在Get-AdUser中使用哈希表变量

Question

Consider the following code fragment

$User = @{Username = "fred.bloggs"}
$Username = $User.Username
Get-AdUser -Filter {SamAccountName -eq $Username}               # this works
Get-AdUser -Filter {SamAccountName -eq $User.Username}          # this throws an error

The first Get-User works but the second fails with:

Get-AdUser : Property: 'Username' not found in object of type: 'System.Collections.Hashtable'.

I'm aware of PowerShell's parsing quirks with objects and left-to-right parsing and would normally wrap this in $($User.Username) but that doesn't work either.

I know the answer is simple!

Answer 1

Since -Filter is looking for a System.String , you can get around the parsing issue by using double quotes instead of a script block:

Get-ADUser -Filter "SamAccountName -eq '$($User.Username)'"

Get-ADUser will convert any script block passed to -Filter to a string for evaluation, so it can be helpful to use a string in the first place.

Answer 2

Sadly i cannot tell you why it fails but this could be a workaround for you:

$filter = [scriptblock]::create("SamAccountName -eq $($User.Username)")
Get-AdUser -filter $filter

If you find out the reason for the behaviour you experienced i would be happy to hear about it :)

Regards

Update:

The probable reason this happens is because -Filter expects a String, if given the expression inside of {} it will interpret it as Advanced Filter, which do not support function invocation and stuff like this. Source: MSDN (Thanks Kohlbrr)