Can't obtain Document set author via PowerShell

Question

I try to print Authors of all items of docset list in powershell script:

Clear-Host

$web = Get-SPWeb "http://dogovor.ab.ru"
$list = $web.Lists["Agreements"]

$AllItems = $list.Items
foreach ($t in $AllItems)
{
    if ($t.ContentType.Name -eq "Agreement")
    {
        $t.Properties["Author"] # <- null

        $t
    }
}

but the property "Created By" (internal name "Author") is always null, while I can see it on form.
May be there are a list of properties to retrieve or something else.. Thanks for answers!

Answer 1

Instead of using hard code the name its better to use.

[Microsoft.SharePoint.SPBuiltInFieldId]::Author

Your code could look something like this

$url = "<url>"
$list = "<list title>"
$ctName = "<name contenttype>"
$web = Get-SPWeb $url
$list = $web.Lists[$list]

$list.Items | % {
   $item = $_
   if ($item.ContentType.Name -eq $ctName)
   {
       $item[[Microsoft.SharePoint.SPBuiltInFieldId]::Author]
   }
}

Answer 2

Use $t["Author"] instead of $t.Properties["Author"]