PowerShell: How to change table headers in loop? - powershell

Question

I want to collect data remotely and adapt the table headers later with the help of an xml-file. This should happen in a loop, looking like that:
foreach($tableheader in $table) {
$table.$tableheader = $xmlFile.$tableheader
}
Amongst others I tried the following:
$x = 0
$sitesonfig = Get-ConfigSite -AdminAddress localhost
foreach($Prop in ($siteconfig |get-member -MemberType Property | select -Property name))
{
$x += 1;
$siteconfig = $siteconfig | Select-Object * | format-table #{l="Smile$x";e={$_.$Prop}}
}
Yes, I know this looks silly, but I've got really no idea, how to change the headers one by one without listing each time all the other headers, too.

Answer 1

One possibility is to use a loop to create the header map that you pass into Format-Table.
Here is your second example modified to demonstrate this concept. You should be able to adapt this to grab the header info from your XML file.
$x = 0
$siteconfig = Get-ConfigSite -AdminAddress localhost
$headerMap = #()
foreach($Prop in ($siteconfig |get-member -MemberType Property | select -ExpandProperty name))
{
$x += 1;
$headerMap += #{
l="Smile$x";
e={ $_.$Prop }.GetNewClosure()
}
}
$siteconfig | Format-Table $headerMap
Important Points
Select -Property name needed to be changed to Select -ExpandProperty name. The reason for this is that Select-Object in PowerShell will return an object filtered down to the selected member but you need a string for grabbing the property value by name. The -ExpandProperty parameter will expand this to be the string value instead.
The expression block needs GetNewClosure() called on it to capture the value of $Prop at the time of script block creation versus at the time of calling. This will probably be a little confusing if you are new to the concept of closures and PowerShell's scoping rules. Without this, due to PowerShell's scoping rules, $Prop will evaluate to the value of $Prop at the time it is used by Format-Table. By calling GetNewClosure(), the value of $Prop is captured when GetNewClosure() is called which is what we want in this case.