Powershell Select-Object how to get array of values - powershell

Question

I am trying to delete contents of few folders.
What I have:
$Config = #{
InstallPath = 'C:\Program Files\App'
SubPaths = #('www\app1', 'www\app2', 'www\app3')
}
And here is the code to get contents:
$Config.SubPaths | Select-Object { Join-Path $Config.InstallPath $_ } | Get-ChildItem
But it doesn't work, because Get-ChildItem receives object like below:
#{ Join-Path $Config.InstallPath $_ =C:\Program Files\App\www\app1}
Error:
Get-ChildItem : Cannot find drive. A drive with the name '#{ Join-Path $Config.InstallPath $_ =C' does not exist.
At line:1 char:85
+ ... elect-Object { Join-Path $Config.InstallPath $_ } | Get-ChildItem
+ ~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (#{ Join-Path $C...stallPath $_ =D:String) [Get-ChildItem], DriveNotFoun
dException
+ FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand
How can I convert result of Select-Object to simple array of strings? Or any other approach to make code better?

Answer 1

The results you are getting are because you made a new object with the the literal property Join-Path $Config.InstallPath $_. Instead...
$Config.SubPaths | ForEach-Object { Join-Path $Config.InstallPath $_ } | Get-ChildItem
You are not trying to select a property of a single subpath but generate a string from each of the SubPaths. Using Foreach-object instead to iterate over the collection should get you the results you are looking for.
While you could create custom objects and properties using calculated properties I figure this is not the direction you are going for. But to answer the question in the title you could have done this:
$Config.SubPaths |
Select-Object #{Name="Path";Expression={Join-Path $Config.InstallPath $_}} |
Get-ChildItem
Get-ChildItem should bind to the path property of the new object were are making