In azure workbook, how to handle an unset parameter so that it doesnt lead to syntax errors in subsequent query in the dasboard

Question

The query for displaying the table in azure workbook works fine if a parameter {ServiceName} is set, however it displays an error if the parameter is unset (because of dependency on another parameter value which doesn't fetch data) and passed as an empty value. the query throws a syntax error

"Query could not be parsed at ')' on line [10,22] Token: ')' Line: 10 Postion: 22"

, please suggest a way in which the empty/unset parameter can be handled and a default message can be displayed instead of an error

let endDateTime = {timeRange:end};
let startDateTime = {timeRange:start};
KubeEvents
| where TimeGenerated >= startDateTime
| where TimeGenerated < endDateTime
|extend ServiceName = split(Name, "-")[0]
|where ServiceName in ({ServiceName})
|extend PodName=Name
|where Namespace in ({Namespace})
|where ObjectKind in ('Pod')
|project TimeGenerated, ObjectKind,Namespace,ClusterName, ServiceName,PodName, Reason,Message,FirstSeen,LastSeen,Count
| summarize arg_max(TimeGenerated, *) by PodName

Answer 1

Hi, Basically you can use KQL to check if the parameter is empty or not and have different condition based on that. I do not have the full details of your workbook nor your data from Log Analytics but the query should look something like the one below where only one line is modified. You may need some small editing if it does not work right away in your case.

let endDateTime = {timeRange:end};
let startDateTime = {timeRange:start};
KubeEvents
| where TimeGenerated >= startDateTime
| where TimeGenerated < endDateTime
|extend ServiceName = split(Name, "-")[0]
| where isempty('{ServiceName}') or (ServiceName in ('{ServiceName}'))
|extend PodName=Name
|where Namespace in ({Namespace})
|where ObjectKind in ('Pod')
|project TimeGenerated, ObjectKind,Namespace,ClusterName, ServiceName,PodName, Reason,Message,FirstSeen,LastSeen,Count
| summarize arg_max(TimeGenerated, *) by PodName

Update Option 2:

Make the parameter required.

On the section for your query Configure advanced settings by checking Make this item conditionally visible with the name of the parameter (Test1 in the screenshot) is not equal to empty value.

Add another section of type Text. Set text style to Error and enter the message you want to appear:

Configure advanced settings and check make this item conditionally visible with the name of the parameter (Test1 in the screenshot) equals to empty value.

That way you will have one section displaying error when the parameter is not configured and another one when it is configured.

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