Invoke-ASCmd to return error/warning in PowerShell - powershell

Question

Running the PowerShell in my deployment pipeline:
Write-Host "Invoking deployment script... This may take several minutes."
Invoke-ASCmd -Server:$SsasServer -InputFile $path\$bim.xmla | Out-File $path\$bim.xml
Write-Host "Please check $path\$bim.xml as this is output of this deployment"
I want to take the output file of the Invoke-ASCmd: $bim.xml and determine if a warning exist or error exist. It would be ideal to return a warning messages to the console in my azure pipeline.
Example Warning message:
<return xmlns="urn:schemas-microsoft-com:xml-analysis"><root xmlns="urn:schemas-microsoft-com:xml-analysis:empty"><Exception xmlns="urn:schemas-microsoft-com:xml-analysis:exception" /><Messages xmlns="urn:schemas-microsoft-com:xml-analysis:exception"><Error ErrorCode="-1055784777" Description="The JSON DDL request failed with the following error: Failed to execute XMLA. Error returned: 'The column 'ProcessDateKey' in table 'Financial Measures' has invalid bindings specified.
'.." Source="Microsoft SQL Server 2016 Analysis Services Managed Code Module" HelpFile="" /></Messages></root></return>
I am not sure if this is the correct way to handle this xml exactly. Here is my first draft:
[xml]$XmlDocument = Get-Content -Path $path\$bim.xml
if($XmlDocument.return.root.Messages.Error){
foreach ($errorMessage in $XmlDocument.return.root.Messages.Error ){
$message = $errorMessage.Description
Write-Error $message
}
exit 1
}

Answer 1

You cannot use if directly on the Error node, this could also be an Error collection. I recommend using a xPath query to find all the Error messages.
Also you can get directly the Xml output from Invoke-AsCmd into an xml variable:
[xml]$xmlResult = Invoke-ASCmd -Server:$SsasServer -InputFile $path\$bim.xmla
$errors = $xmlResult.return.root.Messages.SelectNodes("*[name() = 'Error']")
if($errors.Count -gt 0){
foreach ($errorMessage in $errors){
Write-Error $message.Description
}
exit 1
}