convert string array to string in hashtable to export to CSV

i have the following code , is output the RSOP XML value to CSV:

$a=@{
'name' =$xmldoc.rsop.ComputerResults.ExtensionData.Extension.SecurityOptions.Display |
Where {$_.Name -eq "Interactive logon: Message text for users attempting to log on" }|  Select -expand  "DisplayStrings"  | Select -expand Value

}

$a |export-CSV b.csv

as expected, the output not what i wanted,it output systemobject[] .

I tried to join the string, but failed

......
'Name'=$xmldoc.rsop.ComputerResults.ExtensionData.Extension.SecurityOptions.Display |
Where {$_.Name -eq "Interactive logon: Message text for users attempting to log on" }|  Select -expand  "DisplayStrings"  | Select -expand Value, @{Name='DisplayStrings';Expression={[string]::join(“;”, ($_.DisplayStrings))}}  

..........

I cant use psobject method due to my production environment security rules, Any help will be appreciated.

See the properties of the return object, that will help you to retrieve the required values.

[pre]$a | Get-Member[/pre]

As far as my understanding $a.name needs to be exported…

[pre]$a.name | Export-Csv b.csv[/pre]

… | Select -expand Value

It depends on what is in Value property. If its an object, then string conversion(which happens internally) displays it to system.object.

Try an out-String at the end.

… | Select -expand Value | Out-String