimensions.start, customDimensions.roomName

This is also invalid: Query could not be parsed at '{' on line [2,38]

If I remove the { and } in Azure Portal query, then it runs fine.

It appears to be broken and doesn't correspond to the documentation:

$__contains(colName, $myVar) - is to be used with multi-value template variables. If $myVar has the value 'value1','value2', it expands to: colName in ('value1','value2').

p.s. The custom variable I'm just using at the moment to hard code a set of values. I'm having a hard time trying to get a variable to pick values from a query. I just get an error "Template variables could not be initialized: undefined" whatever query I use.

[tjmoore]

I think the problem here is with the variable definition in Grafana rather than the macro. Using the custom variable type specifying a series of comma separated values, the variable has { and } surrounding it. Also it doesn't put quotes around the values, but manually adding quotes makes the quotes appear in the selection drop down in the UI also.

[tjmoore]

I've found a workaround using trims and a split. The trims to remove { and }, and the split to convert the comma separated string into an array.

let rooms = split(trim("}", trim("{", "$room")), ",");
customEvents
| where $__contains(customDimensions.roomName, rooms)
| project customDimensions.start, customDimensions.roomName

[tjmoore]

Okay, I realise now why the brackets pass through. Having read the right bit of the documentation, I need to use "${room:csv}" to produce a comma separated list without the brackets. Still, $__contains macro needs the list as an array object it seems so have to do:

let rooms = split("${room:csv}", ",")

At the least, this is a documentation issue, as currently the Azure Monitor plugin page says:

$__contains(colName, $myVar) - is to be used with multi-value template variables. If $myVar has the value 'value1','value2', it expands to: colName in ('value1','value2').

which doesn't work.