Getting a FieldLookupValue from Sharepoint in Powershell - powershell

Question

Looking on the net I came up with this 2 functions to request Sharepoint using this 3 DLL with powershell :
Microsoft.SharePoint.Client.dll
Microsoft.SharePoint.Client.Taxonomy.dll
Microsoft.SharePoint.Client.Runtime.dll
This function is used to get all items from a list
Function Get-ListItems([Microsoft.SharePoint.Client.ClientContext]$Context, [String]$ListTitle) {
$list = $Context.Web.Lists.GetByTitle($listTitle)
$qry = [Microsoft.SharePoint.Client.CamlQuery]::CreateAllItemsQuery()
$items = $list.GetItems($qry)
$Context.Load($items)
$Context.ExecuteQuery()
return $items
}
And this one to work the list :
Function getChangeListsFromSharepoint(){
$context = New-Object Microsoft.SharePoint.Client.ClientContext($Url)
$items = Get-ListItems -Context $context -ListTitle $listName
foreach($item in $items)
{
/** Working HERE **/
}
$context.Dispose()
}
Now when I'm displaying all item content using Write-Host $item.Fields I've got something like this :
[Title,"blabla"]
...
[SpecialField,Microsoft.SharePoint.Client.FieldLookupValue[]]
[OtherField,Microsoft.SharePoint.Client.FieldLookupValue]
I'm trying to get the value of SpecialField and OtherField. To do so I'm using $item["SpecialField"].LookupValue. And I've got no problem. But when I'm doing it on OtherField the value is empty. If I try to use $item["OtherField"].LookupID the value is not empty and I've got an ID. How can I get the value behind this ID ? What's the difference between FieldLookupValue[] and FieldLookupValue ?

Answer 1

FieldLookupValue[] is a multi-value lookup column.
It has property Allow multiple values set to true and contains an array of items.
So, $item["OtherField"].LookupValue will not work here, you need to iterate it over as below:
#multi-value lookup
$mvLookup = [Microsoft.SharePoint.Client.FieldLookupValue[]] $item["OtherField"]
$mvLookup |% { "Lookup Value: $($_.LookupId):$($_.LookupValue)" }
which results in values as below:
FieldLookupValue is a single value lookup column. It has the Allow multiple values set to false and contains a single item. So, $item["SpecialField"].LookupValue will work here

Answer 2

So the solution was easy : my user didn't had the rights to explore the (field)list because it was from a (sharepoint)list on wich he didn't had any rights. What is strange is that on the website the value was visible but it's not when using powershell.