Curly brackets in variables

Question

Hi guys, here' my problem:
Get-DhcpServerv4OptionValue -ScopeId 172.19.1.0 -all -OptionId 132 | Set-DhcpServerv4OptionValue -ScopeId 172.19.2.0 -Value {0x35, 0x35, 0x32}
work just fine from the powershell prompt.
Import-Csv .\Nodi.csv -Delimiter ";" | foreach {
    if ($_.Value -ne "-") {
        Get-DhcpServerv4OptionValue -ScopeId 172.19.1.0 -all -OptionId 132 | Set-DhcpServerv4OptionValue -ScopeId $_.ScopeID -Value $_.Value
Doesn't work: 
Set-DhcpServerv4OptionValue : Parameters for option value to be set for option ID 132 do not match with option definition on DHCP server SAGA.
At C:\dhcpscripts\Set-ScopeOption43.ps1:6 char:78
+         Get-DhcpServerv4OptionValue -ScopeId 172.19.1.0 -all -OptionId 132 | Set ...
+                                                                        
     ~~~
    + CategoryInfo          : InvalidArgument: (132:root/Microsoft/...erv4OptionValue) [Set-DhcpServerv4OptionValue], CimException
    + FullyQualifiedErrorId : WIN32 87,Set-DhcpServerv4OptionValue
CSV contents:
ScopeId,Value
172.19.2.0,{0x35, 0x35, 0x32}
172.19.3.0,{0x35, 0x35, 0x33}
172.19.4.0,{0x35, 0x35, 0x34}
If I change, in the script, $_.Value with, for example, {0x35, 0x35, 0x32} it works. The problem is passing the value from the CSV file. When inserting Write-Host $_.Value in the script, it display the values correctly with curly brackets.
Any suggestion?
Dario Palermo

Answer 1

Couple of things to note here:
The -Value parameter of the Set-DhcpServer4OptionValue cmdlet accepts an array of strings.
When you type something in curly braces in a PowerShell script (if it's not in quotation marks), you're typically defining a ScriptBlock object.  The literal syntax for these is { <Statements> }.
When you import a CSV file, you're getting strings.  Strings that happen to contain curly braces are still just strings.
When you convert a ScriptBlock object into a string, the curly braces are not included in the string output; only the statements inside it.
Your Import-Csv command mentions a delimiter of ";", but your sample CSV contents have separated the ScopeId and Value fields with commas.  I assume that this was meant to be a semicolon, but commas within the curly braces. 
Is this correct? 
With this in mind, when you run the command locally with -Value { 0x01, 0x02, 0x03 } , what PowerShell is really passing to the command is a string value of " 0x01, 0x02, 0x03 "; the ScriptBlock literal you wrote is converted directly to a string
for you.  If you ran the command with -Value "{ 0x01, 0x02, 0x03 }", you'd probably get the same error that you're seeing during the CSV import.
In order to make this work, you'll need to strip out the curly braces from the CSV data (either directly in the file, or at the time of import; doesn't matter), before calling Set-DhcpServer4OptionValue. Try this:
Import-Csv .\Nodi.csv -Delimiter ";" | foreach {
if ($_.Value -ne "-") {
$value = $_.Value -replace '^\s*{\s*|\s*}\s*$'
Get-DhcpServerv4OptionValue -ScopeId 172.19.1.0 -all -OptionId 132 |
Set-DhcpServerv4OptionValue -ScopeId $_.ScopeID -Value $value
This removes the curly braces (and any leading / trailing whitespace, for good measure) from the input data before passing the string on to Set-DhcpServer4OptionValue.