There is an error handling issue

kenaflow
#1

If I call

$Cc = (Invoke-KFTemplate -item $a -template $item["Cc"] -LocalConfig $Wildcards -ThrowErrors:$false -ErrorAction SilentlyContinue)

and the “Cc” is empty the workflow breaks but I told the command to SilentlyContinue and throw no errors. Mistake or little but?

#2

Markus,

did you get an exception in Debug mode or during automatic execution?

We have tested this. You get an error like this:

26832   exe3  0016  2019-02-04-21-40-31  Error       Message:

PowerShell error:
    Cannot bind argument to parameter 'Template' because it is null.

No Error Details.

Invocation Info:
      Text: System.Management.Automation.InvocationInfo
      Line: $Cc = (Invoke-KFTemplate -item $a -template $item["Cc"] -LocalConfig $Wildcards -ThrowErrors:$false -ErrorAction SilentlyContinue)

       Col: 45
    Script: C:\Source\wfengine\_workflows\empty-template-test\Workflow Script.ps1


Script Stack Trace:
    at <ScriptBlock>, C:\Source\wfengine\_workflows\empty-template-test\Workflow Script.ps1: line 5
    at <ScriptBlock>, <No file>: line 8

Error Id: ParameterArgumentValidationErrorNullNotAllowed,kenaflow.Cmdlets.InvokeKFTemplate

Stack Trace: **empty**

Inner Exception
    Message:
    Cannot bind argument to parameter 'Template' because it is null.

    Stack Trace: **empty**

This is not an error that kenaflow can handle. It’s a pure PowerShell error. -ErrorAction (PowerShell) and -ThrowErrors are not able to catch this error.

The reason is that the -Template parameter of cmdlet Invoke-KFTemplate is $null. PowerShell (not kenaflow) cannot bind the $null value the the mandatory parameter -Template.

In our understanding it’s an error to pass an empty template into the template engine.

In this default cmdlet you get the same result when you pass in an $null value as parameter:

get-content -Path $null -ErrorAction SilentlyContinue

It makes no sense to read content from a file that is not specified. -ErrorAction does not work here eighter.

#3

We think about using “AllowEmptyString” and “AllowNull” as attributes for the mandatory parameter -Template of Invoke-KFTemplate.

You will get it in version 2.0.29.

#4

Many thanks for the detailed answer … and for the new feature, which makes things easier.

Alternatively, I had experimented with an IF condition, which would have worked, but I use it quite often.

if($item['Cc'] -ne $null) {
  $Cc = (Invoke-KFTemplate -item $a -template $item["Cc"] -LocalConfig $Wildcards -ThrowErrors:$false -ErrorAction SilentlyContinue)
} else {
  $Cc = ""
}