Powershell: Populate a Multi-Value People Picker via CSOM

Question

I'm currently working on a script to update a SharePoint list in a 2013 Dedicated environment.

One of the fields on the list is a Multi-Valued 'People Picker' field and I can't figure out how to properly set its value using Powershell and the Microsoft.SharePoint.Client namespace.

I have a list of Usernames in the format of 'domain\username'. I'm iterating through each and calling SPWeb.EnsureUser to get a Microsoft.SharePoint.Client.User object.

After that, I'm at a loss as to what I should be doing. Below is a example of what I've been trying. The EnsureUser function is just a helper function I wrote that retrieves the Web object from the current Site $context and then call $web.EnsureUser. Once this is done, however, my list item does not contain the user I would expect.

$userName = "whd\wholland"
$spuser = EnsureUser $context $user             
if($spuser -ne $null){
     #Really not sure what to do here.
     $spuserValue = New-Object Microsoft.SharePoint.Client.FieldUserValue
     $spuserValue.LookupId = $spuser.id                 
     $listItem["AllOwners"] = @($spuserValue)
}
$listItem.Update()

Answer 1

Finally found the solution to my problem.

I was trying to set the value of my field to a generic array.

What I needed to do was to create a generic array, add my user value to it and then convert the array to have the appropriate specific type...FieldUserValue in this case.

$userName = "whd\wholland"
$spuser = EnsureUser $context $userName
$lookupValueCollection = @()             
if($spuser -ne $null){         
     $spuserValue = New-Object Microsoft.SharePoint.Client.FieldUserValue
     $spuserValue.LookupId = $spuser.id                 
     $lookupValueCollection += $spuserValue
}
$userValueCollection = [Microsoft.SharePoint.Client.FieldUserValue[]]$lookupValueCollection 
$listItem["AllOwners"] = $userValueCollection
$listItem.Update()