Function to Get Value from Registry - 2 issues: DWORD, console error

Question

This is ma very simple PowerShell function to get reg value from registry:

Function GetRegKey {
    Param([String]$GetRegKeyPath, $GetRegKeyName)
    If (Test-Path -Path $GetRegKeyPath) {
        If (Get-ItemProperty -Path $GetRegKeyPath -Name $GetRegKeyName) {
            $GetRegKeyVal = (Get-ItemPropertyValue $GetRegKeyPath $GetRegKeyName)
            Return $GetRegKeyVal
        } Else {
            write-output ("Warning! Path:  '$GetRegKeyPath'  is exist, but RegKey:  '$GetRegKeyName'  is:  not exist.") }           
    } Else {
        write-output ("Warning! Path:  '$GetRegKeyPath'  is not exist!")
        Return $null }
}

Example:
GetRegKey "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion" "ProgramFilesDir"
will give output like: C:\Program Files

I have two things what is not working:

1. If $GetRegKeyName is not exist script besides go to command write-output ("Warning! Path: '$GetRegKeyPath' is exist, but RegKey: '$GetRegKeyName' is: not exist.") is also display in console error:

Is this can be somehow avoid? I did try with pipe | Out-Null but its bassically not a solution I guess.

2. Second thing what is not works here is reg with DWORD value. Is command Get-ItemProperty -Path $GetRegKeyPath -Name $GetRegKeyName can't be used with DWORD?

Answer 1

I suggest streamlining your function as follows, which only requires a single Get-ItemPropertyValue (note that I've renamed the function to GetRegValue, because it is a registry value's (data) that is returned):

Function GetRegValue {
  Param(
    [Parameter(Mandatory)]
    [String] $KeyPath, 
    [Parameter(Mandatory)]
    [String] $ValueName
  )

  try {
    Get-ItemPropertyValue -ErrorAction Stop $KeyPath $ValueName
  }
  catch [System.Management.Automation.ItemNotFoundException] {
    Write-Warning "Path:  '$KeyPath'  does not exist."
  }
  catch [System.Management.Automation.PSArgumentException] {
    Write-Warning "Path:  '$KeyPath' exists, but RegKey:  '$ValueName'  doesn't." 
  }

}  

• A try / catch statement is used to match errors by their exception type, from which the specific error condition can be inferred.

  • Note that any exception type not matched would result in a script-terminating error; that is, error conditions other than the matched ones cause a fatal error (by default), such as a lack of permissions.

• The common -ErrorAction parameter is used with Stop in order to promote non-terminating errors to (script-)terminating ones, which allows them to be caught with try / catch.

  • As an aside: Due to a longstanding bug still present as of PowerShell 7.3.1, Get-ItemPropertyValue inappropriately reports a (statement-)terminating error when the key path exists, but not the value name - see GitHub issue #5906.

• Write-Warning is used to emit the warnings, which uses the dedicated warning output stream, which is conceptually preferable and also gives you automatic coloring of the message.

---

As for DWORD values:

PowerShell is capable of returning types of all data stored in the registry (they get mapped onto equivalent .NET types), so there shouldn't be a problem with REG_DWORD registry values.

You can verify by calling the function above as follows:

GetRegValue  HKCU:\Console FontSize

This should output an [int] (System.Int32) value such as 1048576.

Note that if the value is too large to fit into [int], you'll get a [uint32] (System.UInt32) value instead.