Get-ADUser : Cannot Validate argument 'identity'. The argument is null

Question

I'm working on a script and part of it relies on selecting a AD user from a list box. Problem is that the selected user is coming back 'Null'. Have a look at the code below!

$form                                    = New-Object System.Windows.Forms.Form
$form.Text                               = 'Account Selection'
$form.Size                               = New-Object System.Drawing.Size   (400,250)
$form.StartPosition                      = 'CenterScreen'

$OKButton                                = New-Object System.Windows.Forms.Button
$OKButton.Location                       = New-Object System.Drawing.Point  (110,165)
$OKButton.Size                           = New-Object System.Drawing.Size   (75,23)
$OKButton.Text                           = 'OK'
$OKButton.DialogResult                   = [System.Windows.Forms.DialogResult]::OK
$form.AcceptButton                       = $OKButton
$form.Controls.Add($OKButton)

$CancelButton                            = New-Object System.Windows.Forms.Button
$CancelButton.Location                   = New-Object System.Drawing.Point  (190,165)
$CancelButton.Size                       = New-Object System.Drawing.Size   (75,23)
$CancelButton.Text                       = 'Cancel'
$CancelButton.DialogResult               = [System.Windows.Forms.DialogResult]::Cancel
$form.CancelButton                       = $CancelButton
$form.Controls.Add($CancelButton)

$label                                   = New-Object System.Windows.Forms.Label
$label.Location                          = New-Object System.Drawing.Point  (10,0)
$label.Size                              = New-Object System.Drawing.Size   (280,20)
$label.Text                              = 'Select the user account'
$form.Controls.Add($label)

$listBox                                 = New-Object System.Windows.Forms.ListBox
$listBox.Location                        = New-Object System.Drawing.Point  (10,40)
$listBox.Size                            = New-Object System.Drawing.Size   (363,150)
$listBox.Height                          = 120
$form.Controls.Add($listBox)

$form.Topmost                            = $true

$ADUserGroup = Get-ADObject -Filter 'ObjectClass -eq "User"' -SearchBase 'OU=Users,DC=Company,DC=com' | sort name

foreach ($User in $ADUserGroup)
{
$listBox.Items.Add($User.Name) | Out-Null
}

$result = $form.ShowDialog()

#Store results
if ($result -eq 'Cancel') {exit}
if ($result -eq [System.Windows.Forms.DialogResult]::OK)
{
$Name = $listBox.SelectedItem
$Employee = Get-ADUser -Filter {SamAccountName -eq $Name}
}

Get-ADUser -Identity $Employee

After the user is selected we should be able to run more AD related commands using the $Employee variable. Below is the error.

   Get-ADUser : Cannot validate argument on parameter 'Identity'. The argument is null. Provide a valid value for the argument, and then try running the command again.
    At line:69 char:22
    + Get-ADUser -Identity $Employee
    +                      ~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [Get-ADUser], ParameterBindingValidationException

Answer 1

It must be that your $Employee variable is null when it gets to the Get-ADUser -Identity $Employee call. $Employee comes from the line $Employee = Get-ADUser -Filter {SamAccountName -eq $Name} , so it must be that AD can't find a user with SamAccountName = $Name .

Write some output for the $Employee variable and see if it is indeed null. Then figure out whether the $Name variable is correct and if that person exists in AD.

Answer 2

I would suggest using the listboxes SelectedIndex instead of the SelectedItem property.

Also, instead of using Get-ADObject , why not use Get-ADUser in the first place.

Taken from the part where the form is built, just below $form.Topmost = $true , this should work for you:

# Get an array of all user objects in the given OU and sort by property Name
# By default, these objects will have the following properties:
#   DistinguishedName, Enabled, GivenName, Name, ObjectClass,
#   ObjectGUID, SamAccountName, SID, Surname, UserPrincipalName

# If you need more or other properties, then you need to add the -Properties 
# parameter to the Get-ADUser cmdlet below.
$ADUserGroup = Get-ADUser -SearchBase 'OU=Users,DC=Company,DC=com' | Sort-Object Name

foreach ($User in $ADUserGroup) {
    $listBox.Items.Add($User.Name) | Out-Null
}

$result        = $form.ShowDialog()
$selectedIndex = $listBox.SelectedIndex

# close and remove the form
$form.Dispose()

# handle the results
if ($result -eq [System.Windows.Forms.DialogResult]::OK -and $selectedIndex -ge 0) {
    # store the selected AD user object in variable $Employee and do the rest of your code with it
    $Employee = $ADUserGroup[$selectedIndex]
}

# $Employee now holds the ADUser object with all properties you asked for or is $null if no selection was made