Setting the default value for a taxonomy field

Question

I have been creating a load of site columns with powershell from a .csv file. I am now trying to create new taxonomy or metadata field:

               $spField = $web.Fields.CreateNewField($fieldType, $siteColumn.DisplayName)
                    # updat properties related ot MMS
                    # Update the properties of the new field.
                    $spField.SspId = $termSet.TermStore.ID
                    $spField.TermSetId = $termSet.Id 
                    $spField.AnchorId = $termID

but I also want to set a default value (not just the anchor for a range of terms)

  $defaultTerm = $terms | Where-Object {$_.Name -eq $siteColumn.Default}

Now I am stuck because I need update $spField.DefaultValue with a format it accepts e.g.

 45;#Customer Document|60d5d501-3d38-4842-80f0-c897a12b7e34

How can I do this from a .csv file?

Answer 1

For each field you should identify the default term name. Then to get the Unique ID, you need to iterate through the term store as below

$session = New-Object Microsoft.SharePoint.Taxonomy.TaxonomySession($site) 
$termStore = $session.TermStores[0] 
$group = $termStore.Groups["GroupName"] 
$termSet = $group.TermSets["TermsetName"] 
$terms = $termSet.GetAllTerms() 
$term = $terms | ?{$_.Name –eq "TermName"}

Once you have the $term, you can form the default value as

"45;#" + $term.Name + "|" + $term.Id

Answer 2

The "45" in @Amal's example is the SpssId. The SpssId only gets created when a taxonomy term has been used in a list or a library. It is actually the Id of a list item for a given term in the TaxonomyHiddenList.

Rather that use "45" or "-1" you can simply write a once off script to create a list item for every term in the term store. The Taxonomy Update Scheduler timer job will then create items in the TaxonomyHiddenList for each term, the Id of each of these list items is the SpssId accessible in the API TaxonomyField.GetWssIdsOfTerm object/method. This method will fail if the term has never been used before so that is why you need the once of script and a list to populate items with every term thereby using all the terms.

Such is the SP design for this, you cannot get an Spssid for a given term unless it has actually been used in a list or a library and only after the Taxonomy Update Scheduler has created the list items in the TaxonomyHiddenList. I think its an odd design but there may reasons why it works this way...