How to update SharePoint enterprise keywords with multiple values using powershell? - sharepoint

Question

I'm trying to write a powershell script that looks at a user defined variable and updates the enterprise keywords for each item in a list that matches that value.
For instance, say you have a page in SP that has the managed metadata keywords: new, fresh, clean
I want a script that asks a user what keyword they want to swap out. So a user would specify a variable as: fresh and another variable as: fresher and it would update any item with the keyword fresh to fresher.
Here's what I 've used before but doesn't work now because there are mutliple values:
Add-PSSnapin Microsoft.SharePoint.PowerShell -EA SilentlyContinue
$webURL = <MY SP URL>
$listName = <MY LIST NAME>
$web = Get-SPWeb $webURL
$list = $web.Lists[$listName]
$listitems = $list.items
$session = Get-SPTaxonomySession -Site $web.Site
$termStore = $session.TermStores["Managed Metadata Service"]
$group = $termStore.Groups["Resources"]
$termset = $group.TermSets["Wiki Categories"]
$terms = $termSet.GetTerms(100)
$wiki1 = read-host "Enter the wiki category you want to update"
$wiki2 = read-host "Enter the replacement wiki category"
$term = $terms | ?{$_.name -eq $wiki2}
Foreach($item in $listitems)
{$wiki = $item["Wiki Categories"]
if($wiki.label -eq $term)
{
$spitem = [Microsoft.SharePoint.SPListItem]$item;
$taxfield = [Microsoft.SharePoint.Taxonomy.TaxonomyField]$spitem.Fields["Wiki Categories"]
$taxfield.SetFieldValue($spitem, $term)
$spitem.Update()
$spitem.File.Publish("True")
}
}
I'm pretty sure the issue is with this line:
$term = $terms | ?{$_.name -eq $wiki2}
And this line:
$taxfield.SetFieldValue($spitem, $term)

Answer 1

The problem is that you passing a TermCollection ($term) to SetFieldValue where you should pass in a TaxonomyFieldValueCollection.
You can convert them like this:
$taxfield = $spitem.Fields["Wiki Categories"]
$tfvc = new-object -typename Microsoft.SharePoint.Taxonomy.TaxonomyFieldValueCollection -argumentlist $taxfield;
foreach($t in $ term)
{
$tfv = new-object -typename Microsoft.SharePoint.Taxonomy.TaxonomyFieldValue -argumentlist $taxfield
$tfv.TermGuid = $t.Id
$tfv.Label = $t.Name
$tfvc.Add($tfv)
}
...
$taxfield.SetFieldValue($spitem, $tfvc)