select-string only the "description" from XML output?

I run the following command to process a database/and its partitions.

Invoke-ASCmd InputFile $file -Server $Server >$output

from the output, if there is an error, this is whats displayed:

<return xmlns="urn:schemas-microsoft-com:xml-analysis"><root xmlns="urn:schemas-microsoft-com:xml-analysis:empty"><Excep
tion xmlns="urn:schemas-microsoft-com:xml-analysis:exception" /><Messages xmlns="urn:schemas-microsoft-com:xml-analysis:
exception"><Error ErrorCode="-1055653884" Description="Either the dimension with the ID of '0f585685' does not exist in the database with the ID of '', or the u
ser does not have permissions to access the object." Source="Microsoft SQL Server 2017 Analysis Services" HelpFile="" />
</Messages></root></return>

can i extract the description part since its the most useful?

i want to extract it to have meaningful email messages with errors that can be understood right away without having to search through the whole other XML mess

$Email_Body = Get-Content -Path $output | Out-String

essentially, the email would have:

Either the dimension with the ID of '0f585685' does not exist in the database with the ID of '', or the u ser does not have permissions to access the object.
also some outputs sometimes contain multiple errors/descriptions.

how would i handle that?

for example:

<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="-1055784933" Description="[Teradata Database] [8017] The UserId, Password or Account is invalid.. The exception was raised by the IDbConnection interface." Source="Microsoft SQL Server 2017 Analysis Services" HelpFile="" /><Error ErrorCode="-1055784860" Description="A connection could not be made to the data source with the DataSourceID of '', Name of 'Teradata '." Source="Microsoft SQL Server 2017 Analysis Services" HelpFile="" />

can all descriptions be stored as part of $Email_body and sent? so in this case, it would be:

[Teradata Database] [8017] The UserId, Password or Account is invalid.. The exception was raised by the IDbConnection interface.

A connection could not be made to the data source with the DataSourceID of ‘’, Name of 'Teradata '.

Assuming you save the error as $msg, you need to convert it to an XML type:

[xml]$xml = $msg

then you can use . (dot) notation to get the details when it’s converted to XML:

$xml.return.root.messages.error.Description

Select-String really should not be used for XML parsing. You can, just as you could using RegEx matching.

$XmlData = @'
< return xmlns="urn:schemas-microsoft-com:xml-analysis">< root xmlns="urn:schemas-microsoft-com:xml-analysis:empty">< Excep
tion xmlns="urn:schemas-microsoft-com:xml-analysis:exception" />< Messages xmlns="urn:schemas-microsoft-com:xml-analysis:
exception">< Error ErrorCode="-1055653884" Description="Either the dimension with the ID of '0f585685' does not exist in the database with the ID of '', or the u
ser does not have permissions to access the object." Source="Microsoft SQL Server 2017 Analysis Services" HelpFile="" />
Messages>root>return>
'@ 

[RegEx]::Matches($XmlData,'(?<=Description=)(?s)(.*)(\.")').Value

# Results

"Either the dimension with the ID of '0f585685' does not exist in the database with the ID of '', or the u
ser does not have permissions to access the object."

However, this why the xml cmdlets exists as well as additional modules on the MS PowerShellGallery.
Well, as long as the XML is properly formatted.

Get-Command -Name '*xml*' | Format-Table -AutoSize

CommandType Name                      Version     Source
----------- ----                      -------     ------
Function    ConvertFrom-PSFClixml     0.10.28.144 PSFramework
Function    ConvertFrom-PSFClixml     0.10.27.135 PSFramework
Function    ConvertTo-PSFClixml       0.10.28.144 PSFramework
Function    ConvertTo-PSFClixml       0.10.27.135 PSFramework
Function    Export-PSFClixml          0.10.28.144 PSFramework
Function    Export-PSFClixml          0.10.27.135 PSFramework
Function    Export-PSFClixml          0.9.25.113  PSFramework
Function    Get-ClusterFaultDomainXML 2.0.0.0     FailoverClusters
Function    Import-PSFClixml          0.10.28.144 PSFramework
Function    Import-PSFClixml          0.10.27.135 PSFramework
Function    Import-PSFClixml          0.9.25.113  PSFramework
Function    Set-ClusterFaultDomainXML 2.0.0.0     FailoverClusters
Cmdlet      ConvertTo-Xml             3.1.0.0     Microsoft.PowerShell.Utility
Cmdlet      Convert-XMLtoJSON         5.0.0.1     Sorlov.PowerShell
Cmdlet      Export-Clixml             3.1.0.0     Microsoft.PowerShell.Utility
Cmdlet      Import-Clixml             3.1.0.0     Microsoft.PowerShell.Utility
Cmdlet      Merge-XMLFile             5.0.0.1     Sorlov.PowerShell
Cmdlet      New-XSDfromXML            5.0.0.1     Sorlov.PowerShell
Cmdlet      Select-Xml                3.1.0.0     Microsoft.PowerShell.Utility

Just read in the XML and select the value you are after.

Select-Xml Module:Microsoft.PowerShell.Utility Finds text in an XML string or document https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/select-xml?view=powershell-6

Search XML files with PowerShell using Select-XML
https://www.petri.com/search-xml-files-powershell-using-select-xml

As far as the email part. This is what Send-MailMessage is for. Capture what you need in a variable or variables, and pass that to it.

# get function / cmdlet details
(Get-Command -Name Send-MailMessage).Parameters
Get-help -Name Send-MailMessage -Full
Get-help -Name Send-MailMessage -Online
Get-help -Name Send-MailMessage -Examples

Excellent, thank you both!