Question

I’m writing a script that has a lot of strings that need to be output either to a log or to the screen. To help simplify maintenance, I created a very simple lang.xml file where I store the strings. A lot of the strings display information that’s held in variables in the script, so I wrote a little cmdlet that will expand the strings in returned xml #text nodes.

This works pretty great up until I use this in catch block to format error messages. When I attempt to expand the Exception message, for example, an empty string is returned. Even when I pass the Exception object to the cmdlet it expands to an empty string. Below is a snippet of XML and the cmdlet, with example output.

Sample XML:

<?xml version="1.0" ?>
  <lang>
    <keyword name="ERRMessage">
      <string>"Error message: $($Exception.Exception.Message)"</string>
    </keyword>
  </lang>
</xml>

Cmdlet:

function Read-Lang
{
  [CmdletBinding()]
  param(
    [Parameter( Mandatory=$true,
                ValueFromPipeline=$true,
                ValueFromPipelineByPropertyName=$true,
                HelpMessage="The name atttribute of a keyword in lang.xml")]
    [string[]] $Keyword,
    $Exception
  )

  begin
  {
    if ( $global:LangXML -eq $null )
    {
      Write-Debug "Language XML has not been loaded, loading now."
      $global:LangXML = [xml] (Get-Content '.\lang.xml')
    }
  }

  process
  {
    foreach ( $name in $Keyword)
    {
      $Query = "/lang/keyword[@name=`"$name`"]/string"
      $global:LangXML.SelectNodes($Query) | 
        ForEach-Object { $ExecutionContext.InvokeCommand.ExpandString($_."#text") }       
    }
  }
}

Example:

try { get-content goo -ErrorAction Stop} catch { Read-Lang -KeyWord 'ERRMessage'  -Exception $_ }

Expected output:

Error Message: Cannot find path 'path\to\goo' because it does not exist.

Actual output:

Error Message:

Answer 1

I’ve tested you code with xml example.

It works for me, after I removed the </xml> closing tag in lang.xml file, that gives me error here

$global:LangXML = [xml] (Get-Content '.\lang.xml')

this what I got:

PS C:\ps> try { get-content goo -ErrorAction Stop} catch { Read-Lang -KeyWord 'ERRMessage'  -Exception $_ }
Error message: Impossibile trovare il percorso 'C:\ps\goo' perché non esiste.
PS C:\ps>

p.s.: error is in italian, I’m on it-it culture system but is the right error.